This is not extensive list of references, but rather articles that we are aware of and we think are relevant.

Anyone that wants to contribute their own citation or would like to recommend a citation should please contact info@has-motion.ca.

Scherpereel, K., Molinaro, D., Inan, O. et al. (2023) A human lower-limb biomechanics and wearable sensors dataset during cyclic and non-cyclic activities Scientific Data 10, article number 924 DOI Tasks of daily living are often sporadic, highly variable, and asymmetric. Analyzing these real-world non-cyclic activities is integral for expanding the applicability of exoskeletons, protheses, wearable sensing, and activity classification to real life, and could provide new insights into human biomechanics. Yet, currently available biomechanics datasets focus on either highly consistent, continuous, and symmetric activities, such as walking and running, or only a single specific non-cyclic task. To capture a more holistic picture of lower limb movements in everyday life, we collected data from 12 participants performing 20 non-cyclic activities (e.g. sit-to-stand, jumping, squatting, lunging, cutting) as well as 11 cyclic activities (e.g. walking, running) while kinematics (motion capture and IMUs), kinetics (force plates), and electromyography (EMG) were collected. This dataset provides normative biomechanics for a highly diverse range of activities and common tasks from a consistent set of participants and sensors.

van der Zee TJ, Mundinger EM and Kuo AR (2022) A biomechanics dataset of healthy human walking at various speeds, step lengths and step widths Scientific Data 9, article number 704 DOI The biomechanics of human walking are well documented for standard conditions such as for self-selected step length and preferred speed. However, humans can and do walk with a variety of other step lengths and speeds during daily living. The variation of biomechanics across gait conditions may be important for describing and determining the mechanics of locomotion. To address this, we present an open biomechanics dataset of steady walking at a broad range of conditions, including 33 experimentally-controlled combinations of speed (0.7–2.0 m·s⁻¹), step length (0.5–1.1 m), and step width (0–0.4 m). The dataset contains ground reaction forces and motions from healthy young adults (N = 10), collected using split-belt instrumented treadmill and motion capture systems respectively. Most trials also include pre-computed inverse dynamics, including 3D joint positions, angles, torques and powers, as well as intersegmental forces. Apart from raw data, we also provide five strides of good quality data without artifacts for each trial, and sample software for visualization and analysis.

Fukuchi CA, Fukuchi RK and Duarte M (2018) A public dataset of overground and treadmill walking kinematics and kinetics in healthy individuals Peer J. 2018 DOI In a typical clinical gait analysis, the gait patterns of pathological individuals are commonly compared with the typically faster, comfortable pace of healthy subjects. However, due to potential bias related to gait speed, this comparison may not be valid. Publicly available gait datasets have failed to address this issue. Therefore, the goal of this study was to present a publicly available dataset of 42 healthy volunteers (24 young adults and 18 older adults) who walked both overground and on a treadmill at a range of gait speeds. Their lower-extremity and pelvis kinematics were measured using a threedimensional (3D) motion-capture system. The external forces during both overground and treadmill walking were collected using force plates and an instrumented treadmill, respectively. The results include both raw and processed kinematic and kinetic data in different file formats: c3d and ASCII files. In addition, a metadata file is provided that contain demographic and anthropometric data and data related to each file in the dataset. All data are available at Figshare (DOI: 10.6084/m9.figshare.5722711). We foresee several applications of this public dataset, including to examine the influences of speed, age, and environment (overground vs. treadmill) on gait biomechanics, to meet educational needs, and, with the inclusion of additional participants, to use as a normative dataset.

Dos Santos DA, Fukuchi CA, Fukuchi RK, Duarte M. (2017) A data set with kinematic and ground reaction forces of human balance. PeerJ. 2017 Jul 27;5:e3626. PMID: 28761798 This article describes a public data set containing the three-dimensional kinematics of the whole human body and the ground reaction forces (with a dual force platform setup) of subjects who were standing still for 60 s in different conditions, in which the subjects' vision and the standing surface were manipulated. Twenty-seven young subjects and 22 old subjects were evaluated. The data set comprises a file with metadata plus 1,813 files with the ground reaction force (GRF) and kinematics data for the 49 subjects (three files for each of the 12 trials plus one file for each subject). The file with metadata has information about each subject's sociocultural, demographic, and health characteristics. The files with the GRF have the data from each force platform and from the resultant GRF (including the center of pressure data). The files with the kinematics contain the three-dimensional positions of 42 markers that were placed on each subject's body and 73 calculated joint angles. In this text, we illustrate how to access, analyze, and visualize the data set. All the data is available at Figshare (DOI: 10.6084/m9.figshare.4525082), and a companion Jupyter Notebook presents programming code to access the data set, generate analyses and other examples. The availability of a public data set on the Internet that contains these measurements and information about how to access and process this data can potentially boost the research on human postural control, increase the reproducibility of studies, and be used for training and education, among other applications.

Fukuchi RK, Fukuchi CA, Duarte M (2017) A public dataset of running biomechanics and the effects of running speed on lower extremity kinematics and kinetics. PeerJ. 2017 May 9;5:e3298. PMID: 28503379 BACKGROUND The goals of this study were (1) to present the set of data evaluating running biomechanics (kinematics and kinetics), including data on running habits, demographics, and levels of muscle strength and flexibility made available at Figshare (DOI: 10.6084/m9.figshare.4543435); and (2) to examine the effect of running speed on selected gait-biomechanics variables related to both running injuries and running economy. METHODS The lower-extremity kinematics and kinetics data of 28 regular runners were collected using a three-dimensional (3D) motion-capture system and an instrumented treadmill while the subjects ran at 2.5 m/s, 3.5 m/s, and 4.5 m/s wearing standard neutral shoes. RESULTS A dataset comprising raw and processed kinematics and kinetics signals pertaining to this experiment is available in various file formats. In addition, a file of metadata, including demographics, running characteristics, foot-strike patterns, and muscle strength and flexibility measurements is provided. Overall, there was an effect of running speed on most of the gait-biomechanics variables selected for this study. However, the foot-strike patterns were not affected by running speed. DISCUSSION Several applications of this dataset can be anticipated, including testing new methods of data reduction and variable selection; for educational purposes; and answering specific research questions. This last application was exemplified in the study's second objective.

Back to Top

Pieter Meyns has made a gait markerset available for children with cerebral palsy (hemiplegia n=5, 9.00 ± 2.28; diplegia n=4, age 10.50 ±1.66) and typically developing children (n=5, age 8.40 ± 1.50). You can access the data at https://simtk.org/projects/cp-child-gait/. SimTK has a number of other datasets available, which you might search to see if there are other ones that meet your needs.

SimTK

Back to Top

Kaufman K, Miller E, Kingsbury T, Russell Esposito E, Wolf E, Wilken J, Wyatt M. (2016) Reliability of 3D gait data across multiple laboratories 2016 - Jul 25;49:375-38. PMID: 27497755 The aim of this study was to analyze the repeatability of gait analysis studies performed across multiple trials, sessions, and laboratories. Ten healthy participants (6 male/4 female, mean age of 30, mean BMI of 24kg/m2) were assessed in 3 sessions conducted at each of the three Centers of Excellence for Amputee Care within the Department of Defense. For each test session, kinematic and kinetic parameters were collected during five walking trials for each limb. One independent examiner at each site placed markers on the subjects. Biomechanical data were collected at two walking speeds: self-selected and Froude speed. Variability of the gait data was attributed to inter-trial, inter-session, and inter-lab errors for each subject. These error sources were averaged across all ten subjects to obtain a pooled error estimate. The kinematic errors were fairly consistent at the two walking speeds tested. Median inter-lab kinematic errors were <5.0° (median 2.3°) for all joint angle measurements. However, the kinetic error differed significantly between walking speeds. The median inter-lab kinetic error for the self-selected speed was 0.112Nm/kg (ICR 0.091-0.184) with a maximum of 0.226Nm/kg. The errors were greatly reduced when the subjects walked at their Froude speed. The median inter-lab error was 0.048Nm/kg (ICR 0.025-0.078, maximum 0.086). These data demonstrate that it is possible to get reliable data across multiple gait laboratories, particularly when gait speed is standardized across testing sessions. A key similarity between sites was the use of identical anatomical segment definitions for the respective gait models.

Miller E, Kaufman K, Kingsbury T, Wilken J, Wyatt M. (2016) Mechanical testing for three-dimensional motion analysis reliability. 2016 - Gait & Posture. 2016 Oct;50:116-119. PMID: 27592076 The purpose of this study was to use simple mechanical tests to evaluate the reliability of three-dimensional motion analysis systems and biomechanical models. Three different tests were conducted at four motion analysis laboratories where clinical care and research studies are routinely performed. The laboratories had different motion capture systems, different types and number of cameras, different types and numbers of force plates and different biomechanical models. These mechanical tests evaluated the accuracy of the motion capture system, the integration of the force plate and the motion capture system, and the strength of the biomechanical model used to calculate rotational kinematics. Results of motion capture system accuracy tests showed that, for all labs, the error between the measured and calculated distances between markers was less than 2mm and 1° for marker separations which ranged from 24mm to 500mm. Results from the force plate integration tests demonstrated errors in center of pressure calculation of less than 4mm across all labs, despite varied force plate and motion system configurations. Finally, errors across labs for single joint rotations and for combined rotations at the hip and knee were less than 2° at the hip and less than 10° at the knee. These results demonstrate that system accuracy and reliability can be obtained allowing the collection of comparable data across different motion analysis laboratories with varying configurations and equipment. This testing is particularly important when multi-center studies are planned in order to assure data consistency across labs.

Hutchinson L, Schwartz JB, Morton AM, Davis IS, Deluzio KJ, Rainbow MJ (2018) Operator Bias Errors Are Reduced Using Standing Marker Alignment Device for Repeated Visit Studies 2018 - J Biomech Eng 140 When optical motion capture is used for motion analysis, reflective markers or a digitizer are typically used to record the location of anatomical landmarks identified through palpation. The landmarks are then used to construct anatomical coordinate systems. Failure to consistently identify landmarks through palpation over repeat tests creates artifacts in the kinematic waveforms. The purpose of this work was to improve intra- and inter-rater reliability in determining lower limb anatomical landmarks and the associated anatomical coordinate systems using a marker alignment device (MAD). The device aids the subject in recreating the same standing posture over multiple tests, and recreates the anatomical landmarks from previous static calibration trials. We tested three different raters who identified landmarks on eleven subjects. The subjects performed walking trials and their gait kinematics were analyzed with and without the device. Ankle kinematics were not improved by the device suggesting manual palpation over repeat visits is just as effective as the MAD. Intra-class correlation coefficients between gait kinematics registered to the reference static trial and registered to follow-up static trials with and without the device were improved between 1% and 33% when the device was used. Importantly, out-of-plane hip and knee kinematics showed the greatest improvements in repeatability. These results suggest that the device is well suited to reducing palpation artifact during repeat visits to the gait lab.

Noehren B1, Manal K, Davis I. (2010) Improving between-day kinematic reliability using a marker placement device. J Orthop Res. 2010 Nov;28(11):1405-10. PMID: 20872574 3D motion analysis is commonly used to measure clinical outcomes, involving repeated measures over time. However, the day-to-day reliability of these measurements has been questioned and few attempts have been made to improve this reliability. Our purpose was to determine if a marker placement device (MPD) could improve day-to-day kinematic reliability as compared to manual marker placement. Ten healthy runners participated. Day-to-day comparisons of peak angles were made between manual marker placement and the use of an MPD. Reliability of each method was determined with intraclass correlation coefficients (ICC) and standard errors of measurement (SEM). The ICC and SEM values improved with the MPD. With the MPD, 7 out of 9 ICC values were >0.9 compared to only 3 when using manual marker placement. Additionally, the largest reduction in SEM values was in the transverse plane. Use of the MPD increases the power to detect smaller differences in studies of where gait is assessed over time.

Jason M. Wilken, Kelly M. Rodriguez, Melissa Brawner, Benjamin J. Darter. (2011) Reliability and minimal detectible change values for gait kinematics and kinetics in healthy adults. 2009 - Gait & Posture. 2011. Epub 2011 Oct 29. The purpose of the current study is to determine the intra-rater and inter-rater reliability and MDC for commonly used gait variables within a single session and between sessions. A second objective is to examine the effect of walking velocity on reliability and MDC variables. The results of the current study suggest that reliability is good to excellent across a range of controlled walking velocities and the introduction of a second rater does not appreciably impact ICC or MDC values. In young healthy adults changes in gait kinematics of greater than approximately 5 degrees can be identified when comparing between sessions.

Ford F, Myer GD, Hewett TE (2007) Reliability of Landing 3D Motion Analysis: Implications for Longitudinal Analyses. Medicine & Science in Sports & Exercise. 39(11):2021-2028 PURPOSE: Biomechanical measures quantified during dynamic tasks with coupled epidemiological data in longitudinal experimental designs may be useful to determine which mechanisms underlie injury risk in young athletes. A key component is the ability to reliably measure biomechanical variables between testing sessions. The purpose was to determine the reliability of three-dimensional (3D) lower-extremity kinematic and kinetic variables during landing in young athletes measured within a session and between two sessions 7 wk apart. METHODS: Lower-extremity kinetics and kinematics were quantified during a drop vertical jump. Coefficient of multiple correlations (CMC), intraclass correlation coefficients (ICC (3, k), ICC (3, 1)), and typical error (TE) analyses were used to examine within- and between-session reliability. RESULTS: There were no differences in within-session reliability for peak angular rotations between planes with all discrete variables combined (sagittal ICC > or = 0.933, frontal ICC > or = 0.955, transverse ICC > or = 0.934). Similarly, the between-session reliability of kinematic measures were not different between the three planes of motion but were lower than the within-session ICC. The within- and between-session reliability of discrete joint moment variables were excellent for all sagittal (within ICC > or = 0.925, between ICC > or = 0.800) and frontal plane moment measures (within ICC > or = 0.778, between ICC > or = 0.748). CMC analysis revealed similar averaged within-session (CMC = 0.830 +/- 0.119) and between-session (CMC = 0.823 +/- 0.124) waveform comparisons. CONCLUSION: The majority of the kinematic and kinetic variables in young athletes during landing have excellent to good reliability. The ability to reliably quantify lower-extremity biomechanical variables of young athletes during dynamic tasks over extended intervals may aid in identifying potential mechanisms related to injury risk factors.
Back to Top

Holden JP, Selbie WS, Stanhope SJ (2003) A proposed test to support the clinical movement analysis laboratory Gait and Posture 17, 2003, 205-213. CalTesterReference This paper describes a testing methodology and resultant set of four variables that can be used to quickly and easily document the correct installation, configuration, and combined working status of force platform (FP) and three-dimensional (3D) motion capture components of a clinical movement analysis (CMA) laboratory. Using a rigid, rod-shaped testing device, CMA laboratory data are collected simultaneously from the FP and motion capture components (typically, video-based kinematic measurements) as the device is manually loaded while being pivoted broadly about a point on the FP. Using a computational method based on static equilibrium, it is possible to independently measure the rod's orientation and tip position during the moving trial, using FP derived data exclusively, and to compare these estimates to rod orientation and tip position estimates derived exclusively from the motion capture component. The motion laboratory accreditation test (MLAT) variables include: the difference (angle) between the orientation of the long axis of the testing device as independently determined from kinematic measures (motion capture component) and the FP derived data; and the difference (x, y, z) between the center of pressure position (FP derived) and the position of the testing device tip (motion capture derived) that loads the FP. A numerical dynamics model was explored to evaluate the appropriateness of the static equilibrium-based FP data model and to determine guidelines for testing device movement frequency and FP loading. The MLAT technique provides a simple means of detecting the combined presence of errors from many sources, several of which are explored in this paper. The MLAT has been developed to help meet one criteria of the CMA laboratory accreditation process, and to serve as a routine quality assessment tool.

Goldberg SR, Kepple TM, Stanhope SJ (2009) In Situ Calibration and Motion Capture Transformation Optimization Improve Instrumented Treadmill Measurements“ Journal of Applied Biomechanics, 2009, 25, 401-406 FPLoc Reference We increased the accuracy of an instrumented treadmill’s measurement of center of pressure and force data by calibrating in situ and optimizing the transformation between the motion capture and treadmill force plate coordinate systems. We calibrated the device in situ by applying known vertical and shear loads at known locations across the tread surface and calculating a 6 × 6 calibration matrix for the 6 output forces and moments. To optimize the transformation, we first estimated the transformation based on a locating jig and then measured center-of-pressure error across the treadmill force plate using the CalTester tool. We input these data into an optimization scheme to find the transformation between the motion capture and treadmill force plate coordinate systems that minimized the error in the center-of-pressure measurements derived from force plate and motion capture sources. When the calibration and transformation optimizations were made, the average measured error in the center of pressure was reduced to approximately 1 mm when the treadmill was stationary and to less than 3 mm when moving. Using bilateral gait data, we show the importance of calibrating these devices in situ and performing transformation optimizations.
Back to Top

Robertson G., Caldwell G., Hamill J., Kamen G.,Whittlesey S. (2004) Research Methods in Biomechanics 2004 - Human Kinetics This text provides a firm foundation in the biomechanical methods and tools necessary for quantifying human movements. Research Methods in Biomechanics is an invaluable resource for developing and seasoned researchers wishing to hone their skills and learn new techniques in the collection, analysis, and interpretation of data. The reference shows how the laws of motion are applied to complex human movements. The text demonstrates how to combine segments to obtain limb or total-body measures. All the material is presented in such a way that you need only basic knowledge of Newtonian mechanics and vector algebra to benefit.

Chapman AE Biomechanical Analysis of Fundamental Human Movements 2008 - Human Kinetics Unlike previous biomechanics texts that have taken a mechanical concept and identified activities in which the concept is implicated, Biomechanical Analysis of Fundamental Human Movements takes a contrary approach by focusing on the activities and then identifying the biomechanical concepts that best facilitate understanding of those activities. Superbly illustrated with more than 140 figures depicting the critical points of biomechanical analysis, this two-color text is an invaluable tool for those pursuing the study of advanced quantitative biomechanics. It presents a clear introduction to the principles that underlie all human motion and provides a complete study of fundamental human movements and their components.

Richards J Biomechanics in Clinics and Research: An interactive teaching and learning course 2008 - Elsevier This title is directed primarily towards health care professionals outside of the United States. It is a unique resource, which combines an exceptional online course with a practical and accessible book. The course is thoroughly integrated with the text and the many high-quality animations, interactive tests and clear explanations will enable you to gain a confident understanding of the clinical aspects of biomechanics.

Richards J The Comprehensive Textbook of Clinical Biomechanics, 2nd Edition 2018 - Elsevier ALL-ENCOMPASSING and EXPANDED, now covering the WHOLE BODY (lower quadrant PLUS upper quadrant and spine) - The Comprehensive Textbook of Clinical Biomechanics (formerly Biomechanics in Clinic and Research) presents the latest research in a form which is accessible, practical, thorough and up-to-the minute. Written by a leading expert in the field, The Comprehensive Textbook of Clinical Biomechanics will enable you to gain a confident understanding of the clinical aspects of biomechanics.

Helliwell, Woodburn, Redmond, Turner, Davys (2008) Reference The Foot and Ankle in Rheumatoid Arthritis 2008 - Elsevier Comprehensive and accessible, this unique book emphasizes a practical and evidence-based approach to the foot and ankle in rheumatoid arthritis. Information is concise, up to date, and well illustrated. The team of authors consists of rheumatologists and podiatrists based at the highly respected Foot and Ankle Studies in Rheumatology (FASTER) programme, with contributors including both surgeons and orthotists. A companion DVD contains many video clips of examination and injection techniques and gait analyses, additional downloadable images, assessment tools and an interactive injection resource.

Hamill J, Knutzen K (2003) Reference Biomechanical Basis of Human Movement 2003 - Lippincott Williams & Wilkins; 2 edition This introductory text in biomechanics integrates basic anatomy, physics, calculus, and physiology for the study of human movement. Organized into three parts (Foundations of Human Movement, Functional Anatomy, and Mechanical Analysis of Human Movement), this text is considered to be a \”higher\“ level biomechanics book as it can be used in both upper level undergraduate and graduate courses. NEW TO THIS EDITION: New coverage of physical activity and bone formation, osteoarthritis, osteoporosis, factors influencing force and velocity development in the muscle, and the effect of training on muscle activation New and updated illustrations include applications from ergonomics, orthopedics, and exercise (supplemented with references from the current biomechanics literature)
Back to Top

French MA, Koller C, Arch ES (2019) Comparison of three kinematic gait event detection methods during overground and treadmill walking for individuals post stroke Journal of Biomechanics, in press Detecting gait events using ground reaction forces (i.e. kinetic detection) is the gold standard, but it is not always possible. Kinematic methods exist; however, accuracy of these methods in stroke survivors during treadmill and overground walking is unknown. Thus, this study compared the accuracy of three kine- matic methods during overground and treadmill walking in stroke survivors. Heel strike and toe off were calculated bilaterally using three kinematic methods (horizontal sacral-heel distance, horizontal ankle- heel distance, and horizontal velocity) and a kinetic method for ten stroke survivors. We calculated true and absolute error for each kinematic method relative to the kinetic method to evaluate accuracy. Repeated-measures ANOVAs compared the absolute error between the different methods for each condi- tion. There was a significant effect of method for all conditions except heel strike during treadmill walk- ing. Post hoc tests showed ankle-heel distance detected heel strike with significantly less error than the other methods during overground walking (p < 0.05). Ankle-heel distance identified 93.0% and 77.8% of gait events within 50 ms of the kinetic event for overground and treadmill walking, respectively. Sacral-heel distance detected toe-off with significantly less error than the other methods during over- ground and treadmill walking (p < 0.05) and identified 87.2% and 90.3% of gait events within 50 ms of the kinetic event for overground and treadmill walking, respectively. Results suggest that ankle-heel dis- tance and sacral-heel distance accurately detect heel strike and toe-off, respectively, in stroke survivors.

Stanhope SJ, Kepple TM, McGuire DA, Roman NL (1990) A Kinematic-Based Technique for Event Time Determination During Gait Medical and Biological Engineering and Computing 28:355-360 A kinematic-based technique for the estimation of the times at which gait events occur is presented. A kinematic-based model (KM) is defined by the trajectory of a point, which has an anatomically fixed location on the subject's body, about a time at which a measurement system defined gait event takes place. The times at which subsequent occurrences of the gait event takes place are determined by identifying the kinematic pattern that best fits the previously defined KM. The results of an experiment that used the gait patterns of a normal and a pathological walker indicate that the accuracy of the algorithm is limited by the kinematic data sampling interval and that optimal kinematic predictors of gait event times occur within the primary (sagittal) plane of motion. The technique is intended to obviate the need for multiple force plates, instrumented floors and instruments which are worn by the subject for the purpose of determining the times at which gait events occur.

Zeni JA Jr, Richards JG, Higginson JS. (2007) Two simple methods for determining gait events during treadmill and overground walking using kinematic data. Gait & Posture. 2008 May;27(4):710-4. The determination of gait events such as heel strike and toe-off provide the basis for defining stance and swing phases of gait cycles. Two algorithms for determining event times for treadmill and overground walking based solely on kinematic data are presented. Kinematic data from treadmill walking trials lasting 20-45s were collected from three subject populations (healthy young, n=7; multiple sclerosis, n=7; stroke, n=4). Overground walking trials consisted of approximately eight successful passes over two force plates for a healthy subject population (n=5). Time of heel strike and toe-off were determined using the two new computational techniques and compared to events detected using vertical ground reaction force (GRF) as a gold standard. The two algorithms determined 94% of the treadmill events from healthy subjects within one frame (0.0167s) of the GRF events. In the impaired populations, 89% of treadmill events were within two frames (0.0334s) of the GRF events. For overground trials, 98% of events were within two frames. Automatic event detection from the two kinematic-based algorithms will aid researchers by accurately determining gait events during the analysis of treadmill and overground walking.

Smith L, Preece S, Mason D, Bramah C. (2015) A comparison of kinematic algorithms to estimate gait events during overground running. Gait & Posture. 2015 Jan;41(1):39-43. The gait cycle is frequently divided into two distinct phases, stance and swing, which can be accurately determined from ground reaction force data. In the absence of such data, kinematic algorithms can be used to estimate footstrike and toe-off. The performance of previously published algorithms is not consistent between studies. Furthermore, previous algorithms have not been tested at higher running speeds nor used to estimate ground contact times. Therefore the purpose of this study was to both develop a new, custom-designed, event detection algorithm and compare its performance with four previously tested algorithms at higher running speeds. Kinematic and force data were collected on twenty runners during overground running at 5.6m/s. The five algorithms were then implemented and estimated times for footstrike, toe-off and contact time were compared to ground reaction force data. There were large differences in the performance of each algorithm. The custom-designed algorithm provided the most accurate estimation of footstrike (True Error 1.2 ± 17.1 ms) and contact time (True Error 3.5 ± 18.2 ms). Compared to the other tested algorithms, the custom-designed algorithm provided an accurate estimation of footstrike and toe-off across different footstrike patterns. The custom-designed algorithm provides a simple but effective method to accurately estimate footstrike, toe-off and contact time from kinematic data.

De Asha AR, Robinson MA, Barton GJ (2012) A marker based kinematic method of identifying initial contact during gait suitable for use in real-time visual feedback applications. Gait and Posture. 36(3):650-2 A gait cycle is typically defined as being from heel strike or initial contact (IC) to the next ipsilateral IC using kinetic data. When these data are not available other methods of event definition are required. An algorithm based upon sagittal plane kinematics of the hip, which defines IC at contralateral peak hip extension (PHE) is presented. Kinematic and kinetic data were recorded while 10 unimpaired participants each completed a minimum of 25 overground gait cycles. The accuracy of 551 IC events was evaluated by comparing the agreement of PHE to other kinematic and kinetic algorithms. The mean temporal difference in IC between the PHE algorithm and a kinetic algorithm was +0.0006 � 0.008 s. The 95% Limits of Agreement was �0.018 s. This new PHE algorithm provides simple to implement and accurate gait events for use when kinetic data are not available.

Handsaker JC, Forrester SE, Folland JP, Black MI, Allen SJ. (2016) A kinematic algorithm to identify gait events during running at different speeds and with different footstrike types. J Biomech. 2016 Dec 8;49(16):4128-4133. Although a number of algorithms exist for estimating ground contact events (GCEs) from kinematic data during running, they are typically only applicable to heelstrike running, or have only been evaluated at a single running speed. The purpose of this study was to investigate the accuracy of four kinematics-based algorithms to estimate GCEs over a range of running speeds and footstrike types. Subjects ran over a force platform at a range of speeds; kinetic and kinematic data was captured at 1000Hz, and kinematic data was downsampled to 250Hz. A windowing process initially identified reduced time windows containing touchdown and toe-off. Algorithms based on acceleration and jerk signals of the foot markers were used to estimate touchdown (2 algorithms), toe-off (2 algorithms), and ground contact time (GCT) (4 algorithms), and compared to synchronous 'gold standard' force platform data. An algorithm utilising the vertical acceleration peak of either the heel or first metatarsal marker (whichever appeared first) for touchdown, and the vertical jerk peak of the hallux marker for toe-off, resulted in the lowest offsets (+3.1ms, 95% Confidence Interval (CI): -11.8 to +18.1ms; and +2.1ms, CI: -8.1 to +12.2ms respectively). This method also resulted in the smallest offset in GCT (-1.1ms, CI: -18.6 to +16.4ms). Offsets in GCE and GCT estimates from all algorithms were typically negatively correlated to running speed, with offsets decreasing as speed increased. Assessing GCEs and GCT using this method may be useful when a force platform is unavailable or impractical. Back to Top

Lythgo N, Wilson C, Galea M (2009) Basic gait and symmetry measures for primary school-aged children and young adults whilst walking barefoot and with shoes Gait and Posture 30, 2009, 502-506 This study investigated the basic spatio-temporal gaitmeasures of 898 primary school-aged children (5–13 years) and 82 young adults (18–27 years). Participants completed 6–8 walks at preferred speed alonga GAITRite walkway whilst barefoot and whilst wearing athletic shoes or runners. Outcome measures (non-normalized and normalized) were gait speed, cadence, step and stride length, support base, single and double support, stance duration, foot angle and associated symmetry measures. Non-normalized measures of speed, step and stride length, support base and foot angle increased with age whereas cadence reduced. Normalized measures remained unchanged with age in children whereas the young adults (both conditions) exhibited a 2.3% reduction in single support, a 5.1% increase in double support and a 2.6% increase in stance duration (p < 0.0001). For the entire sample, shoes increased walking speed by 8 cm/s, step length by 5.5 cm, stride length by 11.1 cm and base of support by 0.5 cm. In contrast, foot angle and cadence reduced by 0.18 and 3.9 steps/min respectively. Shoes increased both double support (1.6%) and stance time (0.8%), whereas single support reduced by 0.8%. Symmetry remained unaffected by age. On average, measures of step and stride symmetry (combining both conditions) fell around 0.7 cm, whereas measures of symmetry for step and stance time, single and double support fell around 0.6%. Footwear significantly affected gait (p < 0.0001). Gait may not be mature by age 13. Gait is symmetrical in healthy children and young adults but may change with pathology.

Lythgo N, Wilson C, Galea M (2011) Basic gait and symmetry measures for primary school-aged children and young adults. II: Walking at slow, free and fast speed Gait and Posture 33, 2011, 29-35 This study recorded basic gait data from 656 healthy primary school-aged children (5–13 years) and 81 young adults (18–27 years) whilst walking over-ground across a level walkway at varying speed. It investigated the effect of gait speed and re-examined the issue of gait maturation. Participants completed 6–8 walks at self-selected slow, free and fast speed along a GAITRite walkway whilst wearing athletic shoes. Outcome measures (non-normalized and normalized) were gait speed, cadence, step and stride length, step and stride time, support base, single and double support (%), stance duration (%), foot angle and associated symmetry measures. Compared to free speed, participants walked 24% slower for the slow speed and 30% faster for the fast speed (p < 0.0001). Both normalized and non-normalized measures of cadence, step and stride length increased with speed (p < 0.001) whereas step and stride time reduced (p < 0.001). As a percentage of the gait cycle, single support and stance duration increased with speed (p < 0.001) whereas double support reduced (p < 0.001). Foot angle was significantly less (less toe-out) for the fast speed than the free and slow speeds (p < 0.001) whereas support base was unaffected by speed. Symmetry measures were unaffected by age or speed. Step and stride symmetry differentials (combining conditions) fell around 0.8 cm, whereas symmetry differentials for step and stance time, single and double support fell around 0.7%. This information can be used by clinicians and researchers to assess the gait of children. Back to Top

Serge van Sint Jan (2007) Color Atlas of Skeletal Landmark Definitions: Guidelines for Reproducible Manual and Virtual Palpations 2007 - Churchill Livingstone This book covers most skeletal landmarks that are palpable through manual palpation and virtual palpation (i.e., using 3D models generated from medical imaging). Each chapter focuses on a particular bone or segment and includes: a general anatomical presentation of the bone SL (using images showing real specimens and 3D bone models); very detailed descriptions of skeletal landmarks using manual palpation and virtual palpation. These definitions have been written in order to be reproducible. Each section includes detailed descriptions of all palpable skeletal landmarks for the current bone. Each landmark is described on one page. Also each landmark page is labelled by a unique acronym. The latter should be used for further data exchange and programming in order to guarantee that no redundant label exists.Full colour, over 500 full colour images. Each bone is described in a separate section, making referencing easy Multidisciplinary approach

Ferber R, McLay Davis I, Williams DS, Laughton C. (2002) A comparison of within- and between-day reliability of discrete 3D lower extremity variables in runners. Journal of Orthopedic Research 20: 1139-1145 It is important to understand the day-to-day variability that is attributed to repositioning of markers especially when assessing a treatment effect or response over time. While previous studies have reported reliability of waveform patterns, none have assessed the repeatability of discrete points such as peak angles, velocities and angular excursions which are often used when making statistical and clinical comparisons. The purpose of this study was to compare the within- and between-day variability of discrete kinematic, kinetic, and ground reaction force (GRF) data collected during running. Comparisons for 20 recreational runners were evaluated for within- and between-day reliability of discrete 3D kinematic, kinetic, and GRF variables. The results indicated that within-day comparisons were more reliable than between-day. Joint angular velocity and angular excursion values were more reliable between-days as compared to absolute peak angle measures and may be more useful in interpreting changes in treatment over time. Between-day kinematic and kinetic sagittal plane values were more reliable than secondary plane values. Reliability of GRF data was greater than kinematic and kinetic data for between-day comparisons.

Ferrari A, Benedetti MG, Pavan E, Frigo C, Bettinelli D, Rabuffetti M, Crenna P, Leardini A.(2008) Quantitative comparison of five current protocols in gait analysis. Gait & Posture. 2008 Aug;28(2):207-16 Data collection and reduction procedures, coherently structured in protocols, are necessary in gait analysis to make kinematic and kinetic measurements clinically comprehensible. The current protocols differ considerably for the marker-set and for the biomechanical model implemented. Nevertheless, conventional gait variables are compared without full awareness of these differences. A comparison was made of five worldwide representative protocols by analysing kinematics and kinetics of the trunk, pelvis and lower limbs exactly over the same gait cycles. A single comprehensive arrangement of markers was defined by merging the corresponding five marker-sets. This resulted in 60 markers to be positioned either on the skin or on wands, and in 16 anatomical landmark calibrations to be performed with an instrumented pointer. Two healthy subjects and one patient who had a special two degrees of freedom knee prosthesis implanted were analysed. Data from up-right posture and at least three gait repetitions were collected. Five corresponding experts participated in the data collection and analysed independently the data according to their own procedures. All five protocols showed good intra-protocol repeatability. Joint flexion/extension showed good correlations and a small bias among protocols. Out-of-sagittal plane rotations revealed worse correlations, and in particular knee abduction/adduction had opposite trends. Joint moments compared well, despite the very different methods implemented. The abduction/adduction at the prosthetic knee, which was fully restrained, revealed an erroneous rotation as large as 30 degrees in one protocol. Higher correlations were observed between the protocols with similar biomechanical models, whereas little influence seems to be ascribed to the marker-set. Back to Top

Collins TD, Ghoussayni SN, Ewins DJ, Kent JA. 2009 A six degrees-of-freedom marker set for gait analysis: repeatability and comparison with a modified Helen Hayes set. 2009 - Gait & Posture. 2009 Aug;30(2):173-80. Kinematic gait analysis is limited by simplified marker sets and related models. The majority of sets in clinical use were developed with low resolution imaging systems so required various assumptions about body behaviour. Further major limitations include soft tissue artefact and ambiguity in landmark identification. An alternative is the use of sets based on six degrees-of-freedom (DOF) principles, primarily using marker clusters for tracking. This study evaluates performance of a 6DOF set, based largely on CAST/ISB recommendations, through comparison with a conventional set and assessment of repeatability. Ten healthy subjects were assessed in treadmill walking, with both sets applied simultaneously on two occasions. Data were analysed using repeatability coefficients, correlation of key features, and comparison of joint angle curves and difference curves with confidence bands. Apart from pelvic tilt all segment and joint angles from both sets showed high within and between session repeatability (CMC>0.80). Hip rotations showed clear differences between the two sets with indications in support of the 6DOF set. Knee coronal angles showed evidence of cross-talk in the conventional set, highlighting difficulties with anatomical identification despite control measures such as a foot alignment template. Knee transverse angles showed inconsistent patterns for both sets. At the ankle the conventional set only allowed true measurement in two planes so with high repeatability the 6DOF set is preferable. The 6DOF set showed comparable performance to the conventional set and overcomes a number of theoretical limitations, however further development is needed prior to clinical implementation.

Cappozzo A, Cappello A, Della Croce U, Pensalfini P. (1997) Surface-Marker Cluster Design Criteria for 3-D Bone Movement Reconstruction. 1997 - IEEE Transactions on Biomedical Engineering, 44 (12), p 1165-1174 When three-dimensional (3-D) human or animal movement is recorded using a photogrammetric system, bone-embedded frame positions and orientations are estimated from reconstructed surface marker trajectories using either nonoptimal or optimal algorithms. The effectiveness of these mathematical procedures in accommodating for both photogrammetric errors and skin movement artifacts depends on the number of markers associated with a given bone as well as on the size and shape characteristics of the relevant cluster. One objective of this paper deals with the identification of marker cluster design criteria aimed at the minimization of error propagation from marker coordinates to bone-embedded frame position and orientation. Findings allow for the quantitative estimation of these errors for any given cluster configuration and suggest the following main design criteria. A cluster made up of four markers represents a good practical compromise. Planar clusters are acceptable, provided in quasi-isotropic distribution. The root mean square distance of the markers from their centroid should be greater than ten times the standard deviation of the marker position error. The second objective of this paper deals with the identification of the optimal cluster position and orientation on the limb aimed at the minimization of error propagation to anatomical landmark laboratory coordinates. Cluster position should be selected to minimize skin movement artifacts. The longest principal axis of the marker distribution should be oriented toward the relevant anatomical landmark position.

Rainbow M, Buczek FL, Cooney KM, Walker MR, Sanders JO (2003) Differences between Vicon Clinical Manager and Visual3D3D Abstracts of the American Society of Biomechanics When switching biomechanical modeling software it is useful to note key differences between platforms. When using a given model like Helen Hayes, it is important that clinical decisions remain unaffected by software platform changes. This study showed no statistical difference between the Helen Hayes modeling in VCM and Visual3D for 16 out of 20 variables key to our gait analysis

Ferber R, McClay Davis I, Williams DS (2003) Gender differences in lower extremity mechanics during running Clinical Biomechanics 18: 350-357 OBJECTIVE: To compare differences in hip and knee kinematics and kinetics in male and female recreational runners. DESIGN: Gait analysis of 20 men and 20 women recreational runners. BACKGROUND: Female runners are reported to be more likely to sustain certain lower extremity injuries compared to their male counterparts. This has been attributed, in part, to differences in their structure and it has been postulated that these structural differences may lead to differences in running mechanics. It was hypothesized that females would exhibit greater peak hip adduction, hip internal rotation, knee abduction and decreased knee internal rotation compared to their male counterparts. It was also hypothesized that females would exhibit greater hip and knee negative work in the frontal and transverse planes compared to males. METHODS: Comparisons of hip and knee three-dimensional joint angles and negative work during the stance phase of running gait were made between genders. RESULTS: Female recreational runners demonstrated a significantly greater peak hip adduction, hip internal rotation and knee abduction angle compared to men. Female recreational runners also demonstrated significantly greater hip frontal and transverse plane negative work compared to male recreational runners. CONCLUSION: Female recreational runners exhibit significantly different lower extremity mechanics in the frontal and transverse planes at the hip and knee during running compared to male recreational runners. RELEVANCE: Understanding the differences in running mechanics between male and female runners may lend insight into the etiology of different injury patterns seen between genders. In addition, these results suggest that care should be taken to account for gender when studying groups of male and female recreational runners. Back to Top

Manal K, McLay I, Galinat B, Stanhope (2003) The accuracy of estimating proximal tibial translation during natural cadence walking: bone vs. skin mounted targets Clinical Biomechanics. 18, 126-131 OBJECTIVE: To assess the efficacy of estimating proximal tibial translation using video-based motion capture and an array of surface-mounted targets ideal for tracking motion of the tibia. DESIGN: Superficial and bone-anchored tracking targets were used to create two independent sets of data locating the proximal tibia in a global coordinate system. BACKGROUND: Knowledge of the effect that soft tissue movement has on estimates of proximal tibial translation has not been reported to date. This basic information is necessary to establish construct validity for any study proposing to document tibial translation using standard video-based motion capture methods. METHODS: A six camera motion capture system was used to collect surface-mounted and bone-anchored data for seven healthy adult subjects walking at a self-selected speed. The subjects walked along the positive Y-axis of the global reference system, with the positive Z-axis oriented vertically. RESULTS: Average peak differences in the location of the proximal tibia calculated from the bone and surface-mounted targets were 7.1, 3.7 and 2.1 mm along the X, Y and Z axes of the global coordinate system respectively. Individual subject peak differences were as large as 14.1, 11.8 and 8.3 mm along the X, Y and Z axes. CONCLUSIONS: Estimates of tibial translation with a measurement resolution better than 3 mm are not likely using standard motion capture methods and tracking targets attached superficially to the lower leg. RELEVANCE: The results of this study clearly depict the considerable effect that soft tissue motion of the lower leg has on estimates of proximal tibial translation. Without consideration for the difficulties in measuring femoral, or patellar motion, we believe it is not feasible to routinely obtain sufficiently accurate estimates of detailed knee joint translations using superficial tracking target attachment methods.

Manal K, McLay I, Richards J, Galinat B, Stanhope SJ (2002) Knee moment profiles during walking: errors due to soft tissue movement of the shank and the influence of the reference coordinate system Gait and Posture. 15, 10-17 The effect soft tissue movement of the shank had on knee joint moments during natural cadence walking was investigated in this study. This was examined by comparing knee moments determined from bone-anchored and surface mounted tracking targets. Six healthy adult subjects participated in this study. The largest difference (3 N m) occurred about the AP axis, with smaller differences of approximately 2 and 1 N m about the flexion/extension (F/E) and longitudinal (Long) axes, respectively. The magnitude of these differences would not likely affect the clinical interpretation of the data. The effect of reporting knee moments in two different orthogonal reference systems was also examined. The peak extension moment was significantly greater when expressed about an anatomical axis following the line of the malleoli than when the moment was reported about an axis parallel to the frontal plane of the shank. In contrast, the first peak abduction moment was significantly greater when expressed about an axis perpendicular to the frontal plane of the shank. Care should therefore be exercised whenever comparisons between studies are made in which the reference axes are not aligned.

Manal K, McLay I, Richards J, Galinat B, Stanhope SJ (2002) Knee moment profiles during walking: errors due to soft tissue movement of the shank and the influence of the reference coordinate system 2002 - Gait and Posture. 15, 10-17 The effect soft tissue movement of the shank had on knee joint moments during natural cadence walking was investigated in this study. This was examined by comparing knee moments determined from bone-anchored and surface mounted tracking targets. Six healthy adult subjects participated in this study. The largest difference (3 N m) occurred about the AP axis, with smaller differences of approximately 2 and 1 N m about the flexion/extension (F/E) and longitudinal (Long) axes, respectively. The magnitude of these differences would not likely affect the clinical interpretation of the data. The effect of reporting knee moments in two different orthogonal reference systems was also examined. The peak extension moment was significantly greater when expressed about an anatomical axis following the line of the malleoli than when the moment was reported about an axis parallel to the frontal plane of the shank. In contrast, the first peak abduction moment was significantly greater when expressed about an axis perpendicular to the frontal plane of the shank. Care should therefore be exercised whenever comparisons between studies are made in which the reference axes are not aligned. Manal, K., McClay, I., Stanhope, S., Richards, J., Galinat, B. (2000) Comparison of surface mounted markers and attachment methods in estimating tibial rotations during walking: an in vivo study 2000 - Gait and Posture 11:38-45 The overall goal of this work was to determine an optimal surface-tracking marker set for tracking motion of the tibia during natural cadence walking. Eleven different marker sets were evaluated. The marker sets differed in the location they were attached to the shank, the method used to attach the marker sets to the segment and the physical characteristics of the marker sets. Angular position during stance for each marker set was expressed relative to the orientation of the tibia as measured using bone anchored markers. A marker set consisting of four markers attached to a rigid shell positioned over the distal lateral shank and attached to the leg using an underwrap attachment yielded the best estimate of tibial rotation. Rotational deviations of±2° about the medio–lateral and antero–posterior axes, and±4° about the longitudinal axis did occur even when using the optimal set of markers.

Karlsson D, Tranberg R (1999) On skin movement artifact-resonant frequencies of skin markers attached to the leg. 1999 - Human Movement Science 18:627-635 In this paper, some dynamic effects of the relative motion between the skin and the underlying bone – skin movement artefact – are presented. Two parameters were investigated: (1) the local stiffness of different attachment sites along the leg and (2) the resonant frequencies of wand marker systems. The tangential stiffness was found to vary between 330 and 1900 N/m with the smallest stiffness found in the anterior/posterior direction on the proximal thigh. The highest stiffness measured was in the proximal–distal direction at the knee. The resonant frequencies of wand markers placed on the leg were found to be typically 23–51 Hz, depending on the mass of the marker. The effect of keeping the muscles tensed was also measured. Increased muscle tension provided a more stable base, producing increased stiffness.

Fuller J, Lui LJ, Murphy MC, Mann RW (1997) A comparison of lower- extremity skeletal kinematics measured using skin- and pin mounted markers. 1997 - Human Movement Science 16:219-242 Measurement of three-dimensional, skeletal kinematics is important for clinicians and engineers alike. Most in vivo motion data are acquired using skin-mounted markers or marker arrays. Experiments were carried out to quantitatively evaluate the validity of using skin-mounted markers to measure the three-dimensional kinematics of the underlying bone. Kinematic data for marker arrays mounted on skeletal pins screwed directly into the bone were compared with data for markers, and arrays of markers, mounted on the skin. Findings included: (1) Task-dependent soft tissue motion relative to the underlying bone of up to twenty millimeters was measured; (2) The accuracy of segmental rigid body velocity estimates was inadequate for determining instantaneous helical axis (IHA) parameters; (3) Power spectra for skin- and pin-mounted arrays cover similar frequency bands and there was no evidence of a distinct, frequency domain soft tissue artifact; (4) Joint angles calculated from the relative rotation of skin-mounted arrays had significant differences compared to the expected values due to soft tissue effects; and (5) Skin-mounted marker data exhibited a transient response to heel strike in gait, but for low-mass markers the transient was well-damped and could be removed with optimal smoothing.

Reinschmidt C, van den Bogert AJ, Nigg BM, Lundberg A, Murphy N (1997) Effect of skin movement on the analysis of skeletal knee joint motion during running. 1997 - Journal of Biomechanics 30(7):729-732 It is not known how well skin markers represent the skeletal knee joint motion during running. Hence, the purpose of this investigation was to compare the skin marker derived tibiofomoral motion with the skeletal tibiofemoral motion during running. In addition to skin markers attached to the shank and thigh, triads of reflective markers were attached to bone pins inserted into the tibia and femur. Three-dimensional kinematics of the stance phase of five running trials were recorded for three subjects using high-speed cine cameras (200 Hz). The knee motion was expressed in terms of Cardan angles calculated from both the external and skeletal markers. Good agreement was present between the skin and bone marker based knee flexion/extension. For abduction/adduction and internal/external knee rotation, the difference between skeletal and external motion was large compared to the amplitude of these motions. Average errors relative to the range of motion during running stance were 21% for flexion/extension, 63% for internal/external rotation, and 70% for abduction/adduction. The errors were highly subject dependent preventing the realization of a successful correction algorithm. It was concluded that knee rotations other than flexion/extension may be affected with substantial errors when using skin markers.

Holden JP, Orsini JA, Siegel KL, Kepple TM, Gerber LH, Stanhope SJ (1997) Surface movement errors in kinematic and kinetic measurement in gait. 1997 - Gait and Posture. The movement of surface mounted targets (SMT) on a shell at the mid-shank and of bone mounted targets attached to the distal shank using a Percutaneous Skeletal Tracker (PST) were simultaneously measured during free-speed walking of three adult subjects having different body types. Surface movement errors in shank kinematic estimates were determined by expressing the segmental motion derived from the SMT relative to the PST-based segment coordinate system (SCS) located at the segment center of gravity. The greatest errors were along and around the shank longitudinal axis, with peak magnitudes of 10 mm of translation and 8° of rotation in one subject. Estimates of knee joint center locations differed by less than 11 mm in each SCS direction. Differences in estimates of net knee joint forces and moments were most prominent during stance phase, with magnitudes up to 39 N in the shank mediolateral direction and 9 N.m about the mediolateral axis. The differences in kinetics were primarily related to the effect of segment position and orientation on the expression of joint forces and on the magnitude and expression of joint moments.

Ball KA, Pierrynowski MR. (1996) Classification of errors in locating a rigid body. 1996 - Journal of Biomechanics 29(9):1213-1217 This paper discusses the manner in which random Gaussian errors affect the determination of body segment kinematics. For the process of modelling rigid body (RB) motion, three types of kinematic errors, input, measured and theoretical, are identified. These correspond to errors in: the determination of three-dimensional observed points, the RB fit of those points, and the estimation of true RB positions, respectively. Of these, the theoretical error is most critical and most pivotal. Accuracy is provided when the theoretical error is minimised, yet only the measured error can be minimised by RB modelling algorithms. In computer simulations one may determine the effect that such manipulations have on theoretical error, yet in most experimental conditions this value may not even be calculated. Fortunately, computer simulations can be performed to determine the inter-relationships between the types of RB modelling errors. Such simulations can also be used to investigate the effects of RB shape. In this paper, Monte Carlo simulations were performed on three unit radius RBs; a triangle, a square and a tetrahedron. Although use of the triangle provided the lowest measured error, this also coincided with the greatest theoretical error. The use of redundant points was found to yield superior theoretical accuracies. A slight advantage was gained with use of the non-planar point arrangement on the tetrahedron, both the measured and theoretical errors were reduced. Finally, the superiority of RB modelling over individual point tracking was reflected in all of the results; between 33 and 50% of the input error was eliminated with the use of RB modelling.

Angeloni C, Cappozzo A, Catani F, Leardini A (1993) Quantification of relative displacement of skin- and plate-mounted markers with respect to bones. 1993 - Journal of Biomechanics 26:864 Background : Soft tissue artefact is the most invalidating source of error in human motion analysis using optoelectronic stereo- photogrammetry. It is caused by the erroneous assumption that markers attached to the skin surface are rigidly connected to the underlying bones. The quantification of this artefact in three dimensions and the knowledge of how it propagates to relevant joint angles is necessary for the interpretation of gait analysis data. Methods : Two subjects, treated by total knee replacement, underwent data acquisition simultaneously with fluoroscopy and stereophotogrammetry during stair climbing, step up/down, sit-to-stand/stand-to-sit, and extension against gravity. The reference 3D kinematics of the femur and tibia was reconstructed from fluoroscopy-based tracking of the relevant prosthesis components. Soft tissue artefact was quantified as the motion of a grid of retro-reflecting makers attached to the thigh and shank with respect to the underlying bones, tracked by optoelectronic stereophotogrammetry. The propagation of soft tissue artefact to knee rotations was also calculated. Findings : The standard deviation of skin marker trajectory in the corresponding prosthesis-embedded anatomical frame was found up to 31 mm for the thigh and up to 21 mm for the shank. The ab/adduction and internal/external rotation angles were the most affected by soft tissue artefact propagation, with root mean square errors up to 192% and 117% of the corresponding range, respectively. Interpretations : In both the analysed subjects the proximal thigh showed the largest soft tissue artefact. This is subject- and task- specific. However, larger artefact does not necessarily produce larger propagated error on knee rotations. Propagated errors were extremely critical on ab/adduction and internal/external rotation. These large errors can nullify the usefulness of these variables in the clinical interpretation of gait analysis.

Cappello, A., Cappozzo, A., La Palombara, P.F., Lucchetti, L., Leardini, A. (1997) Multiple anatomical landmark calibration for optimal bone pose estimation. 1997 - Human Movement Science. 16: 259-274 Bone motion estimation by means of photogrammetric, non-invasive methods can be severely corrupted by experimental errors. The largest fraction of such errors is associated with the relative movement between externally located markers and the underlying bone, due to the interposition of both passive and active soft tissues. The errors affecting the estimates of anatomical landmarks trajectories in the laboratory frame can be considerably reduced by following the Calibrated Anatomical System Technique protocol which entails: (i) a static calibration of the anatomical landmarks in a technical reference frame defined by the cluster of skin markers, and (ii) the use of of a rigid model of the cluster. This paper illustrates how a modification of the above-mentioned protocol, involving a multiple calibration of the anatomical landmarks in different postures, and the use of a deformable model of the cluster, can effectively enhance bone motion estimation. In order to validate the new protocol a cycling test on a patient wearing a femoral external fixator was performed. The root mean square reconstruction error (RMSE) on an anatomical landmark (greater trochanter) trajectory drops from over 15 mm to less than 10 mm while the RMSEs of the bone (femur) orientation and position decrease respectively from about 5 deg and 7 mm with our previous protocol to less than 4 deg and 4.5 mm. The improvements are even more significant when movement components relative to the main planes and axes of motion are considered. Back to Top

Buczek FL1, Rainbow MJ, Cooney KM, Walker MR, Sanders JO (2010) Implications of using hierarchical and six degree-of-freedom models for normal gait analyses. Gait & Posture. 2010 Jan;31(1):57-63 Hierarchical biomechanical models (conventional gait model, CGM) are attractive because of simple data collection demands, yet they are susceptible to errors that are theoretically better controlled using six degree-of-freedom models that track body segments independently (OPT1). We wished to compare gait variables obtained with these models. Twenty-five normal children walked while wearing a hybrid marker configuration, permitting identical strides to be analyzed using CGM and OPT1. Kinematics and ground reaction forces were obtained using a common motion capture system. CGM and OPT1 were implemented in Visual3D software, where inverse dynamics provided 20 clinically relevant gait variables (joint angles, moments and powers). These were compared between models using dependent t-tests (Bonferroni-adjusted alpha of 0.0025), and ensemble averages. We hypothesized that OPT1 would provide data similar to CGM in the sagittal plane, and different from CGM in coronal and transverse planes. Six variables were significantly different in the sagittal plane, suggesting that CGM produced a more extended lower extremity; this was explained by a posterior bias to the lateral knee marker during knee flexion, as a result of skin movement artifact. No significant differences were found in coronal plane variables. Four variables were significantly different in the transverse plane. Ensemble averages were comparable between models. For normal children, biomechanical interpretations based upon these tested variables are unlikely to change due to independent segment tracking alone (CGM vs. OPT1). Additional differences may appear due to pathology, and when segment reference frames are changed from those used in CGM to reflect individual anatomy. Back to Top

Whatling GM1, Evans SL, Holt CA. (2009) Comparing different data collection and analysis techniques for quantifying healthy knee joint function during stair ascent and descent. Proc Inst Mech Eng H. 2009 Nov;223(8):981-90. There is currently no standard data collection or analysis method for the assessment of stair gait using motion analysis. This makes the comparison of results from different studies difficult. It is important to gain an appreciation of the discrepancies in kinematic and kinetic information generated by employing different computational approaches, as these differences may be critical in cases where methodologies were to change over a long-term study. This study explores the effect of using different methodologies for the assessment of non-pathological knee function of ten subjects during stair ascent and descent. Two methods of computing knee kinematics were compared: (a) using in-house software and a pointer method of anatomical calibration and (b) using commercial software, Visual3D (C-motion, Inc.) and skin-mounted markers. Significant differences were found between the two methods when calculating a frontal plane range of motion (p < 0.05). Three methods of computing knee moments were compared. Knee moments computed using the inverse dynamic analysis (IDA) approach of Visual3D (C-motion, Inc.) were significantly different (p < 0.05) to those calculated using in-house IDA software that ignores the foot and ankle and to those computed using a vector cross-product approach. This study highlights the implications of comparing data generated from different collection and analysis methods.
Back to Top

Deluzio KJ, Astephen JL. (2007) Biomechanical features of gait waveform data associated with knee osteoarthritis: An application of principal component analysis. Gait & Posture. Jan 25(1):86-93. This study compared the gait of 50 patients with end-stage knee osteoarthritis to a group of 63 age-matched asymptomatic control subjects. The analysis focused on three gait waveform measures that were selected based on previous literature demonstrating their relevance to knee osteoarthritis (OA): the knee flexion angle, flexion moment, and adduction moment. The objective was to determine the biomechanical features of these gait measures related to knee osteoarthritis. Principal component analysis was used as a data reduction tool, as well as a preliminary step for further analysis to determine gait pattern differences between the OA and the control groups. These further analyses included statistical hypothesis testing to detect group differences, and discriminant analysis to quantify overall group separation and to establish a hierarchy of discriminatory ability among the gait waveform features. The two groups were separated with a misclassification rate (estimated by cross-validation) of 8%. The discriminatory features of the gait waveforms were, in order of their discriminatory ability: the amplitude of the flexion moment, the range of motion of the flexion angle, the magnitude of the flexion moment during early stance, and the magnitude of the adduction moment during stance.

Benedetti MG, Merlo A, Leardini A. (2013) Inter-laboratory consistency of gait analysis measurements. Gait & Posture. Sep;38(4):934-9. The dissemination of gait analysis as a clinical assessment tool requires the results to be consistent, irrespective of the laboratory. In this work a baseline assessment of between site consistency of one healthy subject examined at 7 different laboratories is presented. Anthropometric and spatio-temporal parameters, pelvis and lower limb joint rotations, joint sagittal moments and powers, and ground reaction forces were compared. The consistency between laboratories for single parameters was assessed by the median absolute deviation and maximum difference, for curves by linear regression. Twenty-one lab-to-lab comparisons were performed and averaged. Large differences were found between the characteristics of the laboratories (i.e. motion capture systems and protocols). Different values for the anthropometric parameters were found, with the largest variability for a pelvis measurement. The spatio-temporal parameters were in general consistent. Segment and joint kinematics consistency was in general high (R2>0.90), except for hip and knee joint rotations. The main difference among curves was a vertical shift associated to the corresponding value in the static position. The consistency between joint sagittal moments ranged form R2=0.90 at the ankle to R2=0.66 at the hip, the latter was increasing when comparing separately laboratories using the same protocol. Pattern similarity was good for ankle power but not satisfactory for knee and hip power. The force was found the most consistent, as expected. The differences found were in general lower than the established minimum detectable changes for gait kinematics and kinetics for healthy adults.

Leardini A, Sawacha Z, Paolini G, Ingrosso S, Nativo R, Benedetti MG.(2007) A new anatomically based protocol for gait analysis in children. Gait & Posture. 2007 Oct;26(4):560-71 Human movement analysis still suffers from the weakness of the currently used protocols for data collection and reduction. Reliable data comparisons and precise functional assessment require anatomically based definitions of the reference axes and frames, and therefore careful identification and tracking of the landmarks. When impaired children are analysed, the marker-set and other measurement procedures have to be minimised to reduce the time of the experiment and ensure patient collaboration. A new protocol is proposed for the analysis of pelvis and lower limb motion obtained as a compromise between these two requirements. A marker-set is proposed which involves the attachment of 22 skin markers, the calibration by a pointer of 6 anatomical landmarks, and the identification of the hip joint centre by a prediction approach. Anatomical reference frames and joint rotations are defined according to current recommendations. The protocol was assessed by analysing a single child in several repetitions by different examiners, and a population of 10 healthy children, mean age 9.7-years-old. The entire analysis was repeated after subtraction of the offset by static posture angles. The minimum and maximum means of the standard deviations from five examiners of the same child were respectively 2.1 degrees in pelvic obliquity and 6.8 degrees in knee rotation. The minimum and maximum means of the standard deviations from the 10 healthy children were 2.1 degrees in pelvic obliquity and 9.6 degrees in knee internal-external rotation. The protocol is feasible and allows 3D anatomical-based measurements of segment and joint motion and data sharing according to current standards.

Ingrosso S, Benedetti MG, Leardini A, Casanelli S, Sforza T, Giannini S.(2009) GAIT analysis in patients operated with a novel total ankle prosthesis. Gait & Posture. 2009 Aug;30(2):132-7. A new three-part total ankle prosthesis was designed recently to restore natural joint motion while maintaining full congruity of the articulating surfaces. This was achieved by replicating natural function for the ligaments. Early functional recovery was assessed in the present study in patients who underwent replacement with this prosthesis. This was undertaken using the AOFAS clinical scoring system and gait analysis, performed preoperatively and at 6 and 12 months from surgery. The 10 patients had, at the time of operation, a mean age of 57.4 years (range 45-72), and BMI 25.8 (range 20.4-34.1). A recently proposed protocol for three-dimensional and anatomically based analysis of joint kinematics and kinetics was used. The AOFAS score rose from 44.3 pre-op to 81.5 and 81.0 respectively at 6- and 12-month follow-up, with particular improvement in function. Spatio-temporal parameters improved considerably already at 6 months. More normal patterns and ranges of rotations and moments were observed in the three anatomical planes of the replaced ankle at 6 months and maintained at 12 months. In particular the improvement in dorsi-plantarflexion range in stance was significant, though a limited plantarflexion in swing occurred. EMG revealed a good recovery of physiological activity for the biceps femoris at 12-month follow-up. The new ankle prosthesis contributed to early functional recovery at 6 months, maintained at 1 year.

Conti G, Cristofolini L, Juszczyk M, Leardini A, Viceconti M.(2008) Comparison of three standard anatomical reference frames for the tibia-fibula complex. J Biomech. 2008 Dec 5;41(16):3384-9. Definition of anatomical reference frames is necessary both for in vitro biomechanical testing, and for in vivo human movement analyses. Different reference frames have been proposed in the literature for the lower limb, and in particular for the tibia-fibula complex. The scope of this work was to compare the three most commonly referred proposals (proposed by [Ruff, C.B., Hayes, W.C., 1983. Cross-sectional geometry at Pecos Pueblo femora and tibiae -A biomechanical investigation: I. method and general patterns of variation. American Journal of Physical Anthropology 60, pp. 359-381.], by [Cappozzo, A., Catani, F., Della Croce, U., Leardini, A., 1995. Position and orientation in space of bones during movement: anatomical frame definition and determination. Clinical Biomechanics (Bristol, Avon) 10, pp. 171-178.], and by the Standardization and Terminology Committee of the International Society of Biomechanics, [Wu, G., Siegler, S., Allard, P., Kirtley, C., Leardini, A., Rosenbaum, D., Whittle, M., D'Lima, D.D., Cristofolini, L., Witte, H., Schmid, O., Stokes, I., 2002. ISB recommendation on definitions of joint coordinate system of various joints for reporting of human joint motion-part I: ankle, hip and spine. International Society of Biomechanics. Journal of Biomechanics 35, pp. 543-548.]). These three frames were identified on six cadaveric tibia-fibula specimens based on the relevant anatomical landmarks, using a high-precision digitizer. The intra-operator (ten repetitions) and inter-operator (three operators) repeatability were investigated in terms of reference frame orientation. The three frames had similar intra-operator repeatability. The reference frame proposed by Ruff et al. had a better inter-operator repeatability (this must be put in relation with the original context of interest, i.e. in vitro measurements on dissected bones). The reference frames proposed by Ruff et al. and by ISB had a similar alignment; the frame proposed by Cappozzo et al. was considerably externally rotated and flexed with respect to the other two. Thus, the reference frame proposed by Ruff et al. is preferable when the full bone surface is accessible (typically during in vitro tests). Conversely, no advantage in terms of repeatability seems to exist between the reference frames proposed by Cappozzo et al. and ISB.

Ferrari A, Benedetti MG, Pavan E, Frigo C, Bettinelli D, Rabuffetti M, Crenna P, Leardini A.(2008) Quantitative comparison of five current protocols in gait analysis. Gait & Posture. 2008 Aug;28(2):207-16 Data collection and reduction procedures, coherently structured in protocols, are necessary in gait analysis to make kinematic and kinetic measurements clinically comprehensible. The current protocols differ considerably for the marker-set and for the biomechanical model implemented. Nevertheless, conventional gait variables are compared without full awareness of these differences. A comparison was made of five worldwide representative protocols by analysing kinematics and kinetics of the trunk, pelvis and lower limbs exactly over the same gait cycles. A single comprehensive arrangement of markers was defined by merging the corresponding five marker-sets. This resulted in 60 markers to be positioned either on the skin or on wands, and in 16 anatomical landmark calibrations to be performed with an instrumented pointer. Two healthy subjects and one patient who had a special two degrees of freedom knee prosthesis implanted were analysed. Data from up-right posture and at least three gait repetitions were collected. Five corresponding experts participated in the data collection and analysed independently the data according to their own procedures. All five protocols showed good intra-protocol repeatability. Joint flexion/extension showed good correlations and a small bias among protocols. Out-of-sagittal plane rotations revealed worse correlations, and in particular knee abduction/adduction had opposite trends. Joint moments compared well, despite the very different methods implemented. The abduction/adduction at the prosthetic knee, which was fully restrained, revealed an erroneous rotation as large as 30 degrees in one protocol. Higher correlations were observed between the protocols with similar biomechanical models, whereas little influence seems to be ascribed to the marker-set.

Manca M, Ferraresi G, Cosma M, Cavazzuti L, Morelli M, Benedetti MG.(2014) Gait patterns in hemiplegic patients with equinus foot deformity. Biomed Res Int. 2014;2014:939316 Equinus deformity of the foot is a common feature of hemiplegia, which impairs the gait pattern of patients. The aim of the present study was to explore the role of ankle-foot deformity in gait impairment. A hierarchical cluster analysis was used to classify the gait patterns of 49 chronic hemiplegic patients with equinus deformity of the foot, based on temporal-distance parameters and joint kinematic measures obtained by an innovative protocol for motion assessment in the sagittal, frontal, and transverse planes, synthesized by parametrical analysis. Cluster analysis identified five subgroups of patients with homogenous levels of dysfunction during gait. Specific joint kinematic abnormalities were found, according to the speed of progression in each cluster. Patients with faster walking were those with less ankle-foot complex impairment or with reduced range of motion of ankle-foot complex, that is with a stiff ankle-foot complex. Slow walking was typical of patients with ankle-foot complex instability (i.e., larger motion in all the planes), severe equinus and hip internal rotation pattern, and patients with hip external rotation pattern. Clustering of gait patterns in these patients is helpful for a better understanding of dysfunction during gait and delivering more targeted treatment. Back to Top

Caravaggia P, Matias AB, Taddei UT, Ortolani M, Leardini A, Sacco I (2019) Reliability of medial-longitudinal-arch measures for skin-markers based kinematic analysis J Biomech The medial-longitudinal arch (MLA) is perhaps the most important feature characterizing foot morphology. While current skin-markers based models of the MLA angle used in stereophotogrammetry allow to estimate foot arch shape and deformation, these do not always appear consistent with foot anatomy and with standard clinical definitions. The aim of this study was to propose novel skin-markers based measures of MLA angle and investigate their reliability during common motor tasks. Markers on the calcaneus, navicular tuberosity, first metatarsal head and base, and on the two malleoli were exploited to test eight definitions of MLA angle consistent with foot anatomy, both as angles between two 3-dimensional vectors and as corresponding projections on the sagittal plane of the foot. The inter-trial, inter-session and inter-examiner reliability of each definition was assessed in multiple walking and running trials of two volunteers, tested by four examiners in three sessions. Inter-trial variability in walking was in the range 0.7–1.2 deg, the inter-session 2.8–7.5 deg, and the inter-examiner in the range 3.7–9.3 deg across all MLA definitions. The Rizzoli Foot Model definition showed the lowest inter-session and inter-examiner variability. MLA measures presented similar variability in walking and running. This study provides preliminary information on the reliability of MLA measurements based on skin-markers. According to the present study, angles between 3-dimensional vectors and minimal marker sets should be preferred over sagittal-plane projections. Further studies should be sought to investigate which definition is more accurate with respect to the real MLA deformation in different loading conditions.

Giacomozzi C, Leardini A, Caravaggi P.(2014) Correlates between kinematics and baropodometric measurements for an integrated in-vivo assessment of the segmental foot function in gait. J Biomech. 2014 Aug 22;47(11):2654-9. Baropodometry and multi-segmental foot kinematics are frequently employed to obtain insight into the mechanics of the foot-ground interaction in both basic research and clinical settings. However, nothing hitherto has been reported on the full integration of kinematics with baropodometric parameters, and only a few studies have addressed the association between intersegmental kinematics and plantar loading within specific foot regions. The aim of this study was to understanding the relationships between foot joint mobility and plantar loading by focusing on the correlation between these two measures. An integrated pressure-force-kinematics system was used to measure plantar pressure and rotations between foot segments during the stance phase of walking in 10 healthy subjects. An anatomically-based mask was applied to each footprint to obtain six regions according to the position of the markers; hence each kinematic segment was paired with a corresponding area of the plantar surface. Relationships between segmental motion and relevant baropodometric data were explored by means of correlation analysis. Negative, weak-to-moderate correlations (R(2)<0.5) were found between pressure (mean and peak) and inter-segmental range of motion across all foot joints except the Calcaneus-Midfoot. Temporal profiles of sagittal-plane kinematics and baropodometric parameters were well correlated, particularly at the ankle joint. Larger motion in the foot joints during walking was associated with lower plantar pressure in almost all regions. The study helps improve our understanding of the relationship between joint mobility and plantar loading in the healthy foot and represents a critical preliminary analysis before addressing possible clinical applications.

Carter SL, Sato N, Hopper LS (2017) Kinematic repeatability of a multi-segment foot model for dance. Sports Biomech. 2017 Jul 21:1-19. The purpose of this study was to determine the intra and inter-assessor repeatability of a modified Rizzoli Foot Model for analysing the foot kinematics of ballet dancers. Six university-level ballet dancers performed the movements; parallel stance, turnout plié, turnout stance, turnout rise and flex-point-flex. The three-dimensional (3D) position of individual reflective markers and marker triads was used to model the movement of the dancers' tibia, entire foot, hindfoot, midfoot, forefoot and hallux. Intra and inter-assessor reliability demonstrated excellent (ICC ≥ 0.75) repeatability for the first metatarsophalangeal joint in the sagittal plane. Intra-assessor reliability demonstrated excellent (ICC ≥ 0.75) repeatability during flex-point-flex across all inter-segmental angles except for the tibia-hindfoot and hindfoot-midfoot frontal planes. Inter-assessor repeatability ranged from poor to excellent (0.5 > ICC ≥ 0.75) for the 3D segment rotations. The most repeatable measure was the tibia-foot dorsiflexion/plantar flexion articulation whereas the least repeatable measure was the hindfoot-midfoot adduction/abduction articulation. The variation found in the inter-assessor results is likely due to inconsistencies in marker placement. This 3D dance specific multi-segment foot model provides insight into which kinematic measures can be reliably used to ascertain in vivo technical errors and/or biomechanical abnormalities in a dancer's foot motion.

Dingenen B, Deschamps K, Delchambre F, Van Peer E, Staes FF, Matricali GA. (2017) Effect of taping on multi-segmental foot kinematic patterns during walking in persons with chronic ankle instability J Sci Med Sport. 2017 Sep;20(9):835-840. OBJECTIVES: To evaluate multi-segmental foot kinematic patterns in chronic ankle instability (CAI) participants during walking, and to investigate the influence of high-Dye and low-Dye taping on these kinematic patterns. DESIGN: Cross-sectional study. METHODS: Kinematic data of 12 non-injured controls and 15 CAI participants were measured with a three-dimensional motion analysis system during barefoot walking. In addition, the CAI participants walked with high-Dye and low-Dye taping. A rigid Plug-in gait model and the Rizzoli 3D Multi-Segment Foot Model were used to measure multi-segmental foot kinematic patterns. One-dimensional statistical parametric mapping was used to compare barefoot walking of the control and CAI group, and to evaluate differences between walking barefoot and walking with high-Dye and low-Dye taping within the CAI group. RESULTS: Compared to the control group, CAI participants showed a decreased ankle dorsiflexion during loading response (p=0.025) and a more inverted calcaneus in relation to the shank during the initial swing phase (p=0.024). A more inverted position of the metatarsus in relation to the midfoot was observed after low-Dye taping during almost the entire stance phase (p=0.017). No significant differences were found for high-Dye taping. CONCLUSIONS: Significant differences in kinematic patterns were found in the ankle joint and rearfoot, but not in the mid- and forefoot in CAI participants. The application of low-Dye taping resulted in a significantly increased inverted position of the forefoot, which can be considered as a less desirable effect for patients with CAI. No other effects of high-Dye and low-Dye taping on kinematic patterns were revealed.

Leardini A, Aquila A, Caravaggi P, Ferraresi C, Giannini S. (2014)   “Multi-segment foot mobility in a hinged ankle-foot orthosis: the effect of rotation axis position.” Gait & Posture. 2014 May;40(1):274-7. Hinged ankle-foot orthoses are prescribed routinely for the treatment of ankle joint deficits, despite the conflicting outcomes and the little evidence on their functional efficacy. In particular, the axis of rotation of the hinge is positioned disregarding the physiological position and orientation. A multi-segment model was utilized to assess in vivo the effect of different positions for this axis on the kinematics of foot joints. A special custom-made hinged orthosis was manufactured via standard procedures for a young healthy volunteer. Four locations for the mechanical axis were obtained by a number of holes where two nuts and bolts were inserted to form the hinge: a standard position well above the malleoli, at the level of the medial malleolus, at the level of the lateral malleolus, and the physiological between the two malleoli. The shank and foot were instrumented with 15 reflective markers according to a standard protocol, and level walking was collected barefoot and with the orthosis in the four mechanical conditions. The spatio-temporal parameters observed in the physiological axis condition were the closest to normal barefoot walking. As expected, ankle joint rotation was limited to the sagittal plane. When the physiological axis was in place, rotations of the ankle out-of-sagittal planes, and of all other foot joints in the three anatomical planes, were found to be those most similar to the natural barefoot condition. These preliminary measures of intersegmental kinematics in a foot within an ankle-foot orthosis showed that only a physiological location for the ankle mechanical hinge can result in natural motion at the remaining joints and planes.

Eerdekens M, Staes F, Pilkington T and Deschamps K(2017) “A novel magnet based 3D printed marker wand as basis for repeated in-shoe multi segment foot analysis: a proof of concept.” Journal of Foot and Ankle Research (2017) 10:38. Abstract: Background: Application of in-shoe multi-segment foot kinematic analyses currently faces a number of challenges, including: (i) the difficulty to apply regular markers onto the skin, (ii) the necessity for an adequate shoe which fits various foot morphologies and (iii) the need for adequate repeatability throughout a repeated measure condition. The aim of this study therefore was to design novel magnet based 3D printed markers for repeated in-shoe measurements while using accordingly adapted modified shoes for a specific multi-segment foot model. Methods: Multi-segment foot kinematics of ten participants were recorded and kinematics of hindfoot, midfoot and forefoot were calculated. Dynamic trials were conducted to check for intra and inter-session repeatability when combining novel markers and modified shoes in a repeated measures design. Intraclass correlation coefficients were calculated to determine reliability. Results: Both repeatability and reliability were proven to be good to excellent with maximum joint angle deviations of 1.11° for intra-session variability and 1.29° for same-day inter-session variability respectively and ICC values of >0.91. Conclusion: The novel markers can be reliably used in future research settings using in-shoe multi-segment foot kinematic analyses with multiple shod conditions.

Deschamps K, Staes F, Bruyninckx H, Busschots E, Jaspers E, Atre A, Desloovere K.(2012)   “Repeatability in the assessment of multi-segment foot kinematics.” Gait & Posture. 2012 Feb;35(2):255-60. A recently published systematic review on 3D multi-segment foot models has illustrated the lack of repeatability studies providing evidence for appropriate clinical decision making. The aim of the current study was to assess the repeatability of the recently published model developed by Leardini et al. [10]. Foot kinematics of six healthy adults were analyzed through a repeated-measures design including two therapists with different levels of experience and four test sessions. For the majority of the parameters moderate or good repeatability was observed for the within-day and between-day sessions. A trend towards consistently higher within- and between-day variability was observed for the junior compared to the senior clinician. The mean inter-session variability of the relative 3D rotations ranged between 0.9-4.2° and 1.6-5.0° for respectively the senior and junior clinician whereas for the absolute angles this variability increased to respectively 2.0-6.2° and 2.6-7.8°. Mean inter-therapist standard deviations ranged between 2.2° and 6.5° for the relative 3D rotations and between 2.8° and 7.6° for the absolute 3D rotations. The ratio of inter-therapist to inter-trial errors ranged between 1.8 and 5.5 for the relative 3D rotations and between 2.4 and 9.7 for the absolute 3D rotations. Absolute angle representation of the planar angles was found to be more difficult. Observations from the current study indicate that an adequate normative database can be installed in gait laboratories, however, it should be stressed that experience of therapists is important and gait laboratories should therefore be encouraged to put effort in training their clinicians.

Powell DW, Williams DS, Butler RJ. (2013)   “A comparison of two multisegment foot models in high-and low-arched athletes.” J Am Podiatr Med Assoc. 2013 Mar-Apr;103(2):99-105. Malalignment and dysfunction of the foot have been associated with an increased propensity for overuse and traumatic injury in athletes. Several multisegment foot models have been developed to investigate motions in the foot. However, it remains unknown whether the kinematics measured by different multisegment foot models are equivocal. The purpose of the present study is to examine the efficacy of two multisegment foot models in tracking aberrant foot function. METHODS: Ten high-arched and ten low-arched female athletes walked and ran while ground reaction forces and three-dimensional kinematics were tracked using the Leardini and Oxford multisegment foot models. Ground reaction forces and joint angles were calculated with Visual 3D (C-Motion Inc, Germantown, MD). Repeated-measures analyses of variance were used to analyze peak eversion, time to peak eversion, and eversion excursions. RESULTS: The Leardini model was more sensitive to differences in peak eversion angles than the Oxford model. However, the Oxford model detected differences in eversion excursion values that the Leardini model did not detect. CONCLUSIONS: Although both models found differences in frontal plane motion between high- and low-arched athletes, the Leardini multisegment foot model is suggested to be more appropriate as it directly tracks frontal plane midfoot motion during dynamic motion.

Arnold JB, Mackintosh S, Jones S, Thewlis D. (2013)   “Repeatability of stance phase kinematics from a multi-segment foot model in people aged 50 years and older.” Gait & Posture. 2013 Jun;38(2):349-51.. Confidence in 3D multi-segment foot models has been limited by a lack of repeatability data, particularly in older populations that may display unique functional foot characteristics. This study aimed to determine the intra and inter-observer repeatability of stance phase kinematic data from a multi-segment foot model described by Leardini et al. [2] in people aged 50 years or older. Twenty healthy adults participated (mean age 65.4 years SD 8.4). A repeated measures study design was used with data collected from four testing sessions on two days from two observers. Intra (within-day and between-day) and inter-observer coefficient of multiple correlations revealed moderate to excellent similarity of stance phase joint range of motion (0.621-0.975). Relative to the joint range of motion (ROM), mean differences (MD) between sessions were highest for the within-day comparison for all planar ROM at the metatarsus-midfoot articulation (sagittal plane ROM 5.2° vs. 3.9°, MD 3.1°; coronal plane ROM 3.9 vs. 3.1°, MD 2.3°; transverse plane ROM 6.8° vs. 5.16°, MD 3.5°). Consequently, data from the metatarsus-midfoot articulation in the Istituto Ortopedico Rizzoli (IOR) foot model in adults aged over 50 years needs to be considered with respect to the findings of this study.

Deschamps K, Staes F, Bruyninckx H, Busschots E, Matricali GA, Spaepen P, Meyer C, Desloovere K. (2012)   “Repeatability of a 3D multi-segment foot model protocol in presence of foot deformities.” Gait & Posture. 2012 Jul;36(3):635-8. Repeatability studies on 3D multi-segment foot models (3DMFMs) have mainly considered healthy participants which contrasts with the widespread application of these models to evaluate foot pathologies. The current study aimed at establishing the repeatability of the 3DMFM described by Leardini et al. in presence of foot deformities. Foot kinematics of eight adult participants were analyzed using a repeated-measures design including two therapists with different levels of experience. The inter-trial variability was higher compared to the kinematics of healthy subjects. Consideration of relative angles resulted in the lowest inter-session variability. The absolute 3D rotations between the Sha-Cal and Cal-Met seem to have the lowest variability in both therapists. A general trend towards higher σ(sess)/σ(trial) ratios was observed when the midfoot was involved. The current study indicates that not only relative 3D rotations and planar angles can be measured consistently in patients, also a number of absolute parameters can be consistently measured serving as basis for the decision making process.

Benedetti MG, Manca M, Ferraresi G, Boschi M, Leardini A.(2011)   “A new protocol for 3D assessment of foot during gait: application on patients with equinovarus foot.” Clin Biomech (Bristol, Avon). 2011 Dec;26(10):1033-8. BACKGROUND: The aim of this study is to assess the clinical value of a recently introduced original protocol for full three dimensional analysis of ankle rotations in patients with equinovarus foot. METHODS: A preliminary study merging the Total3Dgait protocol and the conventional Vicon® Plug-in-Gait marker-sets on five patients with foot deformity was performed to compare the output exactly over the same gait cycles. In the second study, 15 patients with equinus varus foot were assessed retrospectively by means of the Total3Dgait protocol before and after surgery. Data on ankle kinematics were compared to those of a control group. The Functional Ambulation Categories scale and other goals such as orthosis/aids removal, decrease in foot pain, healing of calluses and sores were considered as measures of clinical outcome. FINDINGS: The Total3Dgait protocol provides additional joint motion, in the coronal and transverse planes. Kinematics in the three anatomical planes improved significantly although no changes in time-distance parameters were evident. Improvement in clinical outcome measures was also achieved. INTERPRETATION: The new protocol provides valuable additional data in measuring full three dimensional kinematics of the foot during gait. Whereas the speed of walking was unchanged after surgery for most of patients, the kinematic changes in the three anatomical planes, as measured by the new protocol, were the only measures able to demonstrate motion changes induced by surgery at the foot and to explain subject-specific gains as improvement in stability during walking, relief of pain, calluses and sores, and removal or modification of foot orthosis and aids.

Leardini A, Benedetti MG, Berti L, Bettinelli D, Nativo R, Giannini S.(2007)   “Rear-foot, mid-foot and fore-foot motion during the stance phase of gait.” Gait & Posture. 2007 Mar;25(3):453-62. This paper proposes a new protocol designed to track a large number of foot segments during the stance phase of gait with the smallest possible number of markers, with particular clinical focus on coronal plane alignment of the rear-foot, transverse and sagittal plane alignment of the metatarsal bones, and changes at the medial longitudinal arch. The shank, calcaneus, mid-foot and metatarsus were assumed to be 3D rigid bodies. The longitudinal axis of the first, second and fifth metatarsal bones and the proximal phalanx of the hallux were also tracked independently. Skin markers were mounted on bony prominences or joint lines, avoiding the course of main tendons. Trajectories of the 14 markers were collected by an eight-camera motion capture system at 100 Hz on a population of 10 young volunteers. Three-dimensional joint rotations and planar angles were calculated according to anatomically based reference frames. The marker set was well visible throughout the stance phase of gait, even in a camera configuration typical of gait analysis of the full body. The time-histories of the joint rotations and planar angles were well repeatable among subjects and consistent with clinical and biomechanical knowledge. Several dynamic measurements were originally taken, such as elevation/drop of the medial longitudinal arch and of three metatarsal bones, rear-foot to fore-foot rotation and transverse plane deformation of the metatarsus. The information obtained from this protocol, consistent with previous clinical knowledge, enhanced our understanding of the dynamics of the human foot during stance.

Back to Top

Takabayashi T, Edama M, Nakamura E, Yokoyama E, Kanaya C and Kubo M (2017 Coordination among the rearfoot, midfoot, and forefoot during walking. Journal of Foot and Ankle Research 10:42 Background: Examining coordination between segments is essential for prevention and treatment of injuries. However, traditional methods such as ratio, cross-correlation technique, and angle-time plot may not provide a complete understanding of intersegmental coordination. The present study aimed to quantify the coordination among the rearfoot, midfoot, and forefoot segments during walking. Methods: Twenty healthy young men walked barefoot on a treadmill. Reflective markers were fixed to their right shank and foot based on the Leardini foot model. Three-dimensional joint angles were calculated at the distal segment, and were expressed relative to the adjacent proximal segment. The coupling angle representing intersegmental coordination was calculated by using the modified vector coding technique, and categorized into the following four coordination patterns: in-phase with proximal dominancy, in-phase with distal dominancy, tanti-phase with proximal dominancy, and anti-phase with distal dominancy. Results:' The results showed that the midfoot was dominantly everted compared with the rearfoot and forefoot during the early stance (i.e., the rearfoot-midfoot coordination and midfoot-forefoot coordination were mainly in-phase with distal and proximal dominancy, respectively). Conclusion: This result may suggest that the midfoot plays a more significant role than the rearfoot and forefoot during early stance. The results of the present study can help in understanding the interaction of the intersegmental foot kinematic time series during walking. The results could be used as data to distinguish the presence of injuries or abnormal inter-segmental foot motions such as pes planus. Additionally, these data might be used in the future in a comparison with data on foot deformities.

Monaghan GM, Lewis CL, Hsu WH, Saltzman E, Hamill J, Holt KG.(2012)   “Forefoot angle determines duration and amplitude of pronation during walking.” Gait & Posture. 2013 May;38(1):8-13 The biomechanical mechanisms that link foot structure to injuries of the musculoskeletal system during gait are not well understood. This study had two parts. The purpose of part one was to determine the relation between clinical rearfoot and forefoot angles and foot angles as they make contact with the ground. The purpose of part two was to determine the effects of large vs. moderate values of both forefoot and rearfoot inversion angles at foot contact on foot kinematics. Clinical foot angle, the relationship between the foot and an axis extrinsically defined relative to the ground, was calculated from digital photographs taken in a prone position. During three speeds of over-ground walking, we measured frontal plane rearfoot and forefoot angle relative to the ground at foot contact, and the following stance phase kinematic measures: amplitude of rearfoot and forefoot eversion, duration of rearfoot and forefoot eversion, and duration between heel-off and onset of rearfoot and forefoot inversion. We found that the clinical forefoot angle predicted the forefoot angle at foot contact. Individuals with a large inversion forefoot angle at contact also had greater amplitude of forefoot eversion and everted longer during stance. We discuss the possible mechanisms for the increased risk of injury to the hip reported for individuals that have a large clinical forefoot angle in non-weight bearing. Equally important is the finding that rearfoot angle at contact did not predict the motions of the rearfoot or forefoot during stance.

Lin SC, Chen CP, Tang SF, Wong AM, Hsieh JH, Chen WP.(2013)   “Changes in windlass effect in response to different shoe and insole designs during walking.” Gait & Posture. 2013 Feb;37(2):235-41. Windlass effect occurs during the pre-swing phase of gait cycle in which the peak tensile strain and force of the plantar aponeurosis (PA) is reached. The increased dorsiflexion angle of the 1st metatarsophalangeal (MTP) joint is the main causing factor. The aim of this study was to investigate thoroughly in finding the appropriate shoe and insole combination that can effectively decrease the windlass effect. Foot kinematic analyses of 10 normal volunteers (aged 25.2±2.1 years, height of 167.4±9.1 cm, and weight of 66.2±18.1 kg) were performed during gait under the conditions of barefoot, standard shoe (SS) with flat insole (FI) or carbon fiber insole (CFI), and rocker sole shoe (RSS) with FI or CFI. The shoe cover consisting of transparent polymer was used for accurate measurement of kinematic data as specific areas on the cover can be cut away for direct placement of reflective markers onto the skin. Under barefoot condition, the mean of maximum dorsiflexion angle of the 1st MTP joint was measured to be 48.0±7.3°, and decreased significantly to 28.2±5.7° when wearing SS with FI, and 24.1±5.7° when wearing SS with CFI. This angle was further decreased to around 13° when wearing RSS with FI or CFI. Subjects wearing footwear alone can increase the minimum medial longitudinal angle and decrease the maximum plantarflexion angle of metatarsus related to the calcaneus as compared with barefoot condition, resulting in flatter medial foot arch. Results suggested that RSS is the effective footwear in reducing the windlass effect regardless the type of insole inserted. The findings in this study provided us with the evidences in finding the appropriate footwear for treating foot disorders such as plantar fasciitis by effectively reducing the windlass effect.

Caravaggi P, Leardini A, Crompton R.(2010)   “Kinematic correlates of walking cadence in the foot.” J Biomech. 2010 Aug 26;43(12):2425-33. Evidence has frequently been reported of modifications in gait patterns within the lower limb related to the cadence of walking. Most reports have concerned relationships between cadence and kinematic and the kinetic changes occurring in the main joints and muscles of the lower limb as a whole. The aim of the present study was to assess whether significant changes are also measurable in kinematics of the foot segments. An existing 15 marker-set protocol allowed a four-segment foot and shank model to be defined for relative rotations between the segments to be calculated. Stereophotogrammetry was employed to record marker position data from ten subjects walking at three cadences. The slow- and normal cadence datasets showed similar profiles of joint rotation in three anatomical planes, but significant differences were found between these and the fast cadence. At all joints, frame-by-frame statistical analysis revealed increased dorsiflexion from heel-strike to midstance (p < 0.05) and increased plantarflexion from midstance to toe-off (p < 0.05) with increasing cadence. From foot-flat to heel-rise, the fast cadence kinematic data showed a decreased range of motion in the sagittal-plane between forefoot and rearfoot (3.2 degrees +/- 1.2 degrees at slow cadence; 2.0 degrees +/- 0.8 degrees at fast cadence; p < 0.05). The cadences imposed and the multisegment protocol revealed significant kinematic changes in the joints of the foot during barefoot walking.

Back to Top

Sinclair J, Taylor PJ, Hebron J, Chockalingam N(2014) Differences in multi-segment foot kinematics measured using skin and shoe mounted markers. The Foot and Ankle Online Journal 7 (2): 7 Models with three segments have been implemented in order to represent the movement of the foot in a comprehensive way during walking and running, however the efficacy of mounting such a system of markers externally onto the shoe has not been explored. The aim of the current investigation was to determine whether 3-D three-segment foot kinematics differ between skin and shoe-mounted markers. Twelve male participants walked and ran at 1.25m/s and 4.0m/s along a 22 m runway. Multi-segment foot kinematics were captured simultaneously using markers placed externally on the shoe and on the skin through windows cut in the shoe. Wilcoxon tests were used to compare the 3-D kinematic parameters, and coefficients of multiple correlations (CMC) were employed to contrast the 3-D kinematic waveforms. Strong correlations were observed between the calcaneus-tibia waveforms R2 ≥0.957. However, at the more distal foot articulations lower correlations were found midfoot-calcaneus R2 ≥0.484, metatarsus-midfoot R2 ≥0.538 and metatarsus-calcaneus R2 ≥0.335. Significant differences between in discrete kinematic parameters were also observed between skin and shoe mounted markers, at the midfoot-calcaneus, forefoot-midfoot and forefoot-calcaneus articulations. The results indicate that shoe mounted markers do not fully represent true foot movement, and should therefore be interpreted with caution during examination of multiple-segment foot kinematics. Back to Top

Davis RB, Ounpuu S, Tyburski D, Gage JR. (1991) A Gait Analysis Data Collection and Reduction Technique. Human Movement Science 10: 575-587. The clinical objective of the gait analysis laboratory, developed by United Technologies Corporation (Hartford, CT, USA) in 1980, at the Newington Children's Hospital is to provide quantified assessments of human locomotion which assist in the orthopaedic management of various pediatric gait pathologies. The motion measurement system utilizes a video-based data collection strategy similar to commercially available systems for motion data collection. Anatomically aligned, passive, retroreflective markers placed on the subject are illuminated, detected, and stored in dedicated camera hardware while data are acquired from force platforms and EMG transducers. Three-dimensional marker position information is used to determine: (i) the orientation of segmentally-embedded coordinate systems, (ii) instantaneous joint center locations, and (iii) joint angles. Joint kinetics, i.e., moments and powers, may also be computed if valid force plate data are collected.

Kadaba MP, Ramakrishnan HK, Wootten ME (1990) Measurement of Lower Extremity Kinematics During Level Walking. J. Orthopedic Research 8: 383-392. A simple external marker system and algorithms for computing lower extremity joint angle motion during level walking were developed and implemented on a computer-aided video motion analysis system (VICON). The concept of embedded axes and Euler rotation angles was used to define the three-dimensional joint angle motion based on a set of body surface markers. Gait analysis was performed on 40 normal young adults three times on three different test days at least 1 week apart using the marker system. Angular motion of the hip, knee, and ankle joints and of the pelvis were obtained throughout a gait cycle utilizing the three-dimensional trajectories of markers. The effect of uncertainties in defining the embedded axis on joint angles was demonstrated using sensitivity analysis. The errors in the estimation of joint angle motion were quantified with respect to the degree of error in the construction of embedded axes. The limitations of the model and the marker system in evaluating pathologic gait are discussed. The relatively small number of body surface markers used in the system render it easy to implement for use in routine clinical gait evaluations. Additionally, data presented in this paper should be a useful reference for describing and comparing pathologic gait patterns.

Bell AL, Pederson DR, and Brand RA (1989) Prediction of hip joint center location from external landmarks. Human Movement Science. 8:3-16 The approaches to predicting the hip joint centre (HJC) location of Tylkowski's group and Andriacchi's group were evaluated for accuracy and validity in children and adults of both sexes. Using Tylkowski's approach, we found that the three-dimensional (3-D) HJC location in adults (expressed as a percentage of the distance between the anterior superior iliac spines (ASIS)) was 30% distal, 14% medial, and 22% posterior to the ASIS, and predicted the HJC location to within 3.3 cm of the true location with 95% certainty. Using Andriacchi's approach, we found that the HJC was located in the frontal plane distal and lateral to the midpoint of a line between the ASIS and pubic symphysis, and varied from 2.2 cm distal and 0.78 cm lateral in girls to 4.6 cm distal and 1.7 cm lateral in men. A more accurate method of estimating the 3-D HJC location combined a modification of Andriacchi's approach (estimating frontal plane location of HJC) with a modification of Tylkowski's approach (estimating HJC location posterior to a frontal plane), and could predict the HJC location in adults to within 2.6 cm of the true location with 95% certainty.

Bell AL, Pedersen DR, Brand RA (1990) A Comparison of the Accuracy of Several hip Center Location Prediction Methods. J Biomech. 23, 617-621. Back to Top

Morgan KD, Noehren B (2018) Identification of knee gait waveform pattern alterations in individuals with patellofemoral pain using fast Fourier transform PLoS ONE 13(12):e0209015 Abstract: Patellofemoral pain (PFP) is one of the most common overuse injuries of the knee. Previous research has found that individuals with PFP exhibit differences in peak hip kinematics; however, differences in peak knee kinematics, where the pain originates, are difficult to elucidate. To better understand the mechanism behind PFP, we sought to characterize differences in knee gait kinematic waveform patterns in individuals with PFP compared to healthy individuals using fast Fourier transform (FFT). Sixteen control and sixteen individuals with PFP participated in a fast walk protocol. FFT was used to decompose the sagittal, frontal and transverse plane knee gait waveforms into sinusoidal signals. A two-way ANOVA and Bonferroni post hoc analysis compared group, limb and interaction effects on sagittal, frontal and transverse amplitude, frequency and phase components between control and PFP individuals gait waveforms. Differences in frequency and phase values were found in the sagittal and frontal plane knee waveforms between the control and PFP groups. The signal-to-noise ratio also reported significant differences between the PFP and control limbs in the sagittal (p<0.01) and frontal planes (p = 0.04). The findings indicate that differences in gait patterns in the individuals with PFP were not the result of amplitude differences, but differences attributed to temporal changes in gait patterns detected by the frequency and phase metrics. These changes suggest that individuals with PFP adopted a more deliberate, stiffer gait and exhibit altered joint coordination. And the FFT technique could serve as a fast, quantifiable tool for clinicians to detect PFP.

Merican AM, Amis AA (2009) Iliotibial band tension affects patellofemoral and tibiofemoral kinematics Journal of Biomechanics Volume 42, Issue 10, 22 July 2009, Pages 1539-1546 The iliotibial band (ITB) has an important role in knee mechanics and tightness can cause patellofemoral maltracking. This study investigated the effects of increasing ITB tension on knee kinematics. Nine fresh-frozen cadaveric knees had the components of the quadriceps loaded with 175 N. A Polaris optical tracking system was used to acquire joint kinematics during extension from 100° to 0° flexion. This was repeated after the following ITB loads: 30, 60 and 90 N. There was no change with 30 N load for patellar translation. On average, at 60 and 90 N, the patella translated laterally by 0.8 and 1.4 mm in the mid flexion range compared to the ITB unloaded condition. The patella became more laterally tilted with increasing ITB loads by 0.7°, 1.2° and 1.5° for 30, 60 and 90 N, respectively. There were comparable increases in patellar lateral rotation (distal patella moves laterally) towards the end of the flexion cycle. Increased external rotation of the tibia occurred from early flexion onwards and was maximal between 60° and 75° flexion. The increase was 5.2°, 9.5° and 13° in this range for 30, 60 and 90 N, respectively. Increased tibial abduction with ITB loads was not observed. The combination of increased patellar lateral translation and tilt suggests increased lateral cartilage pressure. Additionally, the increased tibial external rotation would increase the Q angle. The clinical consequences and their relationship to lateral retinacular releases may be examined, now that the effects of a tight ITB are known.

Back to Top

Tucker CA, Bagley A, Wesdock K, Church C, Henley J, Masiello G   ”Kinematic Modeling of the Shoulder Complex in Tetraplegia“2008 - Topics in Spinal Cord Injury Rehabilitation, Volume 13, Number 4 Spring 2008 - Contemporary Perspectives of Upper Limb Management In comparison to other joints in the human body, the shoulder complex is particularly reliant on the coordination of active muscle forces to generate both movement and stability during activities using the upper extremities. The resultant imbalance of muscle forces across the shoulder, coupled with the increased reliance on the shoulder for functional mobility, puts the individual with tetraplegia at great risk for developing shoulder pathology. The ability to quantify the movement of the shoulder, and in particular the sequence of shoulder complex movement components within functional tasks, can provide information to better inform clinical and surgical decision making. In this article, we will discuss the impact of tetraplegia on shoulder biomechanics and function, provide an overview of general principles and current status of kinematic modeling of the shoulder complex, and describe emerging applications of quantitative motion analysis of the shoulder complex.

Hidler J, Wisman W, Neckel N   ”Kinematic trajectories while walking within the Lokomat robotic gait-orthosis“ 2008 - Clinical Biomechanics 23 (2008) 1251-1259 Background One of the most popular robot assisted rehabilitation devices used is the Lokomat. Unfortunately, not much is known about the behaviors exhibited by subjects in this device. The goal of this study was to evaluate the kinematic patterns of individuals walking inside the Lokomat compared to those demonstrated on a treadmill. Methods Six healthy subjects walked on a treadmill and inside the Lokomat while the motions of the subject and Lokomat were tracked. Joint angles and linear motion were determined for Lokomat and treadmill walking. We also evaluated the variability of the patterns, and the repeatability of measuring techniques. Findings The overall kinematics in the Lokomat are similar to those on a treadmill, however there was significantly more hip and ankle extension, and greater hip and ankle range of motion in the Lokomat (P < 0.05). Additionally, the linear movement of joints was reduced in the Lokomat. Subjects tested on repeated sessions presented consistent kinematics, demonstrating the ability to consistently setup and test subjects. Interpretation The reduced degrees of freedom in the Lokomat are believed to be the reason for the specific kinematic differences. We found that despite being firmly attached to the device there was still subject movement relative to the Lokomat. This led to variability in the patterns, where subjects altered their gait pattern from step to step. These results are clinically important as a variable step pattern has been shown to be a more effective gait training strategy than one which forces the same kinematic pattern in successive steps.

Goulermas JY, Howard D, Nester CJ, Jones RE, Ren L   ”Regression Techniques for the Prediction of Lower Limb Kinematics.“ 2005 - Journal of Biomechanical Engineering, Volume 127, Issue 6, pp. 1020-1024

Siegel KL, Kepple TM, Caldwell GE   ”Improved agreement of foot segmental power and rate of energy change during gait: Inclusion of distal power terms and use of three-dimensional models.“ 1996 - Journal of Biomechanics 29(6):823-827 Traditional models used to calculate foot segmental power have yielded poor agreement between foot power and the rate of energy change during the stance phase of gait and limited the applicability of foot segmental power analyses to swing phase only. The purpose of this study was to improve the agreement of foot segemental power and rate of energy change by using more inclusive models to calculate foot segmental power and energy. The gait of 15 adult subjects was studied and models were used to calculate foot segmental power that included either the proximal terms only (Model P, the most common method in the literature) or both proximal and distal terms (Model PD, a mathematically complete model). Power and energy terms were computed in to ways, from sagittal plane vector components only (two-dimensional condition) and from complete three-dimensional components (three-dimensional condition). Results revealed that the more inclusive the model, the higher the agreement of foot power and rate of energy change. During stance phase, Model P produced poor agreement (rc = 0.108) for both two-dimensional and three-dimensional conditions, Model PD-2D yielded higher agreement (rc = 0.645), and Model PD-3D exhibited nearly perfect agreement (rc = 0.956). The advantages of a segmental power analysis include the ability to identify the mechanisms of energy transfer into and out of the foot during movement. The results of this study suggest that foot power analyses are valid when using Model PD-3D to describe foot function during locomotion.

Buczek FL, Kepple TM, Lohmann Siegel K., Stanhope SJ   ”Effect of one, three, and six degree-of-freedom modeling upon joint powers at the normal knee.“ 1994 - Proceedings of the Second World Congress on Biomechanics, 151

Buczek F., Siegel K., Kepple T., Stanhope S.   ”Ground reaction force signal processing in joint power calculations.“ 1991 - Proceedings of the Seventh Annual East Coast Gait Laboratory Conference

Back to Top

Verheul, J, Gregson, W, Lisboa, P, Vanrenterghem, J and Robinson, MA (2018) Whole-body biomechanical load in running-based sports: the validity of estimating ground reaction forces from segmental. Journal of Science and Medicine in Sport. ISSN 1440-2440 Objective: Unlike physiological loads, the biomechanical loads of training in running-based sports are still largely unexplored. This study, therefore, aimed to assess the validity of estimating ground reaction forces (GRF), as a measure of external whole-body biomechanical loading, from segmental accelerations. Methods: Fifteen team-sport athletes performed accelerations, decelerations, 90° cuts and straight running at different speeds including sprinting. Full-body kinematics and GRF were recorded with a three-dimensional motion capture system and a single force platform respectively. GRF profiles were estimated as the sum of the product of all fifteen segmental masses and accelerations, or a reduced number of segments. Results: Errors for GRF profiles estimated from fifteen segmental accelerations were low (1-2 Nkg−1) for low-speed running, moderate (2-3 Nkg−1) for accelerations, 90° cuts and moderate-speed running, but very high (>4 Nkg−1) for decelerations and high-speed running. Similarly, impulse (2.3-11.1%), impact peak (9.2-28.5%) and loading rate (20.1-42.8%) errors varied across tasks. Moreover, mean errors increased from 3.26 ± 1.72 Nkg−1 to 6.76 ± 3.62 Nkg−1 across tasks when the number of segments was reduced. Conclusions: Accuracy of estimated GRF profiles and loading characteristics was dependent on task, and errors substantially increased when the number of segments was reduced. Using a direct mechanical approach to estimate GRF from segmental accelerations is thus unlikely to be a valid method to assess whole-body biomechanical loading across different dynamic and high-intensity activities. Researchers and practitioners should, therefore, be very cautious when interpreting accelerations from one or several segments, as these are unlikely to accurately represent external whole-body biomechanical loads.

Tomescu SS, Bakker R Beach TAC, Chandrashekar N The Effects of Filter Cutoff Frequency on Musculoskeletal Simulations of High-Impact Movements. Journal of Applied Biomechanics, 2018, 34, 336-341 ref Estimation of muscle forces through musculoskeletal simulation is important in understanding human movement and injury. Unmatched filter frequencies used to low-pass filter marker and force platform data can create artifacts during inverse dynamics analysis, but their effects on muscle force calculations are unknown. The objective of this study was to determine the effects of filter cutoff frequency on simulation parameters and magnitudes of lower-extremity muscle and resultant joint contact forces during a high-impact maneuver. Eight participants performed a single-leg jump landing. Kinematics was captured with a 3D motion capture system, and ground reaction forces were recorded with a force platform. The marker and force platform data were filtered using 2 matched filter frequencies (10–10 Hz and 15–15 Hz) and 2 unmatched filter frequencies (10–50 Hz and 15–50 Hz). Musculoskeletal simulations using computed muscle control were performed in OpenSim. The results revealed significantly higher peak quadriceps (13%), hamstrings (48%), and gastrocnemius forces (69%) in the unmatched (10–50 Hz and 15–50 Hz) conditions than in the matched (10–10 Hz and 15–15 Hz) conditions (P < .05). Resultant joint contact forces and reserve (nonphysiologic) moments were similarly larger in the unmatched filter categories (P < .05). This study demonstrated that artifacts created from filtering with unmatched filter cutoffs result in altered muscle forces and dynamics that are not physiologic.

Ross, G., Dowling, B., Graham, R., Troje, N. F., Fischer, S. L., Graham, R. B. (2018)   ”Objectively differentiating whole-body movement patterns between elite and novice athletes.“ Medicine & Science in Sports & Exercise Introduction: Movement screens are frequently used to identify abnormal movement patterns that may increase risk of injury or hinder performance. Abnormal patterns are often detected visually based on the observations of a coach or clinician. Quantitative, or data-driven methods can increase objectivity, remove issues related to inter-rater reliability and offer the potential to detect new and important features that may not be observable by the human eye. Applying principal components analysis (PCA) to whole-body motion data may provide an objective data-driven method to identify unique and statistically important movement patterns, an important first step to objectively characterize optimal patterns or identify abnormalities. Therefore, the primary purpose of this study was to determine if PCA could detect meaningful differences in athletes’ movement patterns when performing a non-sport-specific movement screen. As a proof of concept, athlete skill level was selected a priori as a factor likely to affect movement performance. Methods: Motion capture data from 542 athletes performing seven dynamic screening movements (i.e. bird-dog, drop jump, T-balance, step-down, L-hop, hop-down, and lunge) were analyzed. A PCA-based pattern recognition technique and linear discriminant analysis with cross-validation were used to determine if skill level could be predicted objectively using whole-body motion data. Copyright © 2018 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Results: Depending on the movement, the validated linear discriminate analysis models accurately classified 70.66-82.91% of athletes as either elite or novice. Conclusion: We have provided proof that an objective data-driven method can detect meaningful movement pattern differences during a movement screening battery based on a binary classifier (i.e. skill level in this case). Improving this method can enhance screening, assessment and rehabilitation in sport, ergonomics and medicine.

Whatling GM, Evans SL, Holt CA.   ”Comparing different data collection and analysis techniques for quantifying healthy knee joint function during stair ascent and descent.“ 2009 - Proc. IMechE Vol. 223 Part H: J. Engineering in Medicine:981-990. Abstract: There is currently no standard data collection or analysis method for the assessment of stair gait using motion analysis. This makes the comparison of results from different studies difficult. It is important to gain an appreciation of the discrepancies in kinematic and kinetic information generated by employing different computational approaches, as these differences may be critical in cases where methodologies were to change over a long-term study. This study explores the effect of using different methodologies for the assessment of non-pathological knee function of ten subjects during stair ascent and descent. Two methods of computing knee kinematics were compared: (a) using in-house software and a pointer method of anatomical calibration and (b) using commercial software, Visual3D (C-Motion, Inc.) and skin-mounted markers. Significant differences were found between the two methods when calculating a frontal plane range of motion (p,0.05). Three methods of computing knee moments were compared. Knee moments computed using the inverse dynamic analysis (IDA) approach of Visual3D (C-motion, Inc.) were significantly different (p,0.05) to those calculated using in-house IDA software that ignores the foot and ankle and to those computed using a vector cross-product approach. This study highlights the implications of comparing data generated from different collection and analysis methods. pdf

Richards J, Thewlis D, Selfe J, Cunningham A, Hayes C.   ”A biomechanical investigation of a single-limb squat: implications for lower extremity rehabilitation exercise.“ 2008 - J Athl Train. 2008 Sep-Oct;43(5):477-82. :Abstract CONTEXT: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. OBJECTIVE: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60 degrees of knee flexion while performing a single-limb squat at different decline angles.DESIGN: Participants acted as their own controls in a repeated-measures design.PATIENTS OR OTHER PARTICIPANTS: We recruited 10 participants who had no pain, injury, or neurologic disorder.INTERVENTION(S): Participants performed single-limb squats at different decline angles. MAIN OUTCOME MEASURE(S): Angle-specific knee and ankle moments were calculated at 60 degrees of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60 degrees of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. RESULTS: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P = .001), but EMG activity in the gastrocnemius increased between 16 degrees and 24 degrees (P = .018). CONCLUSIONS: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24 degrees decline angle compared with the 16 degrees decline angle. This indicates that decline squats at an angle greater than 16 degrees may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee. [PMID: 18833310 Reference]

Orishimo KF, Kremenic IJ, Pappas E, Hagins M, Liederbach M.   ”Comparison of landing biomechanics between male and female professional dancers.“ 2009 - Am J Sports Med. 2009 Nov;37(11):2187-93. Epub 2009 Jun 26. BACKGROUND: The incidence of anterior cruciate ligament injuries among dancers is much lower than that among team sport athletes and no clear gender disparity has been reported in the dance population. Although numerous studies have observed differences in lower extremity landing biomechanics between male and female athletes, there is currently little research examining the landing biomechanics of male and female dancers. Comparing landing biomechanics within this population may help explain the lower overall anterior cruciate ligament injury rates and the lack of gender disparity. HYPOTHESIS: Due to the fact that dancers receive jump-specific and balance-specific training from a very young age, we hypothesized that there would be no gender differences in drop-landing biomechanics in professional dancers. STUDY DESIGN: Controlled laboratory study. METHODS: Kinematics and ground-reaction forces were recorded as 33 professional modern and ballet dancers (12 men and 21 women) performed single-legged drop landings from a 30-cm platform. Joint kinematics and kinetics were compared between genders. RESULTS: No gender differences in joint kinematics or kinetics were found during landings (multivariate analysis of variance: P = .490 and P = .175, respectively). A significant relationship was found between the age at which the dancers began training and the peak hip adduction angle during landing (r = .358, P = .041). CONCLUSION: In executing a 30-cm drop landing, male and female dancers exhibited similar landing strategies and avoided landing patterns previously associated with increased injury rates. CLINICAL RELEVANCE: Commonly reported biomechanical differences between men and women, as well as the gender disparity among athletes in the incidence of ACL injuries, may be the result of inadequate experience in proper balance and landing technique rather than intrinsic gender factors. Beginning jump-specific and balance-specific training at an early age may counteract the potentially harmful adaptations in landing biomechanics observed in female athletes after maturity.

Bruening DA, Crewe AN, Buczek FL   ”A simple, anatomically based correction to the conventional ankle joint center“ 2008 - Clinical Biomechanics 23(10):1299-1302 Background. Conventional motion analysis studies define the ankle joint center as the midpoint between the most medial and lateral aspects of the malleoli, yet research points toward a more distal joint center location. The purpose of this study was to develop and evaluate an anatomically based correction that would move the conventional ankle joint center to a more accurate location. Methods. Lower extremity radiographs from 30 pediatric patients were analyzed retrospectively. An offset between the conventional and more accurate ankle joint centers was measured and correlated to other common anatomical measures based on conventional skin mounted marker positions. The best correlated measure was used to define a simple correction factor, which was subsequently evaluated by its effect on six degree-of-freedom ankle joint translations during normal gait (n = 8). Findings. Shank length was found to have the highest bivariate linear correlation (r = 0.89) with the offset. Adjusting the ankle joint center using a percentage of shank length (2.7%) was also as accurate as the regression equation in predicting offset (mean error 0.6 mm, or 6% offset). Adjusting the ankle joint center using this simple percentage resulted in a 25% reduction in mean ankle joint translations during normal gait. Interpretation. The accuracy of the ankle joint center can be increased through a simple, anatomically based correction. This correction may prove beneficial in some kinematic and kinetic applications requiring increased anatomical fidelity. [PMID: 18848739 Reference]

Keefer M, King J, Powell D, Krusenklaus JH, Zhang S   ”Effects of modified short-leg walkers on ground reaction force characteristics.“ 2008 - Keefer, M, King, J, Powell, D, Krusenklaus, JH, Zhang, S. Effects of modified short-leg walkers on ground reaction force characteristics. Clin Biomech (Bristol, Avon). 2008; 23(9):1172-7. BACKGROUND: Although short-leg walkers are often used in the treatment of lower extremity injuries (ankle and foot fractures and severe ankle sprains), little is known about the effect the short-leg walker on gait characteristics. The purpose was to examine how heel height modifications in different short-leg walkers and shoe side may affect ground reaction forces in walking. METHODS: Force platforms were used to collect ground reaction force data on 10 healthy participants. Five trials were performed in each of six conditions: lab shoes, gait walker, gait walker with heel insert on shoe side, gait walker modified with insert on walker side, equalizer walker, and equalizer walker with heel insert on shoe side. Conditions were randomized and walking speed was standardized between conditions. A 2×6 (sidexcondition) repeated analysis of variance was used on selected ground reaction force variables (P<0.05). FINDINGS: The application of a walker created peak vertical and anteroposterior ground reaction forces prior to the normal peaks associated with the loading response. Wearing a walker introduced an elevated minimum vertical ground reaction force in all conditions except the equalizer walker when compared to shoe on the shoe side. Peak propulsive anteroposterior ground reaction forces were smaller in all walker conditions compared to shoe on walker side. INTERPRETATION: The application of heel insert in gait walker with heel insert (on shoe side) and gait walker modified (on walker side) does not diminish the minimum vertical ground reaction force as hypothesized. Wearing a walker decreases the peak propulsive anteroposterior ground reaction force on the walker side and induces asymmetrical loading. Reference

Zhang, S, Clowers, KG, Powell, D.   ”Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers“ 2006 - Zhang, S, Clowers, KG, Powell, D. Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers. Gait & Posture. 2006; 24(4):487-92. Short-leg walking boots offer several advantages over traditional casts. However, their effects on ground reaction forces (GRF) and three-dimensional (3D) biomechanics are not fully understood. The purpose of the study was to examine 3D lower extremity kinematics and joint dynamics during walking in two different short-leg walking boots. Eleven (five females and six males) healthy subjects performed five level walking trials in each of three conditions: two testing boot conditions, Gait Walker (DeRoyal Industries, Inc.) and Equalizer (Royce Medical Co.), and one pair of laboratory shoes (Noveto, Adidas). A force platform and a 6-camera Vicon motion analysis system were used to collect GRFs and 3D kinematic data during the testing session. A one-way repeated measures analysis of variance (ANOVA) was used to evaluate selected kinematic, GRF, and joint kinetic variables (p<0.05). The results revealed that both short-leg walking boots were effective in minimizing ankle eversion and hip adduction. Neither walker increased the bimodal vertical GRF peaks typically observed in normal walking. However, they did impose a small initial peak (<1BW) earlier in the stance phase. The Gait Walker also exhibited a slightly increased vertical GRF during midstance. These characteristics may be related to the sole materials/design, the restriction of ankle movements, and/or the elevated heel heights of the tested walkers. Both walkers appeared to increase the demand on the knee extensors while they decreased the demand of the knee and hip abductors based on the joint kinetic results. Reference

Cereatti A, Della Croce U, Cappozzo A   ”Reconstruction of skeletal movement using skin markers: Comparative assessment of bone pose estimators.“ 2006 - Journal of NeuroEngineering and Rehabilitation, 3:7 Reference

Cappello, A., Cappozzo, A., La Palombara, P.F., Lucchetti, L., Leardini, A.   ”Multiple anatomical landmark calibration for optimal bone pose estimation.“ 1997 - Human Movement Science. 16: 259-274

Siegel KL, Kepple TM, Caldwell GE   ”Improved agreement of foot segmental power and rate of energy change during gait: Inclusion of distal power terms and use of three-dimensional models.“ 1996 - Journal of Biomechanics 29(6):823-827 Traditional models used to calculate foot segmental power have yielded poor agreement between foot power and the rate of energy change during the stance phase of gait and limited the applicability of foot segmental power analyses to swing phase only. The purpose of this study was to improve the agreement of foot segemental power and rate of energy change by using more inclusive models to calculate foot segmental power and energy. The gait of 15 adult subjects was studied and models were used to calculate foot segmental power that included either the proximal terms only (Model P, the most common method in the literature) or both proximal and distal terms (Model PD, a mathematically complete model). Power and energy terms were computed in to ways, from sagittal plane vector components only (two-dimensional condition) and from complete three-dimensional components (three-dimensional condition). Results revealed that the more inclusive the model, the higher the agreement of foot power and rate of energy change. During stance phase, Model P produced poor agreement (rc = 0.108) for both two-dimensional and three-dimensional conditions, Model PD-2D yielded higher agreement (rc = 0.645), and Model PD-3D exhibited nearly perfect agreement (rc = 0.956). The advantages of a segmental power analysis include the ability to identify the mechanisms of energy transfer into and out of the foot during movement. The results of this study suggest that foot power analyses are valid when using Model PD-3D to describe foot function during locomotion.

Siegel KL, Kepple TM, O'Connell PO, Gerber LH, Stanhope SJ   ”Evaluation of foot function during the stance phase of gait.“ 1995 - Foot & Ankle International 16(12):764-770

Kepple TM, Arnold AS, Stanhope SJ, Siegel KL   ”Measurement of musculoskeletal motion from surface landmarks: A three-dimensional computer graphics approach.“ 1994 - Journal of Biomechanics 27(3):365-371

Buczek FL, Kepple TM, Siegel KL, Stanhope SJ.   ”Translational and Rotational Joint Power Terms in a Six Degree-of-Freedom Model of the Normal Ankle Complex.“ 1994 - Journal of Biomechanics 27(12):1447-1457

Siegel KL, Stanhope SJ, Caldwell GE   ”Kinematic and kinetic adaptations in the lower limb during stance in gait of unilateral femoral neuropathy patients.“ 1993 - Clinical Biomechanics, 8:147-155

Barr AE, Siegel KL, Danoff JV, McGarvey CL III, Tomasko A, Sable I, Stanhope SJ   ”Biomechanical comparison of the energy storing capabilities of SACH and Carbon Copy II prosthetic feet during the stance phase of gait in a person with below knee amputation.“ 1992 - Physical Therapy 72(5):344-54 In this study, the energy-storing capabilities of solid-ankle cushion heel (SACH) and Carbon Copy II prosthetic feet during the stance phase of gait were compared. A person with a unilateral below-knee amputation served as a component of the instrumentation to test the feet under dynamic loads. Ten trials per foot of bilateral stride at “free” velocity were collected with a video-based, three-dimensional data-acquisition system and two force plates. There were no differences between the prosthetic conditions in step length, single-limb support time, and swing period (analysis of variance) or in double-limb support time, cadence, and velocity (Student's t test). Angular kinematics and moments of the hip and knee were unaffected bilaterally by the type of foot. The progression of the center of pressure under the Carbon Copy II was delayed from 15% to 80% of stance as compared with the SACH foot. The Carbon Copy II showed slower unloading in late stance and a later peak propulsive force than did the SACH foot. The Carbon Copy II performed greater work in both the energy-storage (Carbon Copy II = 2.33 J, SACH = 1.16 J) and energy-return (Carbon Copy II = 1.33 J, SACH = 0.34 J) phases of stance and returned energy with 57% efficiency. Although the energy returned by the Carbon Copy II was clinically insignificant during level walking, these results confirm that it performs as an energy-storing device.

Stanhope SJ, Kepple TM, McGuire DA, Roman NL.   ”A Kinematic-Based Technique for Event Time Determination During Gait.“ 1990 - Medical and Biological Engineering and Computing 28:355-360 Visual3D provides an automated determination of events within motion data. An event is defined as a user defined significant occurrence during data collections. Examples of events are: heel strike, mid- stance, foot off during gait, signals generated by analog device associated with bells, buzzers, lights, potentiometers and foot switches, and events based on kinematic data such as mid-swing or mid- stance.|

Kepple TM, Stanhope SJ, Lohmann (Siegel) KN, Roman NL   ”A video-based technique for measuring ankle-subtalar motion during stance.“ 1990 - Journal of Biomedical Engineering 12(4):273-80

Kepple T., Stanhope S. A   ”A Video based, six degree of freedom approach for analyzing human motion.“ 1989 - Proceedings of the Fifth Annual East Coast Gait Laboratories Conference

Kepple T., Stanhope S., Rich A.   ”The presentation and evaluation of a video based, six degree-of-freedom approach for analyzing human motion“ 1988 - Proceedings of the Annual IEEE Engineering in Medicine and Biology Society

Antonsson EK   ”A three-dimensional kinematic acquisition and intersegmental dynamic analysis system for human motion. “ 1982 - Ph.D dissertation, Massachusetts Institute of Technology. NOTE: This was the seminal work that started Tom Kepple on the path of MOVE3D.

Back to Top

Robinson MA, Barton GJ, Lees A, Sett P. (2010)   ”Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer.“ Spinal Cord. 2010 Aug;48(8):619-27 STUDY DESIGN: Cross-sectional study. OBJECTIVES: To quantify three-dimensional (3D) reachable workspace in different groups of tetraplegic participants and to assess their reaching performance within this workspace. SETTING: Northwest Regional Spinal Injuries Centre, UK. METHODS: The 3D reachable workspace of three groups of tetraplegics (NON-OP, operated group (OP) and tetraplegic control group (CON(Tetraplegic)) with varying levels of triceps function together with a healthy control group (CON(Healthy))) was defined by reaching to five target positions (anterior, medial, lateral, superior and inferior) located on the periphery of their workspace. Joint angles and inter-joint co-ordination were analysed after a 3D reconstruction of the thorax, humerus and forearm. The performance related variables of movement time, peak velocity, time-to-peak velocity and curvature index were also examined. RESULTS: The reachable volumes covered were consistent with the level of triceps function as CON(Healthy) covered a significantly greater volume than the tetraplegic groups and in turn the OP covered a larger workspace volume than NON-OP. The reduced workspace of tetraplegics was identified as being due to restrictions in workspace above shoulder height and across the body. Co-ordination data identified some differences in movement patterns but when reaching to targets on the workspace there were no significant differences between the OP and NON-OP groups. CONCLUSION: This study provided a detailed assessment of reachable workspace and target reaching. Tetraplegic participants found the superior and medial parts of the workspace were the most challenging directions. Standardised biomechanical analysis of tetraplegic upper-limb function is required for objective assessment..

Back to Top

Valldecabres R, de Benito AM, Littler G, Richards J. 2018. An exploration of the effect of proprioceptive knee bracing on biomechanics during a badminton lunge to the net, and the implications to injury mechanisms. PeerJ 6:e6033 https://doi.org/10.7717/peerj.6033 The aim of this study was to determine changes in knee biomechanics during badminton lunges due to fatigue, lunge strategy and knee bracing. Kinetic and kinematic data were collected from 16 experienced right-handed badminton players. Three factor repeated measures ANOVAs (lunge direction—fatigue—brace) were performed with Least Significant Difference pairwise comparisons. In addition, clinical assessments including; Y-balance test, one leg hop distance and ankle dorsiflexion range of motion were performed pre- and postfatigue. The knee showed significantly greater flexion during the forehand lunge compared to backhand. In contrast, the internal rotation velocity and the knee extension moment were greater during backhand. Knee angular velocity in the sagittal plane, peak knee moment and range of moment in the coronal plane and stance time showed significantly lower values postfatigue. In addition, the peak knee adduction moment showed significantly lower values in the braced condition in both the fatigued and nonfatigues states, and no significant differences were seen for peak vertical force, loading rate, approach velocity, or in any of the clinical assessment scores. There appears to be greater risk factors when performing a backhand lunge to the net compared to a forehand lunge, and proprioceptive bracing appears to reduce the loading at the knee. Merican AM, Amis AA (2009) Iliotibial band tension affects patellofemoral and tibiofemoral kinematics Journal of Biomechanics Volume 42, Issue 10, 22 July 2009, Pages 1539-1546 The iliotibial band (ITB) has an important role in knee mechanics and tightness can cause patellofemoral maltracking. This study investigated the effects of increasing ITB tension on knee kinematics. Nine fresh-frozen cadaveric knees had the components of the quadriceps loaded with 175 N. A Polaris optical tracking system was used to acquire joint kinematics during extension from 100° to 0° flexion. This was repeated after the following ITB loads: 30, 60 and 90 N. There was no change with 30 N load for patellar translation. On average, at 60 and 90 N, the patella translated laterally by 0.8 and 1.4 mm in the mid flexion range compared to the ITB unloaded condition. The patella became more laterally tilted with increasing ITB loads by 0.7°, 1.2° and 1.5° for 30, 60 and 90 N, respectively. There were comparable increases in patellar lateral rotation (distal patella moves laterally) towards the end of the flexion cycle. Increased external rotation of the tibia occurred from early flexion onwards and was maximal between 60° and 75° flexion. The increase was 5.2°, 9.5° and 13° in this range for 30, 60 and 90 N, respectively. Increased tibial abduction with ITB loads was not observed. The combination of increased patellar lateral translation and tilt suggests increased lateral cartilage pressure. Additionally, the increased tibial external rotation would increase the Q angle. The clinical consequences and their relationship to lateral retinacular releases may be examined, now that the effects of a tight ITB are known. Back to Top

Garg R, Kraszewski AP, Stoecklein HH, Syrkin G, Hillstrom HJ, Backus S, Lenhoff ML, Wolff AL, Crisco JJ, Wolfe SW. (2014) Wrist kinematic coupling and performance during functional tasks: effects of constrained motion. J Hand Surg Am. 2014 Apr;39(4):634-642 PURPOSE: To quantify the coupled motion of the wrist during selected functional tasks and to determine the effects of constraining this coupled motion using a radial-ulnar deviation blocking splint on performance of these tasks. METHODS: Ten healthy, right-handed men performed 15 trials during selected functional tasks with and without a splint, blocking radial and ulnar deviation. The following tasks were performed: dart throwing, hammering, basketball free-throw, overhand baseball and football throwing, clubbing, and pouring. Kinematic coupling parameters (coupling, kinematic path length, flexion-extension range of motion, radial-ulnar deviation range of motion, flexion-extension offset, and radial-ulnar deviation offset) and performance were determined for each functional task. A generalized estimation equation model was used to determine whether each kinematic coupling parameter was significantly different across tasks. A repeated-measures generalized estimation equation model was used to test for differences in performance and kinematic coupling parameters between the free and splinted conditions. RESULTS: Wrist motion exhibited linear coupling between flexion-extension and radial-ulnar deviation, demonstrated by R(2) values from 0.70 to 0.99. Average wrist coupling and kinematic path lengths were significantly different among tasks. Coupling means and kinematic path lengths were different between free and splinted conditions across all tasks other than pouring. Performance was different between wrist conditions for dart throwing, hammering, basketball shooting, and pouring. CONCLUSIONS: Wrist kinematic coupling parameters are task specific in healthy individuals. Functional performance is decreased when wrist coupling is constrained by an external splint. CLINICAL RELEVANCE: Surgical procedures that restrict wrist coupling may have a detrimental effect on functional performance as defined in the study. Patients may benefit from surgical reconstructive procedures and wrist rehabilitation protocols designed to restore kinematic coupling. Back to Top

Parel I, Cutti AG, Kraszewski A, Verni G, Hillstrom H, Kontaxis A. (2014) Intra-protocol repeatability and inter-protocol agreement for the analysis of scapulo-humeral coordination. Med Biol Eng Comput. 2014 Mar;52(3):271-82 Multi-center clinical trials incorporating shoulder kinematics are currently uncommon. The absence of repeatability and limits of agreement (LoA) studies between different centers employing different motion analysis protocols has led to a lack dataset compatibility. Therefore, the aim of this work was to determine the repeatability and LoA between two shoulder kinematic protocols. The first one uses a scapula tracker (ST), the International Society of Biomechanics anatomical frames and an optoelectronic measurement system, and the second uses a spine tracker, the INAIL Shoulder and Elbow Outpatient protocol (ISEO) and an inertial and magnetic measurement system. First within-protocol repeatability for each approach was assessed on a group of 23 healthy subjects and compared with the literature. Then, the between-protocol agreement was evaluated. The within-protocol repeatability was similar for the ST ([Formula: see text] = 2.35°, [Formula: see text] = 0.97°, SEM = 2.5°) and ISEO ([Formula: see text] = 2.24°, [Formula: see text] = 0.97°, SEM = 2.3°) protocols and comparable with data from published literature. The between-protocol agreement analysis showed comparable scapula medio-lateral rotation measurements for up to 120° of flexion-extension and up to 100° of scapula plane ab-adduction. Scapula protraction-retraction measurements were in agreement for a smaller range of humeral elevation. The results of this study suggest comparable repeatability for the ST and ISEO protocols and between-protocol agreement for two scapula rotations. Different thresholds for repeatability and LoA may be adapted to suit different clinical hypotheses. Back to Top

Chan ZYSm Zhang JHW, Au IPH, An WW, Shum GLK, Ng GYF, Cheung RTH. (2017).   ”Gait retraining lowers injury risk in novice distance runners: a randomized controlled trial.“ The American Journal of Sports Medicine. Background: With distance running gaining popularity, there is a concurrent increase in running related injuries that up to 85% of novice runners incur an injury in a given year. Previous studies have utilized gait retraining program to successfully lower impact loading, which has been associated with many running ailments. However, softer footfalls may not necessarily prevent running injury. Purpose: To examine the vertical loading rates before and after the gait retraining as well as the effectiveness of the program on reducing the occurrence of running-related injury across a 12-month observation period. Study Design: Randomized controlled clinical trial Methods: A total of 320 novice runners from the local running club completed this study. All the participants underwent a baseline running biomechanics evaluation on an instrumented treadmill with their usual running shoes at 8 and 12 km/h. Participants were then randomly assigned into either the gait retraining or control group. In the gait retraining group (n=166), participants received a two-week real time visual feedback gait retraining. In the control group (n=154), participants received treadmill running exercise but without visual feedback on their performance. The training time was identical between the two groups. Participants’ running mechanics were reassessed after the training and their 12-35 month post-training injury profile was tracked using an online surveillance platform. Results: There was a significant reduction in the vertical loading rates at both testing speeds in the gait retraining group (p<0.001, Cohen’s d>0.99) whereas the loading rates were either similar or slightly increased in the control group after training (p=0.001 to 0.461, Cohen’s d=0.03 to -0.14). At 12-month follow-up, the occurrence of running-related musculoskeletal injury was 16% and 38% in the gait retraining and control group respectively. Hazard ratio between gait retraining and control groups was 0.383 (95%C.I.=0.25-0.59), indicating a 62% lower injury risk in gait retrained runners when compared with controls. Conclusion: A two-week gait retraining program is effective in lowering impact loading in novice runners. More importantly, the injury occurrence is 62% lower after two weeks of 46 running gait modification. Clinical Relevance: A two-week gait retraining program may lower impact loading, thus reducing the injury occurrence in novice runners.

Taylor JB, Nguyen A, Paterno MV, Huang B and Ford KR.   ”Real-time optimized bifeedback utilizing sport techniques (ROBUST): a study protocol for a randomized controlled trial.“ BMC Musculoskeletal Disorders (2017) 18:71. Background: Anterior cruciate ligament (ACL) injuries in female athletes lead to a variety of short- and long-term physical, financial, and psychosocial ramifications. While dedicated injury prevention training programs have shown promise, ACL injury rates remain high as implementation has not become widespread. Conventional prevention programs use a combination of resistance, plyometric, balance and agility training to improve high-risk biomechanics and reduce the risk of injury. While many of these programs focus on reducing knee abduction load and posture during dynamic activity, targeting hip extensor strength and utilization may be more efficacious, as it is theorized to be an underlying mechanism of injury in adolescent female athletes. Biofeedback training may complement traditional preventive training, but has not been widely studied in connection with ACL injuries. We hypothesize that biofeedback may be needed to maximize the effectiveness of neuromuscular prophylactic interventions, and that hip-focused biofeedback will improve lower extremity biomechanics to a larger extent than knee-focused biofeedback during dynamic sport-specific tasks and long-term movement strategies. Methods: This is an assessor-blind, randomized control trial of 150 adolescent competitive female (9–19 years) soccer players. Each participant receives 3x/week neuromuscular preventive training and 1x/week biofeedback, the mode depending on their randomization to one of 3 biofeedback groups (hip-focused, knee-focused, sham). The primary aim is to assess the impact of biofeedback training on knee abduction moments (the primary biomechanical predictor of future ACL injury) during double-leg landings, single-leg landings, and unplanned cutting. Testing will occur immediately before the training intervention, immediately after the training intervention, and 6 months after the training intervention to assess the long-term retention of modified biomechanics. Secondary aims will assess performance changes, including hip and core strength, power, and agility, and the extent to which maturation effects biofeedback efficacy. Discussion: The results of the Real-time Optimized Biofeedback Utilizing Sport Techniques (ROBUST) trial will help complement current preventive training and may lead to clinician-friendly methods of biofeedback to incorporate into widespread training practices. Trial registration: Date of publication in ClinicalTrials.gov: 20/04/2016. ClinicalTrials.gov Identifier: NCT02754700..

Hafer JF, Brown AM, deMille P, Hillstrom HJ, Garber CE.   ”The effect of a cadence retraining protocol on running biomechanics and efficiency: a pilot study.“ J Sports Sci. 2014 Nov 4:1-8. Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner's preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners' post-intervention preferred running form as decreased hip adduction angle and vertical loading rate.

Teran-Yengle P, Birkhofer R, Weber MA, Patton K, Thatcher E, Yack HJ.   ”Efficacy of Gait Training With Real-Time Biofeedback in Correcting Knee Hyperextension Patterns in Young Women.“ 2011 - J Orthop Sports Phys Ther. OBJECTIVES: To investigate the efficacy of real-time biofeedback provided during treadmill gait training for correcting knee hyperextension in asymptomatic female while walking. BACKGROUND:Knee hyperextension is associated with increased stress to the posterior capsule of the knee joint, anterior cruciate ligament (ACL), and anterior compartment of the tibiofemoral joint. Previous methods aimed at correcting knee hyperextension have shown limited success. Studies support the use of biofeedback to improve learning of motor skills. METHODS:Ten women, ages 18 to 39 years, with asymptomatic knee hyperextension during ambulation were provided with 6 sessions of real-time feedback of kinematic data (Visual3D) during treadmill training. Gait evaluations were performed pretraining, posttraining, and 1 month after the last training session. RESULTS:Improved control of knee hyperextension during over ground walking at 1.3 m/s was shown at posttraining and at 1 month post-training. CONCLUSION:The present study shows that knee sagittal plane kinematics can be influenced by gait re-training using real-time biofeedback. [PMID: 22030469]

Zeni J, Abujaber S, Flowers, P, Possi F, Snyder-Mackler L  ”Biofeedback to Promote Movement Symmetry After Total Knee Arthroplasty: A Feasibility Study. “ J Orthop Sports Phys Ther 2013;43(10):715-726. STUDY DESIGN: Prospective analysis of a longitudinal cohort with an embedded comparison group at a single time point. OBJECTIVES: To determine the feasibility and effectiveness of an outpatient rehabilitation protocol that includes movement symmetry biofeedback on functional and biomechanical outcomes after total knee arthroplasty (TKA). BACKGROUND: TKA reduces pain and improves functional ability, but many patients experience strength deficits and movement abnormalities in the operated limb, despite outpatient rehabilitation. These asymmetries increase load on the nonoperated limb, and greater asymmetry is related to worse functional outcomes. METHODS: Biomechanical and functional metrics were assessed 2 to 3 weeks prior to TKA, at discharge from outpatient physical therapy, and 6 months after TKA in 11 patients (9 men, 2 women; mean  SD age, 61.4  5.8 years; body mass index, 33.1  5.4 kg/m2) who received 6 to 8 weeks of outpatient physical therapy that included specialized symmetry training. Six-month outcomes were compared to a control group, matched by age, body mass index, and sex (9 men, 2 women; mean  SD age, 61.8  5 years; body mass index, 34.3  5.1 kg/m2), that did not receive specialized symmetry retraining. RESULTS: Of the 11 patients who received added symmetry training, 9 demonstrated clinically meaningful improvements that exceeded the minimal detectable change for all performance-based functional tests at 6 months post-TKA compared to pre-TKA. Six months after TKA, when walking, patients who underwent symmetry retraining had greater knee extension during midstance and had mean sagittal knee moments that were more symmetrical, biphasic, and more representative of normal knee kinetics compared to patients who did not undergo symmetry training. No patients experienced adverse events as the result of the protocol. CONCLUSION: Adding symmetry retraining to postoperative protocols is clinically viable, safe, and may have additional benefits compared to rehabilitation protocols that focus on range of motion, strength, and return to independence..

Back to Top

Takahashi KZ and Stanhope SJ. (2013) Mechanical energy profiles of the combined ankle-foot system in normal gait: insights for prosthetic designs. J Gait & Posture. 2013 Sep;38(4):818-23. Over the last half-century, the field of prosthetic engineering has continuously evolved with much attention being dedicated to restoring the mechanical energy properties of ankle joint musculatures during gait. However, the contributions of 'distal foot structures' (e.g., foot muscles, plantar soft tissue) have been overlooked. Therefore, the purpose of this study was to quantify the total mechanical energy profiles (e.g., power, work, and work-ratio) of the natural ankle-foot system (NAFS) by combining the contributions of the ankle joint and all distal foot structures during stance in level-ground steady state walking across various speeds (0.4, 0.6, 0.8 and 1.0 statures/s). The results from eleven healthy subjects walking barefoot indicated ankle joint and distal foot structures generally performed opposing roles: the ankle joint performed net positive work that systematically increased its energy generation with faster walking speeds, while the distal foot performed net negative work that systematically increased its energy absorption with faster walking speeds. Accounting for these simultaneous effects, the combined ankle-foot system exhibited increased work-ratios with faster walking. Most notably, the work-ratio was not significantly greater than 1.0 during the normal walking speed of 0.8 statures/s. Therefore, a prosthetic design that strategically exploits passive-dynamic properties (e.g., elastic energy storage and return) has the potential to replicate the mechanical energy profiles of the NAFS during level-ground steady-state walking.

Takahashi KZ, Kepple TM, Stanhope SJ. (2012) A unified deformable (UD) segment model for quantifying total power of anatomical and prosthetic below-knee structures during stance in gait. J Biomech. 2012 Oct 11;45(15):2662-7 Anatomically-relevant (AR) biomechanical models are traditionally used to quantify joint powers and segmental energies of lower extremity structures during gait. While AR models contain a series of rigid body segments linked together via mechanical joints, prosthetic below-knee structures are often deformable objects without a definable ankle joint. Consequently, the application of AR models for the study of prosthetic limbs has been problematic. The purpose of this study was to develop and validate a unified deformable (UD) segment model for quantifying the total power of below-knee structures. Estimates of total below-knee power derived via the UD segment model were compared to those derived via an AR model during stance in gait of eleven healthy subjects. The UD segment model achieved similar results to the AR model. Differences in peak power, total positive work, and total negative work were 1.91±0.31%, 3.97±0.49%, and 1.39±0.33%, relative to the AR model estimates. The main advantage of the UD segment model is that it does not require the definition of an ankle joint or foot structures. Therefore, this technique may be valuable for facilitating direct comparisons between anatomical and disparate prosthetic below-knee structures in future studies.
Back to Top

Gordon KE and Ferris DP (2007) Learning to walk with a robotic ankle exoskeleton Journal of Biomechanics, 40:2636-2644 We used a lower limb robotic exoskeleton controlled by the wearer's muscle activity to study human locomotor adaptation to disrupted muscular coordination. Ten healthy subjects walked while wearing a pneumatically powered ankle exoskeleton on one limb that effectively increased plantar flexor strength of the soleus muscle. Soleus electromyography amplitude controlled plantar flexion assistance from the exoskeleton in real time. We hypothesized that subjects' gait kinematics would be initially distorted by the added exoskeleton power, but that subjects would reduce soleus muscle recruitment with practice to return to gait kinematics more similar to normal. We also examined the ability of subjects to recall their adapted motor pattern for exoskeleton walking by testing subjects on two separate sessions, 3 days apart. The mechanical power added by the exoskeleton greatly perturbed ankle joint movements at first, causing subjects to walk with significantly increased plantar flexion during stance. With practice, subjects reduced soleus recruitment by approximately 35% and learned to use the exoskeleton to perform almost exclusively positive work about the ankle. Subjects demonstrated the ability to retain the adapted locomotor pattern between testing sessions as evidenced by similar muscle activity, kinematic and kinetic patterns between the end of the first test day and the beginning of the second. These results demonstrate that robotic exoskeletons controlled by muscle activity could be useful tools for testing neural mechanisms of human locomotor adaptation.
Back to Top

Olsen MT, Bruening DA, Johnson AW, Ridge ST (2019) The Role of the Midfoot in Drop Landings Medicine & Science in Sports & Exercise January 2019 - Volume 51 - Issue 1 - p 114–122 Purpose: The midfoot is instrumental to foot function; however, quantifying its roles in human movement has been difficult. A forceful dynamic activity like landing may help elucidate the midfoot’s contribution to foot energetics and function. The main purpose of this study was to measure midtarsal joint kinematics and kinetics during a barefoot single-leg landing task. A secondary aim of this study was to explore the relationship between static foot posture and dynamic midfoot function. Methods In a cross-sectional study design, 48 females (age = 20.4 ± 1.8 yr, body mass index = 21.6 ± 1.7 kg·m−1) performed drop landings from a height of 0.4 m onto split force platforms. Subjects hung from wooden rings and landed on their dominant leg. Midtarsal joint kinematic and kinetic data were recorded using a 14-camera optical motion capture system in conjunction with two in-ground force platforms and a custom kinetic three-segment foot model. Foot structure was measuring using the arch height index (AHI) and the static midtarsal joint angle from motion capture. Results: Kinematic data revealed an average sagittal plane midtarsal joint range of motion of 27° through the landing phase. Kinetic data showed that between 7% and 22% of the total lower extremity joint, work during the landing was performed by the midtarsal joint. Both standing AHI and static midtarsal joint angle (static MA) were correlated with sagittal plane midtarsal joint range of motion (standing AHI: r = −0.320, P = 0.026; static MA: r = 0.483, P < 0.001) and with midtarsal joint work (standing AHI: r = 0.332, P = 0.021; static MA: r = −0.323, P = 0.025). Conclusion: The midfoot contributes substantially to landing mechanics during a barefoot single-leg landing task. Static foot posture measures have limited value in predicting midfoot kinematics and kinetics during sportlike landings.

Kelly LA, Farris DJ, Lichtwark GA, Cresswell AG (2017) The Influence of Foot-Strike Technique on the Neuromechanical Function of the Foot Medicine & Science in Sports & Exercise. Purpose: The aim of this study was to investigate the influence of foot-strike technique on longitudinal arch mechanics and intrinsic foot muscle function during running. Methods: 13 healthy participants ran barefoot on a force-instrumented treadmill at 2.8ms-1 with a forefoot (FFS) and rear-foot (RFS, habitual) running technique, while kinetic, kinematic and electromyographic (EMG) data from the intrinsic foot muscles were collected simultaneously. The longitudinal arch was modeled as a single “mid-foot” joint representing motion of the rear-foot (calcaneus) relative to the forefoot (metatarsals). An inverse dynamic analysis was performed to estimate joint moments generated about the mid-foot, as well as mechanical work and power. Results: The mid-foot was more plantar flexed (higher arch) at foot contact when running with a forefoot running technique (RFS 0.2 ± 1.8o v FFS 6.9 ± 3.0o, ES = 2.7), however there was no difference in peak mid-foot dorsiflexion in stance (RFS -11.6 ± 3.0o v FFS -11.4 ± 3.4o, ES = 0.63). When running with a forefoot technique, participants generated greater moments about the mid-foot (27% increase, ES = 1.1) and performed more negative work (240% increase, ES = 2.2) and positive work (42% increase, ES = 1.1) about the mid-foot. Average stance phase muscle activation was greater for Flexor Digitorum Brevis (20% increase, ES = 0.56) and Abductor Hallucis (17% increase, ES = 0.63) when running with a forefoot technique. Conclusion: Forefoot running increases loading about the longitudinal arch and also increases the mechanical work performed by the intrinsic foot muscles. These findings have substantial implications in terms of injury prevention and management for runners who transition from a rear-foot to a forefoot running technique.

D.W. Powell; B Williams, RJ Butler (2013) A Comparison of Two Multisegment Foot Models in High and Low-Arched Athletes” Journal of the American Podiatric Medical Association Vol 103, No 2, March/April 2013. Background: Malalignment and dysfunction of the foot have been associated with an increased propensity for overuse and traumatic injury in athletes. Several multisegment foot models have been developed to investigate motions in the foot. However, it remains unknown whether the kinematics measured by different multisegment foot models are equivocal. The purpose of the present study is to examine the efficacy of two multisegment foot models in tracking aberrant foot function. Methods: Ten high-arched and ten low-arched female athletes walked and ran while ground reaction forces and three-dimensional kinematics were tracked using the Leardini and Oxford multisegment foot models. Ground reaction forces and joint angles were calculated with Visual 3D (C-Motion Inc, Germantown, MD). Repeated-measures analyses of variance were used to analyze peak eversion, time to peak eversion, and eversion excursions. Results: The Leardini model was more sensitive to differences in peak eversion angles than the Oxford model. However, the Oxford model detected differences in eversion excursion values that the Leardini model did not detect. Conclusions: Although both models found differences in frontal plane motion between high- and low-arched athletes, the Leardini multisegment foot model is suggested to be more appropriate as it directly tracks frontal plane midfoot motion during dynamicmotion. (J Am Podiatr Med Assoc 103(2): 99-105, 2013)

D.W. Powell; B Long, CE Milner, S Zhang (2011) Frontal plane multi-segment foot kinematics in high- and low-arched females during dynamic loading tasks. Human Movement Science“ Human Movement Science (30) 105–114. The functions of the medial longitudinal arch have been the focus of much research in recent years. Several studies have shown kinematic differences between high- and low-arched runners. No literature currently compares the inter-segmental foot motion of high and low-arched recreational athletes. The purpose of this study was to examine inter-segmental foot motion in the frontal plane during dynamic loading activities in high- and low-arched female athletes. Inter-segmental foot motions were examined in 10 highand 10 low-arched female recreational athletes. Subjects performed five barefooted trials in each of the following randomized movements: walking, running, downward stepping and landing. Three-dimensional kinematic data were recorded. High-arched athletes had smaller peak ankle eversion angles in walking, running and downward stepping than low-arched athletes. At the rear-midfoot joint high-arched athletes reached peak eversion later in walking and downward stepping than the low-arched athletes. The high-arched athletes had smaller peak mid-forefoot eversion angles in walking, running and downward stepping than the low-arched athletes. The current findings show that differences in foot kinematics between the high- and low-arched athletes were in position and not range of motion within the foot.

J. Wilken, S Rao, C Saltzman, HJ Yack   ”The effect of arch height on kinematic coupling during walking.“ 2011 - Clinical Biomechanics (26) 318-323. The purpose of the current study was to assess kinematic coupling within the foot in individuals across a range of arch heights. Seventeen subjects participated in this study. Weight-bearing lateral radiographs were used to measure the arch height, defined as angle between the 1st metatarsal and the calcaneus. A kinematic model including the 1st metatarsal, lateral forefoot, calcaneus and tibia was used to assess foot kinematics during walking. Four coupling ratios were calculated: calcaneus frontal to forefoot transverse plane motion (Calcaneal EV/Forefoot AB), calcaneus frontal to transverse plane motion (Calcaneus EV/AB), forefoot sagittal to transverse plane motion (Forefoot DF/AB), and 1st metatarsal sagittal to transverse plane motion (1st Metatarsal DF/AB). Pearson product moment correlations were used to assess the relationship between arch height and coupling ratios. Mean (SD) radiographic arch angles of 129.8 (12.1) degrees with a range from 114 to 153 were noted, underscoring the range of arch heights in this cohort. Arch height explained approximately 3%, 38%, 12% and 1% of the variance in Calcaneal EV/Forefoot AB, Calcaneus EV/AB, Forefoot DF/AB and 1st Metatarsal DF/AB respectively. Calcaneal EV/Forefoot AB, Calcaneus EV/AB, Forefoot DF/AB and 1st Metatarsal DF/AB coupling ratios of 1.84±0.80, 0.56±0.35, 0.96±0.27 and 0.43±0.21were noted, consistent with the twisted foot plate model, windlass mechanism and midtarsal locking mechanisms. Arch height had a small and modest relationship with kinematic coupling ratios during walking. [PMID: Reference]

Milner CE, Hamill J, Davis IS   ”Distinct hip and rearfoot kinematics in female runners with a history of tibial stress fracture“ 2010 - J Orthop Sports Phys Ther. 2010 Feb;40(2):59-66. STUDY DESIGN: Cross-sectional controlled laboratory study. OBJECTIVES: To investigate the kinematics of the hip, knee, and rearfoot in the frontal and transverse planes in female distance runners with a history of tibial stress fracture. BACKGROUND: Tibial stress fractures are a common overuse injury in runners, accounting for up to half of all stress fractures. Abnormal kinematics of the lower extremity may contribute to abnormal musculoskeletal load distributions, leading to an increased risk of stress fractures. METHODS: Thirty female runners with a history of tibial stress fracture were compared to 30 age-matched and weekly-running-distance-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected using a motion capture system and a force platform, respectively, as subjects ran in the laboratory. Selected variables of interest were compared between the groups using a multivariate analysis of variance (MANOVA). RESULTS: Peak hip adduction and peak rearfoot eversion angles were greater in the stress fracture group compared to the control group. Peak knee adduction and knee internal rotation angles and all joint angles at impact peak were similar between the groups. CONCLUSION: Runners with a previous tibial stress fracture exhibited greater peak hip adduction and rearfoot eversion angles during the stance phase of running compared to healthy controls. A consequence of these mechanics may be altered load distribution within the lower extremity, predisposing individuals to stress fracture. [PMID: 20118528 Reference]

Pohl MB, Hamill J, Davis IS.   ”Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners.“ 2009 - Clin J Sport Med. 2009 Sep;19(5):372-6.Click here to read OBJECTIVE: To compare selected structural and biomechanical factors between female runners with a history of plantar fasciitis and healthy control subjects. DESIGN: Cross-sectional. SETTING: University of Delaware Motion Analysis Laboratory, Newark, Delaware; and University of Massachusetts Biomechanics Laboratory, Amherst, Massachusetts. PARTICIPANTS: Twenty-five female runners with a history of plantar fasciitis were recruited for this study. A group of 25 age- and mileage-matched runners with no history of plantar fasciitis served as control subjects. INTERVENTIONS: The independent variable was whether or not subjects had a history of plantar fasciitis. MAIN OUTCOME MEASURES: Subjects ran overground while kinematic and kinetic data were recorded using a motion capture system and force plate. Rearfoot kinematic variables of interest included peak dorsiflexion, peak eversion, time to peak eversion along with eversion excursion. Vertical ground reaction force variables included impact peak and the maximum instantaneous load rate. Structural measures were taken for calcaneal valgus and arch index during standing and passive ankle dorsiflexion range of motion. RESULTS: A significantly greater maximum instantaneous load rate was found in the plantar fasciitis group along with an increased ankle dorsiflexion range of motion compared with the control group. The plantar fasciitis group had a lower arch index compared with control subjects, but calcaneal valgus was similar between groups. No differences in rearfoot kinematics were found between groups. CONCLUSION: These data indicate that a history of plantar fasciitis in runners may be associated with greater vertical ground reaction force load rates and a lower medial longitudinal arch of the foot.

Maclean CL, Davis IS, Hamill J.   ”Influence of running shoe midsole composition and custom foot orthotic intervention on lower extremity dynamics during running.“ 2009 - J Appl Biomech. 2009 Feb;25(1):54-63. The purpose of this study was to analyze the influence of varying running shoe midsole composition on lower extremity dynamics with and without a custom foot orthotic intervention. Three-dimensional dynamics were collected on 12 female runners who had completed 6 weeks of custom foot orthotic therapy. Participants completed running trials in 3 running shoe midsole conditions-with and without a custom foot orthotic intervention. Results from the current study revealed that only maximum rearfoot eversion velocity was influenced by the midsole durometer of the shoe. Maximum rearfoot eversion velocity was significantly decreased for the hard shoe compared with the soft shoe. However, the orthotic intervention in the footwear led to significant decreases in several dynamic variables. The results suggest that the major component influencing the rearfoot dynamics was the orthotic device and not the shoe composition. In addition, data suggest that the foot orthoses appear to compensate for the lesser shoe stability enabling it to function in a way similar to that of a shoe of greater stability.

MacLean C, McClay Davis I, and Hamill J   ”Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners.“| 2006 - Clinical Biomechanics, Volume 21, Issue 6, Pages 623-630

Butler RJ, Davis IS, and Hamill J   ”Interaction of arch type and footwear on running mechanics.“ 2006 - American Journal of Sports Medicine 34, 1998-2005 BACKGROUND: Running shoes are designed to accommodate various arch types to reduce the risk of lower extremity injuries sustained during running. Yet little is known about the biomechanical changes of running in the recommended footwear that may allow for a reduction in injuries. PURPOSE: To evaluate the effects of motion control and cushion trainer shoes on running mechanics in low- and high-arched runners. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty high-arched and 20 low-arched recreational runners (>10 miles per week) were recruited for the study. Three-dimensional kinematic and kinetics were collected as subjects ran at 3.5 ms(-1) +/- 5% along a 25-m runway. The motion control shoe evaluated was the New Balance 1122, and the cushioning shoe evaluated was the New Balance 1022. Repeated-measures analyses of variance were used to determine if low- and high-arched runners responded differently to motion control and cushion trainer shoes. RESULTS: A significant interaction was observed in the instantaneous loading rate such that the low-arched runners had a lower instantaneous loading rate in the motion control condition, and the high-arched runners had a lower instantaneous loading rate in the cushion trainer condition. Significant main effects for shoe were observed for peak positive tibial acceleration, peak-to-peak tibial acceleration, mean loading rate, peak eversion, and eversion excursion. CONCLUSION: These results suggest that motion control shoes control rearfoot motion better than do cushion trainer shoes. In addition, cushion trainer shoes attenuate shock better than motion control shoes do. However, with the exception of instantaneous loading rate, these benefits do not differ between arch type. CLINICAL RELEVANCE: Running footwear recommendations should be based on an individual's running mechanics. If a mechanical analysis is not available, footwear recommendations can be based empirically on the individual's arch type.|

Gordon KE, Sawicki GS and Ferris DP   ”Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis.“ 2006 - Journal of Biomechanics, 39:1832-1841

Ferris DP, Bohra ZA, Lukos JR and Kinnaird CR   ”Neuromechanical adaptation to hopping with an elastic ankle-foot orthosis.“ 2006 - Journal of Applied Physiology, 100:163-170

Turner DE, Helliwell PS, Emery P, and Woodburn J   ”The impact of rheumatoid arthritis on foot function in the early stages of disease: a clinical case series. BioMed Center Musculoskeletal Disorders.“ 2006 - BMC Musculoskeletal Disorders 2006, 7:102 Reference

Back to Top

Seay J, Selbie WS, Hamill J.   ”In vivo lumbo-sacral forces and moments during constant speed running at different stride lengths.“ 2008 - J Sports Sci. 2008 Nov 6:1-11. The aim of this study was to introduce a Newton-Euler inverse dynamics model that included reaction force and moment estimation at the lumbo-sacral (L5-S1) and thoraco-lumbar (T12-L1) joints. Data were collected while participants ran over ground at 3.8 m . s(-1) at three different stride lengths: preferred stride length, 20% greater than preferred, and 20% less than preferred. Inputs to the model were ground reaction forces, bilateral lower extremity and pelvis kinematics and inertial parameters, kinematics of the lumbar spine and thorax and inertial parameters of the lumbar segment. Repeated measures ANOVA were performed on the lower extremity sagittal kinematics and kinetics, including L5-S1 and T12-L1 three-dimensional joint angles, reaction forces and moments at touchdown and peak values during impact phase across the three stride conditions. Results indicated that L5-S1 and T12-L1 vertical reaction forces at touchdown and during the impact portion of the support phase increased significantly as stride length increased (P < 0.001), as did peak sagittal L5-S1 moments during impact (P = 0.018). Additionally, the transverse T12-L1 joint moment increased as running speed increased (P = 0.006). We concluded from our findings that our model was sensitive to our perturbations in healthy runners, and may prove useful in future mechanistic studies of L5-S1 mechanics.

Mitchell K, Porter M, Anderson L, Phillips C, Arceo G, Montz B, Levy S, and Gombatto SP(2017)   ”Differences in lumbar spine and lower extremity kinematics in people with and without low back pain during a step-up task: a cross-sectional study.“ BMC Musculoskeletal Disorders (2017) 18:369 Abstract Background: Low back pain (LBP) affects more than one third of the population at any given time, and chronic LBP is responsible for increased medical costs, functional limitations and decreased quality of life. A clear etiology is often difficult to identify, but aberrant posture and movement are considered contributing factors to chronic LBP that are addressed during physiotherapy intervention. Information about aberrant movement during functional activities in people with LBP can help inform more effective interventions. The purpose of this study was to determine if there are differences in lumbar spine and lower extremity kinematics in people with and without LBP during a step-up task. Methods: A convenience sample of 37 participants included 19 with LBP and 18 without a history of LBP. All participants were between the ages of 18 and 65, and controls were matched to participants with LBP based on age, gender and BMI. A motion capture system was used to record spine and lower extremity kinematics during the step-up task. ANOVA tests were used to determine differences in three-dimensional kinematics between groups. Results: Participants with LBP displayed less lower lumbar motion in the sagittal plane (P = 0.001), more knee motion in the coronal plane (P = 0.001), and more lower extremity motion in the axial plane (P = 0.002) than controls. Conclusions: People with LBP display less lower lumbar spine motion in the sagittal plane and more out-of-plane lower extremity motion. Clinically, the step-up task can be used to identify these aberrant movements to develop more focused functional interventions for patients with LBP.

D'Angelo K1, Triano JJ, Kawchuk GN, Howarth SJ(2016)   ”Patient-Induced Reaction Forces and Moments are Influenced by Variations in Spinal Manipulative Technique.“ 2008 - Spine Jun 6 PMID:27270638 STUDY DESIGN: An in vivo biomechanical study OBJECTIVE.: . The aim of the present study was to quantify and compare the reaction loads for two spinal manipulation therapy (SMT) procedures commonly used for low back pain using a biomechanical computer model. SUMMARY OF BACKGROUND DATA: Contemporary computer-driven rigid linked-segment models (LSMs) have made it feasible to analyze low back kinetics and kinematics during various activities including spinal manipulation therapy (SMT) procedures. Currently, a comprehensive biomechanical model analyzing actual differences in loading effects between different SMT procedures is lacking. METHODS: Twenty-four healthy/asymptomatic participants received a total of 6 SMT applications, representing all combinations of two similar SMT procedures within three patient hip flexion angles. All contact forces, patient torso kinematics, and inertial properties were entered into a dynamic three-dimensional LSM to calculate lumbar reaction forces and moments. Peak net applied force along with the maximums, minimums, and ranges for each component of the three-dimensional reaction force and moment vectors during each SMT procedure were analyzed. RESULTS: One specific SMT technique (lumbar spinous pull) produced greater maximum anterior-posterior reaction force and both lateral bending and axial twisting reaction moments when compared to the other technique (lumbar push procedure (all p ≤ 0.034)). SMT trials without hip flexion had lower maximum medial-lateral reaction force and range compared to those with 45 and 90 degrees of hip flexion (all p ≤ 0.041). There were no interactions between procedure and hip angle for any of the dependent measurements. CONCLUSION: The technique used to apply SMT and the participant's initial hip orientation induced significantly different actions on the low back. These findings and future research can improve patient outcomes and safety by informing clinicians on how to best utilize SMT given specific types of low back pain.

Howarth SJ, D'Angelo K, Triano JJ. (2016)   ”Development of a Linked Segment Model to Derive Patient Low Back Reaction Forces and Moments During High-Velocity Low-Amplitude Spinal Manipulation.“ 2008 - J Manipulative Physiol Ther. 2016 Mar-Apr;39(3):176-84. PMID: 27034108 OBJECTIVE: The purpose of this paper is to present the experimental setup, the development, and implementation of a new scalable model capable of efficiently handling data required to determine low back kinetics during high-velocity low-amplitude spinal manipulation (HVLA-SM). METHODS: The model was implemented in Visual3D software. All contact forces and moments between the patient and the external environment (2 clinician hand contact forces, 1 contact force between the patient and the treatment table), the patient upper body kinematics, and inertial properties were used as input. Spine kinetics and kinematics were determined from a single HVLA-SM applied to one healthy participant in a right side-lying posture to demonstrate the model's utility. The net applied force was used to separate the spine kinetic and kinematic time-series data from the HVLA-SM into preload as well as early and late impulse phases. RESULTS: Time-series data obtained from the HVLA-SM procedure showed that the participant's spine underwent left axial rotation, combined with extension, and a reduction in left lateral bending during the procedure. All components of the reaction force, as well as the axial twist and flexion/extension reaction moments demonstrated a sinusoidal pattern during the early and late impulse phases. During the early impulse phase, the participant's spine experienced a leftward axial twisting moment of 37.0 Nm followed by a rightward moment of -45.8 Nm. The lateral bend reaction moment exhibited a bimodal pattern during the early and late impulse phases. CONCLUSION: This model was the first attempt to directly measure all contact forces acting on the participant/patient's upper body, and integrate them with spine kinematic data to determine patient low back reaction forces and moments during HVLA-SM in a side-lying posture. Advantages of this model include the brevity of data collection (<1 hour), and adaptability for different patient anthropometries and clinician-patient contacts.

Back to Top

Neckel ND, Blonien N, Nichols D, Hidler J   ”Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern“ 2008 - J Neuroeng Rehabil. 2008; 5: 19. BACKGROUND: It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories. METHODS: A motion analysis system was used to track the kinematic patterns of the pelvis and legs of 10 chronic hemiparetic stroke subjects and 5 age matched controls as they walked in the Lokomat. The subject\\\\\\\'s legs were attached to the Lokomat using instrumented shank and thigh cuffs while instrumented footlifters were applied to the impaired foot of stroke subjects to aid with foot clearance during swing. With minimal body-weight support, subjects walked at 2.5 km/hr on an instrumented treadmill capable of measuring ground reaction forces. Through a custom inverse dynamics model, the ankle, knee, and hip joint torques were calculated in both the frontal and sagittal planes. A single factor ANOVA was used to investigate differences in joint torques between control, unimpaired, and impaired legs at various points in the gait cycle. RESULTS: While the kinematic patterns of the stroke subjects were quite similar to those of the control subjects, the kinetic patterns were very different. During stance phase, the unimpaired limb of stroke subjects produced greater hip extension and knee flexion torques than the control group. At pre-swing, stroke subjects inappropriately extended their impaired knee, while during swing they tended to abduct their impaired leg, both being typical abnormal torque synergy patterns common to stroke gait. CONCLUSION: Despite the Lokomat guiding stroke subjects through physiologically symmetric kinematic gait patterns, abnormal asymmetric joint torque patterns are still generated. These differences from the control group are characteristic of the hip hike and circumduction strategy employed by stroke subjects.

Keefer M, King J, Powell D, Krusenklaus JH, Zhang S   ”Effects of modified short-leg walkers on ground reaction force characteristics.“ 2008 - Keefer, M, King, J, Powell, D, Krusenklaus, JH, Zhang, S. Effects of modified short-leg walkers on ground reaction force characteristics. Clin Biomech (Bristol, Avon). 2008; 23(9):1172-7. BACKGROUND: Although short-leg walkers are often used in the treatment of lower extremity injuries (ankle and foot fractures and severe ankle sprains), little is known about the effect the short-leg walker on gait characteristics. The purpose was to examine how heel height modifications in different short-leg walkers and shoe side may affect ground reaction forces in walking. METHODS: Force platforms were used to collect ground reaction force data on 10 healthy participants. Five trials were performed in each of six conditions: lab shoes, gait walker, gait walker with heel insert on shoe side, gait walker modified with insert on walker side, equalizer walker, and equalizer walker with heel insert on shoe side. Conditions were randomized and walking speed was standardized between conditions. A 2×6 (sidexcondition) repeated analysis of variance was used on selected ground reaction force variables (P<0.05). FINDINGS: The application of a walker created peak vertical and anteroposterior ground reaction forces prior to the normal peaks associated with the loading response. Wearing a walker introduced an elevated minimum vertical ground reaction force in all conditions except the equalizer walker when compared to shoe on the shoe side. Peak propulsive anteroposterior ground reaction forces were smaller in all walker conditions compared to shoe on walker side. INTERPRETATION: The application of heel insert in gait walker with heel insert (on shoe side) and gait walker modified (on walker side) does not diminish the minimum vertical ground reaction force as hypothesized. Wearing a walker decreases the peak propulsive anteroposterior ground reaction force on the walker side and induces asymmetrical loading. Reference

Svehlika M, Slaby K, Soumar L, Smetanaa P, Kobesovac A, and Trca T  ”Evolution of walking ability after soft tissue surgery in cerebral palsy patients: what can we expect? “ 2008 - Journal of Pediatric Orthopaedics B 2008, 17:107–113 Eleven patients with spastic cerebral palsy were evaluated preoperatively, and 3 and 9 months postoperatively after soft tissue surgery. Evaluation included clinical examination, the Functional Mobility Scale questionnaire, and instrumented gait and center of mass trajectory analysis. A decrease in time–distance parameters after 3 months was followed by progress in all parameters at 9 months postoperatively. Push-off range of ankle motion decreased after surgery and was not restored to preoperative level until 9 months later. The center of mass vertical displacement improved significantly. The Functional Mobility Scale showed gait improvement. Despite the normalization of range of motion after surgery, there is an obvious period of functional gait deterioration in the early postoperative period and the push-off range of motion at the ankle did not recover to preoperative level until 9 months later.

Ramsey DK, Snyder-Mackler L, Lewek M, Newcomb W, Rudolph KS.   ”Effect of anatomic realignment on muscle function during gait in patients with medial compartment knee osteoarthritis.“ 2007 - rthritis Care & Research. Volume 57, Issue 3 , Pages 389 - 397

Willems, Tine Mariek, Witvrouw, Erik, De Cock, Anneleen, De Clercq, Dirk   ”Gait-Related Risk Factors for Exercise-Related Lower-Leg Pain during Shod Running.“ 2007 - Medicine & Science in Sports & Exercise. 39(2):330-339

Khan WS, Nokes L, Jones RK, Johnson DS   ”The relationship of the angle of immobilisation of the knee to the force applied to the extensor mechanism when partially weight-bearing. A Gait-Analysis Study in Normal Volunteers.“ 2007 - Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 7, 911-914

Zhang, S, Clowers, KG, Powell, D.   ”Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers“ 2006 - Zhang, S, Clowers, KG, Powell, D. Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers. Gait & Posture. 2006; 24(4):487-92. Short-leg walking boots offer several advantages over traditional casts. However, their effects on ground reaction forces (GRF) and three-dimensional (3D) biomechanics are not fully understood. The purpose of the study was to examine 3D lower extremity kinematics and joint dynamics during walking in two different short-leg walking boots. Eleven (five females and six males) healthy subjects performed five level walking trials in each of three conditions: two testing boot conditions, Gait Walker (DeRoyal Industries, Inc.) and Equalizer (Royce Medical Co.), and one pair of laboratory shoes (Noveto, Adidas). A force platform and a 6-camera Vicon motion analysis system were used to collect GRFs and 3D kinematic data during the testing session. A one-way repeated measures analysis of variance (ANOVA) was used to evaluate selected kinematic, GRF, and joint kinetic variables (p<0.05). The results revealed that both short-leg walking boots were effective in minimizing ankle eversion and hip adduction. Neither walker increased the bimodal vertical GRF peaks typically observed in normal walking. However, they did impose a small initial peak (<1BW) earlier in the stance phase. The Gait Walker also exhibited a slightly increased vertical GRF during midstance. These characteristics may be related to the sole materials/design, the restriction of ankle movements, and/or the elevated heel heights of the tested walkers. Both walkers appeared to increase the demand on the knee extensors while they decreased the demand of the knee and hip abductors based on the joint kinetic results. Reference

Buczek F, Cooney K, Walker M, Rainbow M, Concha M, Sanders JO   ”Performance of an inverted pendulum model directly applied to normal human gait.“ 2006 - Clinical Biomechanics, Volume 21, Issue 3, Pages 288-296

Siegel KL, Kepple TM, Stanhope SJ   ”A case study of gait compensations for hip muscle weakness in idiopathic inflammatory myopathy.“ 2007 - Clin Biomech (Bristol, Avon). 2007 Mar;22(3):319-26 BACKGROUND: The purpose of this case series was to quantify different strategies used to compensate in gait for hip muscle weakness. METHODS: An instrumented gait analysis was performed of three females diagnosed with idiopathic inflammatory myopathies and compared to a healthy unimpaired subject. Lower extremity joint moments obtained from the gait analysis were used to drive an induced acceleration model which determined each moment\\\'s contribution to upright support, forward progression, and hip joint acceleration. FINDINGS: Results showed that after midstance, the ankle plantar flexors normally provide upright support and forward progression while producing hip extension acceleration. In normal gait, the hip flexors eccentrically resist hip extension, but the hip flexor muscles of the impaired subjects (S1-3) were too weak to control extension. Instead S1-3 altered joint positions and muscle function to produce forward progression while minimizing hip extension acceleration. S1 increased knee flexion angle to decrease the hip extension effect of the ankle plantar flexors. S2 and S3 used either a knee flexor moment or gravity to produce forward progression, which had the advantage of accelerating the hip into flexion rather than extension, and decreased the demand on the hip flexors. INTERPRETATION: Results showed how gait compensations for hip muscle weakness can produce independent (i.e. successful) ambulation, although at a reduced speed as compared to normal gait. Knowledge of these successful strategies can assist the rehabilitation of patients with hip muscle weakness who are unable to ambulate and potentially be used to reduce their disability.

Back to Top

Hoglund LT1, Hillstrom HJ, Barr-Gillespie AE, Lockard MA, Barbe MF, Song J. (2014)   ”Frontal plane knee and hip kinematics during sit-to-stand and proximal lower extremity strength in persons with patellofemoral osteoarthritis: a pilot study.“ J Appl Biomech. 2014 Feb;30(1):82-94 Increased joint stress and malalignment are etiologic factors in osteoarthritis. Static tibiofemoral frontal plane malalignment is associated with patellofemoral osteoarthritis (PFOA). Patellofemoral joint stress is increased by activities such as sit-to-stand (STS); this stress may be even greater if dynamic frontal plane tibiofemoral malalignment occurs. If hip muscle or quadriceps weakness is present in persons with PFOA, aberrant tibiofemoral frontal plane movement may occur, with increased patellofemoral stress. No studies have investigated frontal plane tibiofemoral and hip kinematics during STS in persons with PFOA or the relationship of hip muscle and quadriceps strength to these motions. Eight PFOA and seven control subjects performed STS from a stool during three-dimensional motion capture. Hip muscle and quadriceps strength were measured as peak isometric force. The PFOA group demonstrated increased peak tibial abduction angles during STS, and decreased hip abductor, hip extensor, and quadriceps peak force versus controls. A moderate inverse relationship between peak tibial abduction angle and peak hip abductor force was present. No difference between groups was found for peak hip adduction angle or peak hip external rotator force. Dynamic tibiofemoral malalignment and proximal lower extremity weakness may cause increased patellofemoral stress and may contribute to PFOA incidence or progression.

Barrios JA, Higginson JS, Royer TD, Davis IS.   ”Static and dynamic correlates of the knee adduction moment in healthy knees ranging from normal to varus-aligned.“ 2009 - Clin Biomech (Bristol, Avon). 2009 Dec;24(10):850-4. Epub 2009 Aug 22. BACKGROUND: Individuals with medial knee osteoarthritis often present with varus knee alignment and ambulate with increased knee adduction moments. Understanding the factors that relate to the knee adduction moment in healthy individuals may provide insight into the development of this disease. Thus, this study aimed to examine the relationships of both static and dynamic lower extremity measures with the knee adduction moment. We hypothesized that the dynamic measures would be more closely related to this moment. METHODS: Arch height index, hip abduction strength and two static measures of knee alignment were recorded for 37 young asymptomatic knees that varied from normal to varus-aligned. Overground gait analyses were also performed. Correlation coefficients were used to assess the relationships between the static and dynamic variables to the knee adduction moment. Hierarchical regression analyses were then conducted using the static measures, the dynamic measures, and the static and dynamic measures together. RESULTS: Among the static measures, the tibial mechanical axis and the distance between the medial knee joint lines were correlated with the knee adduction moment. The best predictive static model (R(2)=0.53) included only the tibial mechanical axis. Among the dynamic variables, knee adduction and rearfoot eversion angles were correlated with the knee adduction moment. Knee adduction and rearfoot eversion, together, were the best dynamic model (R(2)=0.53). The static and dynamic measures together created the strongest of the three models (R(2)=0.59). CONCLUSIONS: These results suggest that dynamic measures slightly enhance the predictive strength of static measures when explaining variation in the knee adduction moment. [PMID: 19703728 Reference]

Back to Top

Apps C, Sterzing T, O’Brien T, Lake M(2016)   ”Lower limb joint stiffness and muscle co-contraction adaptations to instability footwear during locomotion.“ Journal of Electromyography and Kinesiology 31 (2016) 55–62 Abstract: Unstable shoes (US) continually perturb gait which can train the lower limb musculature, but muscle cocontraction and potential joint stiffness strategies are not well understood. A shoe with a randomly perturbing midsole (IM) may enhance these adaptations. This study compares ankle and knee joint stiffness, and ankle muscle co-contraction during walking and running in US, IM and a control shoe in 18 healthy females. Ground reaction forces, three-dimensional kinematics and electromyography of the gastrocnemius medialis and tibialis anterior were recorded. Stiffness was calculated during loading and propulsion, derived from the sagittal joint angle-moment curves. Ankle co-contraction was analysed during preactivation and stiffness phases. Ankle stiffness reduced and knee stiffness increased during loading in IM and US whilst walking (ankle, knee: p = 0.008, 0.005) and running (p < 0.001; p = 0.002). During propulsion, the opposite joint stiffness re-organisation was found in IM whilst walking (both joints p < 0.001). Ankle co-contraction increased in IM during pre-activation (walking: p = 0.001; running: p < 0.001), and loading whilst walking (p = 0.003), not relating to ankle stiffness. Results identified relative levels of joint stiffness change in unstable shoes, providing new evidence of how stability is maintained at the joint level.

Back to Top

Schulz, B (2011)   ”Minimum toe clearance adaptations to floor surface irregularity and gait speed.“ 2007 - Journal of Biomechanics 44 (2011) 1277–1284 Abstract: Toe speed during gait generally nears its maximum while its height reaches a local minima approximately halfway through swing phase. Trips are thought to frequently occur at these local minima (minimum toe clearance or MTC events) and trip risk has been quantified using the minimum distance between the toe and ground here (MTC). This study investigated MTC on floor surfaces with and without multiple small obstacles. After shoes and floor surfaces were digitized, 14 unimpaired subjects (half women) each traversed a 4.88 m walkway 4 times at slow, preferred, and fast speeds across surfaces with no obstacles, visible obstacles, and hidden obstacles. Both surfaces with obstacles had the same random obstacle configuration. Shoe and body segment motions were tracked using passive markers and MTC and joint kinematics calculated. All MTC and kinematic variables tested significantly increased with faster instructed gait speed except the likelihood of MTC event occurrence (local minima in minimum toe clearance trajectory when foot is in upper quartile of speed). MTC events were less frequent for swing phases on surfaces with obstacles (80% vs. 98% for no obstacles). MTC values, when present, were doubled by the presence of visible obstacles (22.277.3 mm vs. 11.175.7 mm) and further increased to 26.877.1 mm when these obstacles were hidden from view (all comparisons pr0.0003). These substantial floor surface-related changes in MTC event occurrences and values resulted from alterations in toe- and heel-clearance trajectories caused by subtle but significant changes in joint kinematics that did not exceed 10% each joint’s swing phase range of motion.

Enrique Pérez-Rizo, Marta Solís-Mozos, Juan Manuel Belda-Lois, Álvaro Page, Julian Taylor, Jose Luis Pons, Ángel Gil-Agudo (2012)   ”INSTRUMENTATION AND BIOMECHANICAL MODEL FOR KINEMATIC AND KINETIC ANALYSIS OF UPPER LIMBS DURING GAIT WITH CRUTCHES.“ Journal of Accessibility and Design for All(CC) JACCES, 2012 - 3(2): 127-148. ISSN: 2013-7087 Abstract: The goal of this study was to develop a three-dimensional kinematic and kinetic model of the right upper extremity and a Lofstrand crutch in order to analyze joint displacements and loads during crutch-assisted gait. A Lofstrand crutch was instrumented with a six-component load cell to measure forces and moments at the crutch tip. The crutch and the right upper extremity of a subject were instrumented with markers to obtain kinematic data. A biomechanical model based on rigid bodies was implemented in biomechanical analysis software. To demonstrate the functionality of the model, a pilot test was conducted on one healthy individual during Lofstrand crutch-assisted gait. The shoulder extended during the support phase and flexed in the swing phase, the elbow flexed during the swing, and the wrist remained in extension throughout the cycle. In the shoulder and elbow joints, the predominant reaction forces were upward, whereas the internal force moments were flexion and extension, respectively. This tool will be useful when it comes to identifying risk factors for joint pathology associated with pattern gait, aid design or crutch overuse.

Back to Top

Palmieri-Smith RM, Kreinbrink J, Ashton-Miller JA, and Wojtys EM   ”Association of Quadriceps and Hamstrings Cocontraction Patterns With Knee Joint Loading“ 2009 - Journal of Athletic Training 2009;44(3):256–263 CONTEXT: Sex differences in neuromuscular control of the lower extremity have been identified as a potential cause for the greater incidence of anterior cruciate ligament (ACL) injuries in female athletes compared with male athletes. Women tend to land in greater knee valgus with higher abduction loads than men. Because knee abduction loads increase ACL strain, the inability to minimize these loads may lead to ACL failure. OBJECTIVE: To investigate the activation patterns of the quadriceps and hamstrings muscles with respect to the peak knee abduction moment. DESIGN: Cross-sectional study. SETTING: Neuromuscular research laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-one recreationally active adults (11 women, 10 men). MAIN OUTCOME MEASURE(S): Volunteers performed 3 trials of a 100-cm forward hop. During the hop task, we recorded surface electromyographic data from the medial and lateral hamstrings and quadriceps and recorded lower extremity kinematics and kinetics. Lateral and medial quadriceps-to-hamstrings (QratioH) cocontraction indices, the ratio of medial-to-lateral QratioH cocontraction, normalized root mean square electromyographic data for medial and lateral quadriceps and hamstrings, and peak knee abduction moment were calculated and used in data analyses. RESULTS: Overall cocontraction was lower in women than in men, whereas activation was lower in the medial than in the lateral musculature in both sexes (P < .05). The medial QratioH cocontraction index (R(2) = 0.792) accounted for a significant portion of the variance in the peak knee abduction moment in women (P = .001). Women demonstrated less activation in the vastus medialis than in the vastus lateralis (P = .49) and less activation in the medial hamstrings than in the lateral hamstrings (P = .01). CONCLUSIONS: Medial-to-lateral QratioH cocontraction appears to be unbalanced in women, which may limit their ability to resist abduction loads. Because higher abduction loads increase strain on the ACL, restoring medial-to-lateral QratioH cocontraction balance in women may help reduce ACL injury risk. Reference

Drewniak E, Jay G, Fleming B, Crisco J   ”Comparison of two methods for calculating the frictional properties of articular cartilage using a simple pendulum and intact mouse knee joints“ 2009 - Journal of Biomechanics, Volume 42, Issue 12, Pages 1996-1999 In attempts to better understand the etiology of osteoarthritis, a debilitating joint disease that results in the degeneration of articular cartilage (AC) in synovial joints, researchers have focused on joint tribology, the study of joint friction, lubrication, and wear. Several different approaches have been used to investigate the frictional properties of articular cartilage. In this study, we examined two analysis methods for calculating the coefficient of friction (μ) using a simple pendulum system and BL6 murine knee joints (n=10) as the fulcrum. A Stanton linear decay model (Lin μ) and an exponential model that accounts for viscous damping (Exp μ) were fit to the decaying pendulum oscillations. Root mean square error (RMSE), asymptotic standard error (ASE), and coefficient of variation (CV) were calculated to evaluate the fit and measurement precision of each model. This investigation demonstrated that while Lin μ was more repeatable, based on CV (5.0% for Lin μ; 18% for Exp μ), Exp μ provided a better fitting model, based on RMSE (0.165° for Exp μ; 0.391° for Lin μ) and ASE (0.033 for Exp μ; 0.185 for Lin μ), and had a significantly lower coefficient of friction value (0.022±0.007 for Exp μ; 0.042±0.016 for Lin μ) (p=0.001). This study details the use of a simple pendulum for examining cartilage properties in situ that will have applications investigating cartilage mechanics in a variety of species. The Exp μ model provided a more accurate fit to the experimental data for predicting the frictional properties of intact joints in pendulum systems.

O'Connor K, Bottum MC   ”Differences in Cutting Knee Mechanics Based on Principal Components Analysis“ 2009 - Medicine & Science in Sports & Exercise: April 2009 - Volume 41 - Issue 4 - pp 867-878 Purpose: The increased number of women participating in sports has led to a higher knee injury rate in women compared with men. Analysis of injury risk is limited to identification of discrete-dependent variables, but analysis of the entire waveform using principal components analysis (PCA) may provide greater insight. The purpose of this study was to examine gender differences in cutting knee mechanics using PCA and to compare these findings to those based on traditional discrete measures. Methods: Sixteen male and 17 female recreational athletes were recruited to perform unanticipated run and cutting tasks. Three-dimensional joint dynamics were recorded, and discrete variables were extracted. PCA analyses were also performed on the angle and moment waveforms in all three planes. The PCA used an eigenvalue analysis on the data covariance matrix. Gender differences in the principal component (PC) scores generated by the PCA were assessed using a MANOVA (P < 0.05). Results: On the basis of the discrete variables, flexion range of motion for females was less than for males. From the PCA analysis, females were less internally rotated during late stance and exhibited a relatively greater peak adduction moment that was not apparent in the original time series. This peak moment correlated with a greater abduction oscillation during early stance. There was also less variability for females in the sagittal and frontal plane moment PC. Conclusions: The PCA analysis did not significantly detect the decreased flexion, but PCA did reveal gender differences in movement patterns and variability that were not apparent in the discrete variables. The results of this study demonstrate the potential of PCA to provide deeper understand of movement dynamics that may help in detecting injury risk factors.

Schmitt LC, Rudolph KS   ”Muscle stabilization strategies in people with medial knee osteoarthritis: The effect of instability“ 2008 - Journal of Orthopaedic Research Journal of Orthopaedic Research Volume 26 Issue 9, Pages 1180 - 1185 The sensation of knee instability (shifting, buckling. and giving way) is common in people with medial knee osteoarthritis (OA). Its influence on knee stabilization strategies is unknown. This study investigated the influence of knee instability on muscle activation during walking when knee stability was challenged. Twenty people with medial knee OA participated and were grouped as OA Stable (OAS) (n = 10) and OA Unstable (OAU) (n = 10) based on self-reported knee instability during daily activities. Quadriceps strength, passive knee laxity, and varus alignment were assessed and related to knee instability and muscle cocontraction during walking when the support surface translated laterally. Few differences in knee joint kinematics between the groups were seen; however, there were pronounced differences in muscle activation. The OAU group used greater medial muscle cocontraction before, during, and following the lateral translation. Self-reported knee instability predicted medial muscle cocontraction, but medial laxity and limb alignment did not. The higher muscle cocontraction used by the OAU subjects appears to be an ineffective strategy to stabilize the knee. Instability and high cocontraction can be detrimental to joint integrity, and should be the focus of future research.

Goldberg EJ, Requejo PS, Fowler EG   ”The effect of direct measurement versus cadaver estimates of anthropometry in the calculation of joint moments during above-knee prosthetic gait in pediatrics“ 2008 - Journal of Biomechanics 41 (2008) 695-800 Joint reaction forces, moments and powers are important in interpreting gait mechanics and compensatory strategies used by patients walking with above-knee prostheses. Segmental anthropometrics, required to calculate joint moments, are often estimated using data from cadaver studies. However, these values may not be accurate for patients following amputation as prostheses are composed of nonbiologic material. The purpose of this study was to compare joint moments using anthropometrics calculated from cadaver studies versus direct measurements of the residual limb and prosthesis for children with an above-knee amputation. Gait data were collected for four subjects with above-knee prostheses walking at preferred and fast speeds. Joint moments were computed using anthropometrics from cadaver studies and direct measurements for each subject. The difference between these two methods primarily affected the inertia couple (Ia term) and the inertial effect due to gravity, which comprised a greater percentage of the total joint moment during swing as compared to stance. Peak hip and knee flexor and extensor moments during swing were significantly greater when calculated using cadaver data (po0.05). These differences were greater while walking fast as compared to slow speeds. A significant difference was not found between these two methods for peak hip and knee moments during stance. A significant difference was found for peak ankle joint moments during stance, but the magnitude was not clinically important. These results support the use of direct measurements of anthropometry when examining above-knee prosthetic gait, particularly during swing.

Farrokhi S, Pollard CD, Souza RB, Chen YJ, Reischl S, Powers CM.   ”Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise.“ 2008 - J Orthop Sports Phys Ther. 2008 Jul;38(7):403-9. Epub 2008 Apr 15 STUDY DESIGN: Experimental laboratory study. OBJECTIVES: To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. BACKGROUND: Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations. METHODS AND MEASURES: Ten healthy adults (5 males, 5 females; mean age +/- SD, 26.7 +/- 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions. RESULTS: During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P<.015) when compared to the NL condition. During the LTE condition, a significant increase was noted in peak ankle dorsiflexion and a significant decrease was noted in peak hip flexion angle (P<.015) compared to the NL condition. CONCLUSIONS: Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature. LEVEL OF EVIDENCE: Therapy, level 5.

Ramsey DK, Briem K, Axe MJ, and Snyder-Mackler L   ”A Mechanical Theory for the Effectiveness of Bracing for Medial Compartment Osteoarthritis of the Knee.“ 2007 - The Journal of Bone and Joint Surgery (American) 89:2398-2407

Rudolph KS, Schmitt LC, and Lewek MD   ”Age-Related Changes in Strength, Joint Laxity, and Walking Patterns: Are They Related to Knee Osteoarthritis?“ 2007 - PHYS THER, Vol. 87, No. 11, 1422-1432 Background and Purpose Aging is associated with musculoskeletal changes and altered walking patterns. These changes are common in people with knee osteoarthritis (OA) and may precipitate the development of OA. We examined age-related changes in musculoskeletal structures and walking patterns to better understand the relationship between aging and knee OA. Methods Forty-four individuals without OA (15 younger, 15 middle-aged, 14 older adults) and 15 individuals with medial knee OA participated. Knee laxity, quadriceps femoris muscle strength (force-generating capacity), and gait were assessed. Results Medial laxity was greater in the OA group, but there were no differences between the middle-aged and older control groups. Quadriceps femoris strength was less in the older control group and in the OA group. During the stance phase of walking, the OA group demonstrated less knee flexion and greater knee adduction, but there were no differences in knee motion among the control groups. During walking, the older control group exhibited greater quadriceps femoris muscle activity and the OA group used greater muscle co-contraction. Discussion and Conclusion Although weaker, the older control group did not use truncated motion or higher co-contraction. The maintenance of movement patterns that were similar to the subjects in the young control group may have helped to prevent development of knee OA. Further investigation is warranted regarding age-related musculoskeletal changes and their influence on the development of knee OA.

Tokuno CD, Carpenter MG, Thorstensson A, Garland SJ, and Cresswell AG   ”Control of the triceps surae during the postural sway of quiet standing.“ 2007 - Acta Physiologica, Volume 191 Issue 3 Page 229-236

Segers V, Aerts P, Lenoir M, De Clercq, D   ”Dynamics of the body centre of mass during actual acceleration across transition speed.“ 2007 - Journal Exp Biol 310, 578-585 Judged by whole body dynamics, walking and running in humans clearly differ. When walking, potential and kinetic energy fluctuate out-of-phase and energy is partially recovered in a pendulum-like fashion. In contrast, running involves in-phase fluctuations of the mechanical energy components of the body centre of mass, allowing elastic energy recovery. We show that, when constantly accelerating across the transition speed, humans make the switch from walking to running abruptly in one single step. In this step, active mechanical energy input triples the normal step-by-step energy increment needed to power the imposed constant acceleration. This extra energy is needed to launch the body into the flight phase of the first running step and to bring the trunk into its more inclined orientation during running. Locomotor cycles immediately proceed with the typical in-phase fluctuations of kinetic and potential energy. As a result, the pendular energy transfer drops in one step from 43% to 5%. Kinematically, the transition step is achieved by landing with the knee and hip significantly more flexed compared to the previous walking steps. Flexion in these joints continues during the first half of stance, thus bringing the centre of mass to its deepest position halfway through stance phase to allow for the necessary extension to initiate the running gait. From this point of view, the altered landing conditions seem to constitute the actual transition.

Ramsey DK, Snyder-Mackler L, Lewek M, Newcomb W, Rudolph KS.   ”Effect of anatomic realignment on muscle function during gait in patients with medial compartment knee osteoarthritis.“ 2007 - rthritis Care & Research. Volume 57, Issue 3 , Pages 389 - 397

Willems, Tine Mariek, Witvrouw, Erik, De Cock, Anneleen, De Clercq, Dirk   ”Gait-Related Risk Factors for Exercise-Related Lower-Leg Pain during Shod Running.“ 2007 - Medicine & Science in Sports & Exercise. 39(2):330-339

Domingo A, Sawicki GS, Ferris DP.   ”Kinematics and muscle activity of individuals with incomplete spinal cord injury during treadmill stepping with and without manual assistance.“ 2007 - Journal of Neuroengineering and Rehabilitation 4:32 Background Treadmill training with bodyweight support and manual assistance improves walking ability of patients with neurological injury. The purpose of this study was to determine how manual assistance changes muscle activation and kinematic patterns during treadmill training in individuals with incomplete spinal cord injury. Methods We tested six volunteers with incomplete spinal cord injury and six volunteers with intact nervous systems. Subjects with spinal cord injury walked on a treadmill at six speeds (0.18–1.07 m/s) with body weight support with and without manual assistance. Healthy subjects walked at the same speeds only with body weight support. We measured electromyographic (EMG) and kinematics in the lower extremities and calculated EMG root mean square (RMS) amplitudes and joint excursions. We performed cross-correlation analyses to compare EMG and kinematic profiles. Results Normalized muscle activation amplitudes and profiles in subjects with spinal cord injury were similar for stepping with and without manual assistance (ANOVA, p > 0.05). Muscle activation amplitudes increased with increasing speed (ANOVA, p < 0.05). When comparing spinal cord injury subject EMG data to control subject EMG data, neither the condition with manual assistance nor the condition without manual assistance showed a greater similarity to the control subject data, except for vastus lateralis. The shape and timing of EMG patterns in subjects with spinal cord injury became less similar to controls at faster speeds, especially when walking without manual assistance (ANOVA, p < 0.05). There were no consistent changes in kinematic profiles across spinal cord injury subjects when they were given manual assistance. Knee joint excursion was ~5 degrees greater with manual assistance during swing (ANOVA, p < 0.05). Hip and ankle joint excursions were both ~3 degrees lower with manual assistance during stance (ANOVA, p < 0.05). Conclusion Providing manual assistance does not lower EMG amplitudes or alter muscle activation profiles in relatively higher functioning spinal cord injury subjects. One advantage of manual assistance is that it allows spinal cord injury subjects to walk at faster speeds than they could without assistance. Concerns that manual assistance will promote passivity in subjects are unsupported by our findings. Reference

Gordon KE and Ferris DP   ”Learning to walk with a robotic ankle exoskeleton“ 2007 - Journal of Biomechanics, 40:2636-2644 We used a lower limb robotic exoskeleton controlled by the wearer's muscle activity to study human locomotor adaptation to disrupted muscular coordination. Ten healthy subjects walked while wearing a pneumatically powered ankle exoskeleton on one limb that effectively increased plantar flexor strength of the soleus muscle. Soleus electromyography amplitude controlled plantar flexion assistance from the exoskeleton in real time. We hypothesized that subjects' gait kinematics would be initially distorted by the added exoskeleton power, but that subjects would reduce soleus muscle recruitment with practice to return to gait kinematics more similar to normal. We also examined the ability of subjects to recall their adapted motor pattern for exoskeleton walking by testing subjects on two separate sessions, 3 days apart. The mechanical power added by the exoskeleton greatly perturbed ankle joint movements at first, causing subjects to walk with significantly increased plantar flexion during stance. With practice, subjects reduced soleus recruitment by approximately 35% and learned to use the exoskeleton to perform almost exclusively positive work about the ankle. Subjects demonstrated the ability to retain the adapted locomotor pattern between testing sessions as evidenced by similar muscle activity, kinematic and kinetic patterns between the end of the first test day and the beginning of the second. These results demonstrate that robotic exoskeletons controlled by muscle activity could be useful tools for testing neural mechanisms of human locomotor adaptation.

Palmieri-Smith RM, Kreinbrink J, Ashton-Miller JA, and Wojtys EM   ”Quadriceps Inhibition Induced by an Experimental Knee Joint Effusion Affects Knee Joint Mechanics During a Single-Legged Drop Landing.“ 2007 - Am J Sports Med. 35: 1269-1275 Background: Arthrogenic quadriceps muscle inhibition accompanies knee joint effusion and impedes rehabilitation after knee joint injury. Hypothesis: We hypothesized that an experimentally induced knee joint effusion would cause arthrogenic quadriceps muscle inhibition and lead to increased ground reaction forces, as well as sagittal plane knee angles and moments, during a single-legged drop landing. Study Design: Controlled laboratory study. Methods: Nine subjects (4 women and 5 men) underwent 4 conditions (no effusion, lidocaine injection, “low” effusion [30 mL], and “high” effusion [60 mL]) and then performed a single-legged drop landing. Lower extremity muscle activity, peak sagittal plane knee flexion angles, net sagittal plane knee moments, and peak ground reaction forces were measured. Results: Vastus medialis and lateralis activity were decreased during the low and high effusion conditions (P < .05). However, increases in peak ground reaction forces and decreases in peak knee flexion angle and net knee extension moments occurred only during the high effusion condition (P < .05).Conclusions: Knee joint effusion induced quadriceps inhibition and altered knee joint mechanics during a landing task. Subjects landed with larger ground reaction forces and in greater knee extension, thereby suggesting that more force will be transferred to the knee joint and its passive restraints when quadriceps inhibition is present. Clinical Relevance: Knee joint effusion results in arthrogenic quadriceps muscle inhibition, increasing loading about the knee that may potentially increase the risk of future knee joint trauma or degeneration.

Myer GD, Ford F, Khoury J, Hewett TE   ”Clinical correlates to laboratory measures for use in non-contact anterior cruciate ligament injury risk prediction algorithm.“ 2007 - Clinical Biomechanics 25 (2010) 693–699 Background: Prospective measures of high knee abduction moment during landing identify female athletes at high risk for non-contact anterior cruciate ligament injury. Biomechanical laboratory measurements predict high knee abduction moment landing mechanics with high sensitivity (85%) and specificity (93%). The purpose of this study was to identify correlates to laboratory-based predictors of high knee abduction moment for use in a clinic-based anterior cruciate ligament injury risk prediction algorithm. The hypothesis was that clinically obtainable correlates derived from the highly predictive laboratory-based models would demonstrate high accuracy to determine high knee abduction moment status. Methods: Female basketball and soccer players (N=744) were tested for anthropometrics, strength and landing biomechanics. Pearson correlation was used to identify clinically feasible correlates and logistic regression to obtain optimal models for high knee abduction moment prediction. Findings: Clinical correlates to laboratory-based measures were identified and predicted high knee abduction moment status with 73% sensitivity and 70% specificity. The clinic-based prediction algorithm, including(Odds Ratio: 95% confidence interval) knee valgus motion (1.43:1.30–1.59 cm), knee flexion range of motion (0.98:0.96–1.01°), body mass (1.04:1.02–1.06 kg), tibia length (1.38:1.25–1.52 cm) and quadriceps to hamstring ratio (1.70:1.06–2.70) predicted high knee abduction moment status with C statistic 0.81. Interpretation: The combined correlates of increased knee valgus motion, knee flexion range of motion, body mass, tibia length and quadriceps to hamstrings ratio predict high knee abduction moment status in female athletes with high sensitivity and specificity. Clinical Relevance: Utilization of clinically obtainable correlates with the prediction algorithm facilitates high non-contact anterior cruciate ligament injury risk athletes' entry into appropriate interventions with the greatest potential to prevent injury.

Wheat JS, Vernon T, Milner CE   ”The measurement of upper body alignment during the golf drive.“ 2007 - Journal of Sports Sciences, 25(7):749-755

Khan WS, Nokes L, Jones RK, Johnson DS   ”The relationship of the angle of immobilisation of the knee to the force applied to the extensor mechanism when partially weight-bearing. A Gait-Analysis Study in Normal Volunteers.“ 2007 - Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 7, 911-914
Chow JY, Davids K, Button C, Koh M   ”Variation in Coordination of a Discrete Multiarticular Action as a Function of Skill Level.“ 2007 - Journal of Motor Behavior, Volume 39, Number 6, 463 - 479

Mizner RL, Snyder-Mackler L   ”Altered loading during walking and sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.“ 2006 - Journal of Orthopaedic Research Volume 23, Issue 5 , Pages 1083 - 1090 Total knee arthroplasty (TKA) successfully reduces pain, but has not achieved comparable improvements in function. We hypothesized that quadriceps strength affects performance by altering loading and movement patterns during functional tasks. METHODS: Fourteen subjects with isolated, unilateral TKA were tested three months after surgery. Quadriceps strength was assessed isometrically and kinematics, kinetics, and EMG were collected during level walking and sit-to-stand (STS). Function was assessed using the timed up and go test (TUG), stair climbing test (SCT), and the 6 min walk test (6MW). RESULTS: Functional performance was significantly related to the quadriceps strength of both legs, but was more strongly related to the uninvolved strength (involved rho=-0.43 with TUG; -0.65 with SCT; 0.64 with 6MW) (uninvolved rho=-0.63 with TUG; -0.68 with SCT; 0.77 with 6MW). During STS, subjects shifted weight away from the operated limb

Milner CE, Ferber R, Pollard CD, Hamill J, Davis IS   ”Biomechanical Factors Associated with Tibial Stress Fracture in Female Runners“ 2006 - Med. Sci. Sports Exerc., Vol. 38, No. 2, pp. 323–328, 2006 MILNER, C. E., R. FERBER, C. D. POLLARD, J. HAMILL, and I. S. DAVIS. Biomechanical Factors Associated with Tibial Stress Fracture in Female Runners. Med. Sci. Sports Exerc., Vol. 38, No. 2, pp. 323–328, 2006. Purpose: Tibial stress fractures (TSF) are among the most serious running injuries, typically requiring 6–8 wk for recovery. This cross-sectional study was conducted to determine whether differences in structure and running mechanics exist between trained distance runners with a history of prior TSF and those who have never sustained a fracture. Methods: Female runners with a rearfoot strike pattern, aged between 18 and 45 yr and running at least 32 kmIwkj1, were recruited for this study. Participants in the study were 20 subjects with a history of TSF and 20 ageand mileage-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected during overground running at 3.7 mIsj1 using a six-camera motion capture system, force platform, and accelerometer. Variables of interest were vertical impact peak, instantaneous and average vertical loading rates, instantaneous and average loading rates during braking, knee flexion excursion, ankle and knee stiffness, and peak tibial shock. Tibial varum was measured in standing. Tibial area moment of inertia was calculated from tibial x-ray studies for a subset of runners. Results: The TSF group had significantly greater instantaneous and average vertical loading rates and tibial shock than the control group. The magnitude of tibial shock predicted group membership successfully in 70% of cases. Conclusion: These data indicate that a history of TSF in runners is associated with increases in dynamic loading-related variables. Key Words: GROUND REACTION FORCES, KINEMATICS, TIBIAL SHOCK, AREA MOMENT OF INERTIA

MacLean C, McClay Davis I, and Hamill J   ”Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners.“ 2006 - Clinical Biomechanics, Volume 21, Issue 6, Pages 623-630

Butler RJ, Davis IS, and Hamill J   ”Interaction of arch type and footwear on running mechanics.“ 2006 - American Journal of Sports Medicine 34, 1998-2005 BACKGROUND: Running shoes are designed to accommodate various arch types to reduce the risk of lower extremity injuries sustained during running. Yet little is known about the biomechanical changes of running in the recommended footwear that may allow for a reduction in injuries. PURPOSE: To evaluate the effects of motion control and cushion trainer shoes on running mechanics in low- and high-arched runners. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty high-arched and 20 low-arched recreational runners (>10 miles per week) were recruited for the study. Three-dimensional kinematic and kinetics were collected as subjects ran at 3.5 ms(-1) +/- 5% along a 25-m runway. The motion control shoe evaluated was the New Balance 1122, and the cushioning shoe evaluated was the New Balance 1022. Repeated-measures analyses of variance were used to determine if low- and high-arched runners responded differently to motion control and cushion trainer shoes. RESULTS: A significant interaction was observed in the instantaneous loading rate such that the low-arched runners had a lower instantaneous loading rate in the motion control condition, and the high-arched runners had a lower instantaneous loading rate in the cushion trainer condition. Significant main effects for shoe were observed for peak positive tibial acceleration, peak-to-peak tibial acceleration, mean loading rate, peak eversion, and eversion excursion. CONCLUSION: These results suggest that motion control shoes control rearfoot motion better than do cushion trainer shoes. In addition, cushion trainer shoes attenuate shock better than motion control shoes do. However, with the exception of instantaneous loading rate, these benefits do not differ between arch type. CLINICAL RELEVANCE: Running footwear recommendations should be based on an individual's running mechanics. If a mechanical analysis is not available, footwear recommendations can be based empirically on the individual's arch type.

Whatling GM, Holt CA, Jones L, Madete JK, Dabke H, Alderman PM and Roberts P   ”Investigating the effects of surgical approach on total hip arthroplasty recovery using 3D gait analysis.“ 2006 - Ninth international symposium on teh 3D analysis of Human Movement

Gordon KE, Sawicki GS and Ferris DP   ”Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis.“ 2006 - Journal of Biomechanics, 39:1832-1841

Ferris DP, Bohra ZA, Lukos JR and Kinnaird CR   ”Neuromechanical adaptation to hopping with an elastic ankle-foot orthosis.“ 2006 - Journal of Applied Physiology, 100:163-170

Buczek F, Cooney K, Walker M, Rainbow M, Concha M, Sanders JO   ”Performance of an inverted pendulum model directly applied to normal human gait.“ 2006 - Clinical Biomechanics, Volume 21, Issue 3, Pages 288-296

Turner DE, Helliwell PS, Emery P, and Woodburn J   ”The impact of rheumatoid arthritis on foot function in the early stages of disease: a clinical case series. BioMed Center Musculoskeletal Disorders.“ 2006 - BMC Musculoskeletal Disorders 2006, 7:102 Reference

Stensdotter AK, Holmgren C, Dal?n T, H?ger-Ross C   ”The role of M. popliteus in unpredictable and in self-initiated balance provocations.“ 2006 - Journal of Orthopaedic Research, Volume 24, Issue 3 , Pages 524 - 530

Turner DE, Davys HJ & Woodburn J   ”Foot function following forefoot reconstruction in rheumatoid arthritis.“ 2005 - Australasian Journal of Podiatric Medicine; Vol 39, No.4 : 83-89

Goulermas JY, Howard D, Nester CJ, Jones RE, Ren L   ”Regression Techniques for the Prediction of Lower Limb Kinematics.“ 2005 - Journal of Biomechanical Engineering, Volume 127, Issue 6, pp. 1020-1024

Pollard CD, McClay Davis I, Hamill J   ”Influence of gender on hip and knee mechanics during a randomly cued cutting maneuver“ 2004 - Clinical Biomechanics, 19, 1022-1031

Siegel, KL, Kepple, TM, & Stanhope SJ   ”Joint moment control of mechanical energy flow during normal gait.“ 2004 - Gait and Posture, 19, 69-75

Woodburn J, Nelson KM, Siegel KL, Kepple TM, Gerber LH   ”Multisegment Foot Motion During Gait: Proof of Concept in Rheumatoid Arthritis.“ 2004 - The Journal of Rheumatology 31:10 OBJECTIVE: To test a multisegment foot model for kinematic analysis during barefoot walking in patients with well established rheumatoid arthritis (RA) and foot impairments. METHODS: Five healthy adult subjects and 11 RA patients with advanced disease were studied. Foot impairments were assessed using standardized outcomes and clinical examination techniques. A 6-camera 60 Hz video-based motion analysis system was used to measure motion of the shank, rearfoot, forefoot, and hallux segments and the vertical displacement of the navicular. Face validity and estimates of repeatability were determined. Motion patterns were calculated and comparisons were made between healthy subjects and patients with RA. Relationships between clinical impairment and abnormal motion were determined through inspection of individual RA cases. RESULTS: Across the motion variables, the within-day and between-day coefficient of multiple correlation values ranged from 0.677 to 0.982 for the healthy subjects and 0.830 to 0.981 for RA patients. Based on previous studies, motion parameters for the healthy subjects showed excellent face validity. In RA patients, there was reduced range of motion across all segments and all planes of motion, which was consistent with joint stiffness. In the RA patients, rearfoot motion was shifted towards eversion and external rotation and peak values for these variables were increased, on average, by 7 degrees and 11 degrees, respectively. Forefoot range of motion was reduced in all 3 planes (between 31% and 53%), but the maximum and minimum angles were comparable to normal. The navicular height, during full foot contact, was on average 3 mm lower in the RA patients in comparison to normal. The hallux was less extended in the RA subjects in comparison to normal (21 degrees vs 33 degrees) during the terminal stance phase. Individual cases showed abnormal patterns of motion consistent with their clinical impairments, especially those with predominant forefoot pain or pes planovalgus. CONCLUSION: In RA, multisegment foot models may provide a more complete description of foot motion abnormalities where pathology presents at multiple joints, leading to complex and varied patterns of impairment. This technique may be useful to evaluate functional changes in the foot and to help plan and assess logical, structurally based corrective interventions.

Manal K, Stanhope SJ   ”A novel method for displaying gait and clinical movement analysis data“ 2003 - Gait and Posture, Volume 20, Issue 2, Pages 222-226 Plotting kinematic and kinetic data of a patient’s movement patterns relative to normative values (i.e., mean and ±1 S.D.) is a common method used by clinicians to visually assess deviations and interpret the patient’s gait analysis data. This method of data interpretation is often time consuming and complex, especially when the process requires the inspection of a plethora of line graphs for numerous variables that are displayed across several report pages. In this paper we propose an alternate method for displaying movement pattern deviations relative to normative data by color-coding the magnitude and the direction of the deviation. An advantage of this approach is that a single page summary of all the deviation magnitudes can be displayed simultaneously, in a manner that is concise, visually effective and reduces complexity. The purpose of this paper is to describe the algorithmic development of the color-coding method.

Rudolf KS, Axe MJ, Buchanan TS, Scholz JP, Snyder-Mackler L   ”Dynamic stability in the anterior cruciate ligament deficient knee“ 2001 - Knee Surg. Sprots Traumatol, Arthrosc 9: 62-71 Some individuals can stabilize their knees following anterior cruciate ligament rupture even during activities involving cutting and pivoting (copers), others have instability with daily activities (non-copers). Movement and muscle activation patterns of 11 copers, ten non-copers and ten uninjured subjects were studied during walking and jogging. Results indicate that distinct gait adaptations appeared primarily in the non-copers. Copers used joint ranges of motion, moments and muscle activation patterns similar to uninjured subjects. Non-copers reduced their knee motion, and external knee flexion moments that correlated well with quadriceps strength. Non-copers also achieved peak hamstring activity later in the weight acceptance phase and used a strategy involving more generalized co-contraction. Both copers and non-copers had high levels of quadriceps femoris muscle activity. The reduced knee moment in the involved limbs of the non-copers did not represent “quadriceps avoidance” but rather represented a strategy of general co-contraction with a greater relative contribution from the hamstring muscles.

Kepple TM, Stanhope SJ   ”Move3D Software.“in Biomechanics and Neural Control of Posture and Movement” 2000 - (Winters and Crago Editors)

Gatev P, Thomas S, Kepple TM, & Hallett M   “Feedforward ankle strategy of balance during quiet stance in adults” 1999 - Journal of Physiology,514.3, 915-928 1. We studied quiet stance investigating strategies for maintaining balance. Normal subjects stood with natural stance and with feet together, with eyes open or closed. Kinematic, kinetic and EMG data were evaluated and cross-correlated. 2. Cross-correlation analysis revealed a high, positive, zero-phased correlation between anteroposterior motions of the centre of gravity (COG) and centre of pressure (COP), head and COG, and between linear motions of the shoulder and knee in both sagittal and frontal planes. There was a moderate, negative, zero-phased correlation between the anteroposterior motion of COP and ankle angular motion. 3. Narrow stance width increased ankle angular motion, hip angular motion, mediolateral sway of the COG, and the correlation between linear motions of the shoulder and knee in the frontal plane. Correlations between COG and COP and linear motions of the shoulder and knee in the sagittal plane were decreased. The correlation between the hip angular sway in the sagittal and frontal planes was dependent on interaction between support and vision. 4. Low, significant positive correlations with time lags of the maximum of cross-correlation of 250-300 ms were found between the EMG activity of the lateral gastrocnemius muscle and anteroposterior motions of the COG and COP during normal stance. Narrow stance width decreased both correlations whereas absence of vision increased the correlation with COP. 5. Ankle mechanisms dominate during normal stance especially in the sagittal plane. Narrow stance width decreased the role of the ankle and increased the role of hip mechanisms in the sagittal plane, while in the frontal plane both increased. 6. The modulation pattern of the lateral gastrocnemius muscle suggests a central program of control of the ankle joint stiffness working to predict the loading pattern.

Holden JP, Stanhope SJ.   “The Effect of Variation in Knee Center Location Estimates on Net Knee Joint Moments.” 1998 - Gait and Posture 7, 1-6

Kepple, TMSiegel, KL, , & Stanhope SJ   “Relative contributions of the lower extremity joint moments to forward progression and support during gait” 1997 - Gait and Posture, 6, 1-8

Kepple, T. Siegel , K., & Stanhope, S.   “The use of two foot-floor models to examine the role of the ankle plantar flexors in the forward acceleration of normal gait.” 1997 - Gait and Posture, 5, 172-173

Buczek FL, Kepple TM, Lohmann Siegel K., Stanhope SJ   “Effect of one, three, and six degree-of-freedom modeling upon joint powers at the normal knee.” 1994 - Proceedings of the Second World Congress on Biomechanics, 151

Buczek F., Siegel K., Kepple T., Stanhope S.   “Ground reaction force signal processing in joint power calculations.” 1991 - Proceedings of the Seventh Annual East Coast Gait Laboratory Conference

Kepple T.   “MOVE3D - Software for analyzing human motion.” 1991 - IEEE 1991 Future Directions Workshop, 106-109

Back to Top

Farana R, Irwin G, Jandacka D, Uchytil J, Mullineaux DR(2015)   “Elbow joint variability for different hand positions of the round off in gymnastics” Human Movement Science 39 (2015) 88–100 The aim of the present study was to conduct within-gymnast analyses of biological movement variability in impact forces, elbow joint kinematics and kinetics of expert gymnasts in the execution of the round-off with different hand positions. Six international level female gymnasts performed 10 trials of the round-off from a hurdle step to a back-handspring using two hand potions: parallel and Tshape. Two force plates were used to determine ground reaction forces. Eight infrared cameras were employed to collect the kinematic data automatically.Within gymnast variability was calculated using biological coefficient of variation (BCV) discretely for ground reaction force, kinematic and kinetic measures. Variability of the continuous data was quantified using coefficient of multiple correlations (CMC). Group BCV and CMC were calculated and T-test with effect size statistics determined differences between the variability of the two techniques examined in this study. Themajor observation was a higher level of biological variability in the elbow joint abduction angle and adduction moment of force in the T-shaped hand position. This finding may lead to a reduced repetitive abduction stress and thus protect the elbow joint from overload. Knowledge of the differences in biological variability can inform clinicians and practitioners with effective skill selection.

Farana, R., Jandacka, D., & Irwin, G. (2013). Influence of different hand positions on impact forces and elbow loading during the round off in gymnastics: A case study. Science of Gymnastics Journal, 5, 5–14.

Farana, R., Jandacka, D., Irwin, G. (2013)   “Influence of different hand positions on impact forces and elbow loading during the round off in gymnastics: A case study.” Science of Gymnastics Journal, 5, 5–14 The round-off is a fundamental gymnastics skill and a key movement in the development of elite female gymnasts. The aim of this study was to determine whether differences in hand position during the round-off may influence the ground reaction forces and elbow joint moments in female artistic gymnastics. One international level active female gymnast from the Czech Republic participated in this study. Two force plates were used to determine ground reaction forces. A motion-capture system consisting of eight infrared cameras were employed to collect the kinematic data. The gymnast performed 10 trials of a round-off from a hurdle step to back handspring with a “parallel” hand position and 10 trials with a “T” shape hand position. Effect size statistics were used to establish differences in means. In conclusion “T” position of the second hand reduces vertical and anterior-posterior ground reaction forces. Differences in joint elbow moments and elbow kinematics indicated that the “T” position may prevent elbow joint complex and reduces potential of elbow injuries.

Farana, R., Jandacka, D., Uchytil, J., Zahradnik, D., & Irwin, G. (2014)   “Musculoskeletal loading during the round-off in female gymnastics: The effect of hand position.” Sports Biomechanics, 13, 123–134. Chronic elbow injuries from tumbling in female gymnastics present a serious problem for performers. This research examined how the biomechanical characteristics of impact loading and elbow kinematics and kinetics change as a function of technique selection. Seven international-level female gymnasts performed 10 trials of the round-off from a hurdle step to flic-flac with 'parallel' and 'T-shape' hand positions. Synchronized kinematic (3D-automated motion analysis system; 247 Hz) and kinetic (two force plates; 1,235 Hz) data were collected for each trial. Wilcoxon non-parametric test and effect-size statistics determined differences between the hand positions examined in this study. Significant differences (p < 0.05) and large effect sizes (ES > 0.8) were observed for peak vertical ground reaction force (GRF), anterior-posterior GRF, resultant GRF, loading rates of these forces and elbow joint angles, and internal moments of force in sagittal, transverse, and frontal planes. In conclusion, the T-shape hand position reduces vertical, anterior-posterior, and resultant contact forces and has a decreased loading rate indicating a safer technique for the round-off. Significant differences observed in joint elbow moments highlighted that the T-shape position may prevent overloading of the joint complex and consequently reduce the potential for elbow injury.

Back to Top

Buffi JH1, Werner K, Kepple T, Murray WM. (2014)   “Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching.” Ann Biomed Eng. 2014 Oct 4. Baseball pitching imposes a dangerous valgus load on the elbow that puts the joint at severe risk for injury. The goal of this study was to develop a musculoskeletal modeling approach to enable evaluation of muscle-tendon contributions to mitigating elbow injury risk in pitching. We implemented a forward dynamic simulation framework that used a scaled biomechanical model to reproduce a pitching motion recorded from a high school pitcher. The medial elbow muscles generated substantial, protective, varus elbow moments in our simulations. For our subject, the triceps generated large varus moments at the time of peak valgus loading; varus moments generated by the flexor digitorum superficialis were larger, but occurred later in the motion. Increasing muscle-tendon force output, either by augmenting parameters associated with strength and power or by increasing activation levels, decreased the load on the ulnar collateral ligament. Published methods have not previously quantified the biomechanics of elbow muscles during pitching. This simulation study represents a critical advancement in the study of baseball pitching and highlights the utility of simulation techniques in the study of this difficult problem.

Back to Top

Soltania P, Figueiredo P, Fernandesa RJ, Vilas-Boasa JP. (2017)   “Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching.” Physiology & Behavior 181 (2017) 23–28. The effects of playing intensity and prior exergame and sport experience on the activation patterns of upper limb muscles during a swimming exergame were investigated. Surface electromyography of Biceps Brachii, Triceps Brachii, Latissimus Dorsi, Upper Trapezius, and Erector Spinae of twenty participants was recorded, and the game play was divided into normal and fast. Mean muscle activation, normalized to maximum voluntary isometric contraction (MVIC), ranged from 4.9 to 95.2%MVIC and differed between normal and fast swimming for all techniques (p < 0.05), except for Latissimus Dorsi during backstroke. After normalizing the %MVIC to playing velocity, selective behaviors were observed between muscles which were sufficient for pragmatic game play. Moreover, prior exergame and real sport experience did not have any effect on the muscle activation changes between normal and fast swimming. These behaviors are likely to happen when players understand the game mechanics, even after a short exposure. Such evaluation might help in adjusting the physical demands of sport exergames, for safe and meaningful experiences.
Back to Top

Susan J. Brown, Alan M. Nevill, Stuart A. Monk, Steve R. Otto, W. Scott Selbie & Eric S. Wallace   “Determination of the swing technique characteristics and performance outcome relationship in golf driving for low handicap female golfers.” 2008 - J Sports Sci. 2011 Oct 11. Previous studies on the kinematics of the golf swing have mainly focused on group analysis of male golfers of a wide ability range. In the present study, we investigated gross body kinematics using a novel method of analysis for golf research for a group of low handicap female golfers to provide an understanding of their swing mechanics in relation to performance. Data were collected for the drive swings of 16 golfers using a 12-camera three-dimensional motion capture system and a stereoscopic launch monitor. Analysis of covariance identified three covariates (increased pelvis–thorax differential at the top of the backswing, increased pelvis translation during the backswing, and a decrease in absolute backswing time) as determinants of the variance in clubhead speed (adjusted r 2 = 0.965, P < 0.05). A significant correlation was found between left-hand grip strength and clubhead speed (r = 0.54, P < 0.05) and between handicap and clubhead speed (r = −0.612, P < 0.05). Flexibility measures showed some correlation with clubhead speed; both sitting flexibility tests gave positive correlations (clockwise: r = 0.522, P < 0.05; counterclockwise: r = 0.711, P < 0.01). The results suggest that there is no common driver swing technique for optimal performance in low handicap female golfers, and therefore consideration should be given to individual swing characteristics in future studies.
Susan J. Brown, W. Scott Selbie & Eric S. Wallace   “The X-Factor: An evaluation of common methods used to analyse major inter-segment kinematics during the golf swing”. Journal of Sports Sciences.“ 2013 - J Sports Sci. (in press). A common biomechanical feature of a golf swing, described in various ways in the literature, is the interaction between the thorax and pelvis, often termed the X-Factor. There is no consistent method used within golf biomechanics literature however to calculate these segment interactions. The purpose of this study was to examine data calculated using three reported methods of the X-Factor in order to determine the similarity or otherwise of the data calculated using each method. A twelve camera three-dimensional motion capture system was used to capture the driver swings of 19 participants and a subject specific three-dimensional biomechanical model was created with the position and orientation of each model estimated using a global optimization algorithm. Comparison of the X-Factor methods showed significant differences for events during the swing (p<0.05). Data for each kinematic measure were derived as a times series for all three methods and regression analysis of these data showed that whilst one method could be successfully mapped to another, the mappings between methods are subject dependent (p<0.05). Findings suggest that a consistent methodology considering the X-Factor from a joint angle approach is most insightful in describing a golf swing.
Back to Top

Delextrat A, Goss-Sampson M.   ”Kinematic analysis of netball goal shooting: a comparison of junior and senior players.“ 2008 - J Sports Sci. 2010 Oct;28(12):1299-307. The aim of this study was to investigate the effect of playing experience on the kinematic characteristics of the goal shooting action in netball players. Six county-level junior and six senior goal shooters took part in the study. They were asked to perform eight shots at goal and were equipped with 33 retro-reflective markers fixed to anatomical landmarks for three-dimensional motion tracking. The shot was divided into three periods: start of throw, shooting action, and release. The following variables were determined for each period: position of the ball, joint angles, timings between actions, joint angular velocities, and ranges of motion. The main results showed a significant effect of playing experience, with senior shooters showing a shorter delay between the movements involved in the shooting action, a significant difference between the right and left elbow angles at the start of forearm extension, and greater extension of the left shoulder and greater flexion of the left elbow at release compared with junior shooters. These results might help justify some of the empirical observations made by coaches and direct them in their advice to players. In particular, recommendations to junior players should focus on the simultaneity of leg and arm actions and dissociation between the right and left arms during the shooting action .
Back to Top

Jones, P. L., Kerwin, D. G., Irwin, G. and Nokes, Leonard.   ”Three dimensional analysis of knee biomechanics when landing on natural turf and football turf.“ 2008 - ournal of Medical and Biological Engineering 29 (4) , pp. 184-188.. In 2004, Fédération Internationale de Football Association (FIFA) officially recognized artificial turf (football turf) as an appropriate playing surface for competitive football, although surface suitability remains relatively unknown and in particular, player testing of new surfaces is under-reported. The present study was designed with two aims: to examine knee joint angle precision of measurement and to investigate whether knee kinematics varied when landing from a jump on football turf (FT) and natural turf (NT). A series of static reference positions were compared for two series of repeated stationary measures and three dimensional (3D) knee joint angles used to assess intra- and inter-trial reliability. In addition, to eliminate marker placement variability, a single subject design was used to compare 20 jump landings following a heading movement performed on FT and 20 on NT in a randomized fashion. A single-step approach into a jump to head a stationary suspended football was followed by a single-leg landing on FT or NT and a two-step forward sprint. The turfs were mounted on a force plate (Kistler) and 3D kinematic data collected for all trials using an automated motion analysis system (CODA motion) utilizing cluster markers. Results showed reliability across reference positions and between most trials of ~1 . Observed differences highlighted the importance of initial static trial reference positions. For the turf landing trials, similar knee flexion/extension and internal/external rotation angles throughout the contact phase were seen, whilst differences occurred in knee adduction/abduction angles. Greater movement variability was demonstrated in all three knee joint angles under FT compared to NT. Such differences could be exaggerated during more dynamic football movements and may have performance and injury implications that warrant further investigation.
Back to Top

Lewis CL, Garibay EJ. (2014)   ”Effect of increased pushoff during gait on hip joint forces.“ J Biomech. 2014 Nov 12 Anterior acetabular labral tears and anterior hip pain may result from high anteriorly directed forces from the femur on the acetabulum. While providing more pushoff is known to decrease sagittal plane hip moments, it is unknown if this gait modification also decreases hip joint forces. The purpose of this study was to determine if increasing pushoff decreases hip joint forces. Nine healthy subjects walked on an instrumented force treadmill at 1.25m/s under two walking conditions. For the natural condition, subjects were instructed to walk as they normally would. For the increased pushoff condition, subjects were instructed to “push more with your foot when you walk”. We collected motion data of markers placed on the subjects׳ trunk and lower extremities to capture trunk and leg kinematics and ground reaction force data to determine joint moments. Data were processed in Visual3D to produce the inverse kinematics and model scaling files. In OpenSim, the generic gait model (Gait2392) was scaled to the subject, and hip joint forces were calculated for the femur on the acetabulum after computing the muscle activations necessary to reproduce the experimental data. The instruction to “push more with your foot when you walk” reduced the maximum hip flexion and extension moment compared to the natural condition. The average reduction in the hip joint forces were 12.5%, 3.2% and 9.6% in the anterior, superior and medial directions respectively and 2.3% for the net resultant force. Increasing pushoff may be an effective gait modification for people with anterior hip pain.

Back to Top

Gill N, Preece SJ, Young S, Bramah C.   ”Are the arms and head required to accurately estimate centre of mass motion during running?“ 2017 - Gait & Posture 51 (2017) 281–283 Accurate measurement of centre of mass (CoM) motion can provide valuable insight into the biomechanics of human running. However, full-body kinematic measurement protocols can be time consuming and difficult to implement. Therefore, this study was performed to understand whether CoM motion during running could be estimated from a model incorporating only lower extremity, pelvic and trunk segments. Full-body kinematic data was collected whilst (n = 12) participants ran on a treadmill at two speeds (3.1 and 3.9 ms�1). CoM trajectories from a full-body model (16-segments) were compared to those estimated from a reduced model (excluding the head and arms). The data showed that, provided an offset was included, it was possible to accurately estimate CoM trajectory in both the anterior-posterior and vertical direction, with root mean square errors of 5 mm in both directions and close matches in waveform similarity (r = 0.975-1.000). However, in the ML direction, there was a considerable difference in the CoM trajectories of the two models (r = 0.774–0.767). This finding suggests that a full-body model is required if CoM motions are to be measured in the ML direction. The mismatch between the reduced and full-body model highlights the important contribution of the arms to CoM motion in the ML direction. We suggest that this control strategy, of using the arms rather than the heavier trunk segments to generate CoM motion, may lead to less variability in CoM motion in the ML direction and subsequently less variability in step width during human running.

Willy RW, Manal KT, Witvrouw EE, Davis IS..   ”Are mechanics different between male and female runners with patellofemoral pain?.“ 2014 - Br J Sports Med. Apr;48(7):560-1 INTRODUCTION: Patellofemoral pain (PFP) has often been attributed to abnormal hip and knee mechanics in females. To date, there have been few investigations of the hip and knee mechanics of males with PFP. The purpose of this study was to compare the lower extremity mechanics and alignment of male runners with PFP with healthy male runners and female runners with PFP. We hypothesized that males with PFP would move with greater varus knee mechanics compared with male controls and compared with females with PFP. Furthermore, it was hypothesized that males with PFP would demonstrate greater varus alignment. METHODS: A gait and single-leg squat analysis was conducted on each group (18 runners per group). Measurement of each runner's tibial mechanical axis was also recorded. Motion data were processed using Visual 3D (C-Motion, Bethesda, MD). ANOVAs were used to analyze the data. RESULTS: Males with PFP ran and squatted in greater peak knee adduction and demonstrated greater peak knee external adduction moment compared with healthy male controls. In addition, males with PFP ran and squatted with less peak hip adduction and greater peak knee adduction compared with females with PFP. The static measure of mechanical axis of the tibial was not different between groups. However, a post hoc analysis revealed that males with PFP ran with greater peak tibial segmental adduction. CONCLUSION: Males with PFP demonstrated different mechanics during running and during a single-leg squat compared with females with PFP and with healthy males. Based upon the results of this study, therapies for PFP may need to be sex specific.

Alenezi F, Herrington L, Jones P, Jones R.   ”Relationships between lower limb biomechanics during single leg squat with running and cutting tasks: a preliminary investigation.“ 2014 - Br J Sports Med. Apr;48(7):560-1 BACKGROUND: The need to develop screening tests to find athletes who maybe predisposed to knee injuries is of prime importance in order to design individualised intervention programmes. Previous research has found 3D joint kinematics of the hip and knee during a single leg squat (SLS) to be related to those during jogging (Whatman et al., 2011). Thus, further investigation as a potential screening test is warranted. OBJECTIVE: To investigate the relationship between peak 3D kinematic variables during SLS with those occurring during running (RUN) and 90° cutting (CUT) tasks. DESIGN: A correlational study. SETTING: Undertaken in the human performance laboratory at the University of Salford. PARTICIPANTS: 15 recreational athletes, 7 males and 8 females, (age 25.2±5.1 years; height 1.6±7.38 m; and mass 67.6 ±10.93 kg) were recruited. INTERVENTIONS: A ten-camera motion analysis system (Qualisys) and a force platform (AMTI) were used to collect kinematic variables during SLS, RUN, & CUT tasks. Visual 3D (C-Motion, USA) was used to process all data. Pearson correlation coefficients were used to evaluate the association between 3D variables among the three tasks. MAIN OUTCOME MEASUREMENTS: Hip and knee joint angles. RESULT: SLS was strongly correlated to run in knee valgus and hip internal rotation (r=0.70 and 0.76, respectively), and showed moderate correlation with knee external rotation (0.42). SLS and CUT were moderate to strongly correlate to each other in knee valgus, knee flexion, and hip internal rotation (r=0.54, 0.69, and 0.54, respectively), and moderately in hip flexion (r=0.38). DISCUSSION: The findings of this study provide evidence that performance of SLS relates to performance of other tasks (running and cutting). In those individuals displaying poor motion (excessive angles) during SLS this is likely to be predictive of poor motion during running and cutting, so could negate the need for assessing individuals during these tasks.

McClay I, Manal K   ”Three-dimensional kinetic analysis of running: significance of secondary planes of motion.“ 1999 - Medicine and Science in Sports and Exercise 31:1629-1637 PURPOSE: The study of angular kinetic data provides important information regarding muscle function and may lend insight into the etiology of overuse injuries common to runners. These injuries are often due to deviations in the secondary planes of motion. However, little is known about the angular kinetics in these planes leaving no reference for comparison. METHODS: Therefore, three-dimensional kinematic and ground reaction force data were collected on 20 recreational runners with normal rearfoot mechanics. RESULTS: Findings suggest that sagittal plane kinetic data were similar to the two-dimensional studies reported in the literature. Sagittal plane data were least variable (CV: 9.3-11.0%) and comprised the largest percentage of positive or negative work done (80.2-88.8%) at both the rearfoot and knee joints. Transverse plane kinetics were most variable (CV: 68.5-151.9%) and constituted the smallest percentage of work done at both joints (0.7-7.4%). CONCLUSIONS: Although relatively smaller than the sagittal plane component, a substantial amount of positive work was done in the frontal plane at both joints (16.1-18.9%), suggesting that this component should not be ignored.

Ferber R, Noehren B, Hamill J, Davis IS.   ”Competitive female runners with a history of iliotibial band syndrome demonstrate atypical hip and knee kinematics.“ 2010 - J Orthop Sports Phys Ther. 2010 Feb;40(2):52-8. STUDY DESIGN: Cross-sectional experimental laboratory study. OBJECTIVE: To examine differences in running mechanics between runners who had previously sustained iliotibial band syndrome (ITBS) and runners with no knee-related running injuries. BACKGROUND: ITBS is the second leading cause of knee pain in runners and the most common cause of lateral knee pain. Despite its prevalence, few biomechanical studies have been conducted to better understand its aetiology. Because the iliotibial band has both femoral and tibial attachments, it is possible that atypical hip and foot mechanics could result in the development of ITBS. METHODS: The running mechanics of 35 females who had previously sustained ITBS were compared to 35 healthy age-matched and running distance-matched healthy females. Comparisons of hip, knee, and ankle 3-dimensional kinematics and internal moments during the stance phase of running gait were measured. RESULTS: The ITBS group exhibited significantly greater peak rearfoot invertor moment, peak knee internal rotation angle, and peak hip adduction angle compared to controls. No significant differences in peak rearfoot eversion angle, peak knee flexion angle, peak knee external rotator moment, or peak hip abductor moments were observed between groups. CONCLUSION: Females with a previous history of ITBS demonstrate a kinematic profile that is suggestive of increased stress on the iliotibial band. These results were generally similar to those reported for a prospective study conducted within the same laboratory environment. [PMID: 20118523 Reference]

Back to Top

Sinclair J, Richards J, Taylor PJ, Edmundson CJ, Brooks D, Hobbs SJ. (2012) 3-D kinematic comparison of treadmill and overground running. Sports Biomech. 2013 Sep;12(3):272-82. Studies investigating the mechanics of human movement are often conducted using the treadmill. The treadmill is an attractive device for the analysis of human locomotion. Studies comparing overground and treadmill running have analyzed discrete variables, however differences in excursion from footstrike to peak angle and range of motion during stance have yet to be examined. This study aimed to examine the 3-D kinematics of the lower extremities during overground and treadmill locomotion to determine the extent to which the two modalities differ. Twelve participants ran at 4.0m/s in both treadmill and overground conditions. 3-D angular kinematic parameters during the stance phase were collected using an eight camera motion analysis system. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes, then compared using paired t-tests. Of the parameters analyzed hip flexion at footstrike 12° hip range of motion 17°, peak hip flexion 12.7°, hip transverse plane range of motion 8° peak knee flexion 5° and peak ankle excursion range 6.6°, coronal plane ankle angle at toe-off 6.5° and peak ankle eversion 6.3° were found to be significantly different. These results lead to the conclusion that the mechanics of treadmill locomotion cannot be generalized to overground.

Altman AR, Reisman DS, Higginson JS, and Davis IS (2012)   ”A Kinematic Comparison of Split-belt and Single-belt Treadmill Walking and the Effects of Accommodation“ 2012 - Gait & Posture. 2012 February; 35(2): 287–291 INTRODUCTION: Instrumented treadmills are becoming increasingly more common in gait laboratories. Instrumented side-split treadmills allow the collection of forces under each foot during walking. However, there may be a tendency to increase the base of support when walking on these treadmills, influencing other frontal plane mechanics as well. Therefore, the purpose of this study was to examine the effect of walking on a side-split instrumented treadmill on base of gait and frontal plane kinematics of the lower extremity. METHODS: Twenty subjects walked on both a split and a single-belt treadmill. Base of gait and frontal plane kinematic angles and variability data were recorded. A one-way ANOVA was used to determine differences between the single and split-belt conditions at baseline and following a 10 minute accommodation on the split-belt. The relationships between the change in base of gait and change in each kinematic variable were also determined. RESULTS:On average, the base of gait was 3.7 cm wider on the split-belt treadmill with a 4 mm gap between belts. No significant differences were observed in the mean values of lower extremity kinematics or kinematic variability at baseline or following the 10 minute accommodation. However, the increase in base of gait was significantly related to a decrease in peak knee and hip adduction angles. CONCLUSION:The 4 mm gap between the treadmill belts significantly increased the mean base of gait in all subjects. This did not alter mean frontal plane kinematics. However, as base of gait increased, the tendency towards hip and knee abduction also increased.

Lee SJ, and Hidler J   ”Biomechanics of Overground Versus Treadmill Walking In Healthy Individuals.“ 2007 - Journal of Applied Physiology The goal of this study was to compare treadmill walking with overground walking in healthy subjects with no known gait disorders. Nineteen subjects were tested, where each subject walked on a split-belt instrumented treadmill as well as over a smooth, flat surface. Comparisons between walking conditions were made for temporal gait parameters such as step length and cadence, leg kinematics, joint moments and powers, and muscle activity. Overall, very few differences were found in temporal gait parameters or leg kinematics between treadmill and overground walking. Conversely, sagittal plane joint moments were found to be quite different, where during treadmill walking trials, subjects demonstrated less dorsiflexor moments, less knee extensor moments, and greater hip extensor moments. Joint powers in the sagittal plane were found to be similar at the ankle but quite different at the knee and hip joints. Differences in muscle activity were observed between the two walking modalities, particularly in the tibialis anterior throughout stance, and in the hamstrings, vastus medialis and adductor longus during swing. While differences were observed in muscle activation patterns, joint moments and joint powers between the two walking modalities, the overall patterns in these behaviors were quite similar. From a therapeutic perspective, this suggests that training individuals with neurological injuries on a treadmill appears to be justified.

Ine Van Caekenberghe, Veerle Segers, Peter Aerts, Patrick Willems and Dirk De Clercq   ”Joint kinematics and kinetics of overground accelerated running versus running on an accelerated treadmill.“ 2013 - J. R. Soc. Interface 2013 10, 20130222 Literature shows that running on an acceleratedmotorized treadmill is mechanically different from accelerated running overground. Overground, the subject has to enlarge the net anterior–posterior force impulse proportional to acceleration in order to overcome linearwhole body inertia,whereas on a treadmill, this force impulse remains zero, regardless of belt acceleration. Therefore, it can be expected that changes in kinematics and joint kinetics of the human body also are proportional to acceleration overground, whereas no changes according to belt acceleration are expected on a treadmill. This study documents kinematics and joint kinetics of accelerated running overground and running on an accelerated motorized treadmill belt for 10 young healthy subjects. When accelerating overground, groundreaction forces are characterized by less braking and more propulsion, generating a more forward-oriented ground reaction force vectorandamore forwardly inclined body comparedwith steady-state running. This change in body orientation as such is partly responsible for the changed force direction. Besides this,more pronounced hip andknee flexion at initial contact, a larger hip extension velocity, smaller knee flexion velocity and smaller initial plantarflexion velocity are associated with less braking. A larger knee extension and plantarflexion velocity result in larger propulsion. Altogether, during stance, joint moments are not significantly influenced by acceleration overground. Therefore, we suggest that the overall behaviour of the musculoskeletal system (in terms of kinematics and joint moments) during acceleration at a certain speed remains essentially identical to steady-state running at the same speed, yet acting in a different orientation. However, because acceleration implies extra mechanical work to increase the running speed, muscular effort done (in terms of power output) must be larger. This is confirmed by larger joint power generation at the level of the hip and lower power absorption at the knee as the result of subtle differences in joint velocity. On a treadmill, ground reaction forces are not influenced by acceleration and, compared with overground, virtually no kinesiological adaptations to an accelerating belt are observed. Consequently, adaptations to acceleration during running differ from treadmill to overground and should be studied in the condition of interest.

Ine Van Caekenberghe, Veerle Segers, Patrick Willems, Thierry Gosseye, Peter Aerts, and Dirk De Clercq   ”Mechanics of overground accelerated running vs. running on an accelerated treadmill.“ 2013 - Gait & Posture 38 (2013) 125–131 Unsteady state gait involving net accelerations has been studied overground and on a treadmill. Yet it has never been tested if and to what extent both set-ups are mechanically equal. This study documents the differences in ground reaction forces for accelerated running on an instrumented runway and running on an accelerating treadmill by building a theoretical framework which is experimentally put to the test. It is demonstrated that, in contrast to overground, no mean fore-after force impulse should be generated to follow an accelerating treadmill due to the absence of linear whole body acceleration. Accordingly, the adaptations in the braking phase (less braking) and propulsive phase (more propulsion) to accelerate overground are not present to follow an accelerating treadmill. It can be concluded that running on an accelerating treadmill is mechanically different from accelerated running overground.

Whatman C, Hing W, Hume P.   ”Are mechanics different between male and female runners with patellofemoral pain?.“ Phys Ther Sport. 2011 Feb;12(1):22-9 PURPOSE: To investigate the within-day and between-day reliability of 3D lower extremity kinematics during five lower extremity functional screening tests and to assess the association between these kinematics and those recorded during jogging. METHODS: Peak three-dimensional lower extremity kinematics were quantified in 25 uninjured participants during five lower extremity functional tests and jogging. A nine camera motion analysis system (Qualysis Medical AB, Sweden) was used to capture three trials of all tests. All functional tests were repeated by 10 participants one to two days later. Visual 3D (C-Motion Inc, USA) and Labview were used to process all data. Intraclass correlation coefficients (ICC) and typical errors (TE) were used to assess within- and between-day reliability of all variables. Pearson correlation coefficients were used to evaluate the association between peak joint kinematics during the functional tests and jogging. RESULTS: For the majority of kinematic variables the within-day reliability was excellent (ICC ≥ 0.92) and the between-day reliability was excellent to good (ICC ≥ 0.80). The correlation between kinematics of the functional tests and jogging was generally large to very large (r = 0.53 to 0.93). CONCLUSIONS: These results suggest these lower extremity functional screening tests should prove a useful clinical tool when assessing dynamic lower extremity alignment.

Back to Top

Brown AM, Zifchock RA, Hillstrom HJ.(2014)   ”The effects of limb dominance and fatigue on running biomechanics.“ Gait & Posture. 2014 Mar;39(3):915-9. PURPOSE: To establish whether lower extremity limb dominance has an effect on overground running mechanics. BACKGROUND: In attempts to resolve unilateral pathology, physical therapists often use the restoration of symmetry as a clinical milestone. While lower limb dominance has been shown to affect lower extremity mechanics during dynamic tasks such as jump landing, its effect on running gait is poorly understood. Further, despite the role of fatigue in running mechanics and injury, the interaction between fatigue and limb dominance has yet to be examined.METHODS: Three-dimensional kinematic and kinetic data were collected on 20 females during overground running. Data were collected prior-to and following a treadmill run to exertion. Dominant and non-dominant limb data were compared in the fresh-state using a paired t-test. A 2-way repeated-measures ANOVA was used to test for an interaction between fatigue and limb dominance. RESULTS: There were no significant differences between the kinematic or kinetic patterns of the dominant and non-dominant lower extremities during fresh-state overground running. Fatigue was not shown to interact with limb dominance. CONCLUSION: Limb dominance did not affect kinematic or kinetic side-to-side differences. Therefore, physical therapists can continue to use resolution of lower extremity symmetry as a goal of therapy without having to account for limb dominance. The lack of an interaction between fatigue and limb dominance indicates that the dominant and non-dominant limbs fatigue at a similar rate.

Back to Top

Neckel ND, Blonien N, Nichols D, Hidler J   ”Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern“ 2008 - J Neuroeng Rehabil. 2008; 5: 19. BACKGROUND: It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories. METHODS: A motion analysis system was used to track the kinematic patterns of the pelvis and legs of 10 chronic hemiparetic stroke subjects and 5 age matched controls as they walked in the Lokomat. The subject\\\\\\\'s legs were attached to the Lokomat using instrumented shank and thigh cuffs while instrumented footlifters were applied to the impaired foot of stroke subjects to aid with foot clearance during swing. With minimal body-weight support, subjects walked at 2.5 km/hr on an instrumented treadmill capable of measuring ground reaction forces. Through a custom inverse dynamics model, the ankle, knee, and hip joint torques were calculated in both the frontal and sagittal planes. A single factor ANOVA was used to investigate differences in joint torques between control, unimpaired, and impaired legs at various points in the gait cycle. RESULTS: While the kinematic patterns of the stroke subjects were quite similar to those of the control subjects, the kinetic patterns were very different. During stance phase, the unimpaired limb of stroke subjects produced greater hip extension and knee flexion torques than the control group. At pre-swing, stroke subjects inappropriately extended their impaired knee, while during swing they tended to abduct their impaired leg, both being typical abnormal torque synergy patterns common to stroke gait. CONCLUSION: Despite the Lokomat guiding stroke subjects through physiologically symmetric kinematic gait patterns, abnormal asymmetric joint torque patterns are still generated. These differences from the control group are characteristic of the hip hike and circumduction strategy employed by stroke subjects. Reference

Gordon KE and Ferris DP   ”Learning to walk with a robotic ankle exoskeleton“ 2007 - Journal of Biomechanics, 40:2636-2644 We used a lower limb robotic exoskeleton controlled by the wearer's muscle activity to study human locomotor adaptation to disrupted muscular coordination. Ten healthy subjects walked while wearing a pneumatically powered ankle exoskeleton on one limb that effectively increased plantar flexor strength of the soleus muscle. Soleus electromyography amplitude controlled plantar flexion assistance from the exoskeleton in real time. We hypothesized that subjects' gait kinematics would be initially distorted by the added exoskeleton power, but that subjects would reduce soleus muscle recruitment with practice to return to gait kinematics more similar to normal. We also examined the ability of subjects to recall their adapted motor pattern for exoskeleton walking by testing subjects on two separate sessions, 3 days apart. The mechanical power added by the exoskeleton greatly perturbed ankle joint movements at first, causing subjects to walk with significantly increased plantar flexion during stance. With practice, subjects reduced soleus recruitment by approximately 35% and learned to use the exoskeleton to perform almost exclusively positive work about the ankle. Subjects demonstrated the ability to retain the adapted locomotor pattern between testing sessions as evidenced by similar muscle activity, kinematic and kinetic patterns between the end of the first test day and the beginning of the second. These results demonstrate that robotic exoskeletons controlled by muscle activity could be useful tools for testing neural mechanisms of human locomotor adaptation.
Back to Top

Moore C, Nimbarte A, Rajulu S, Aghazadeh F. (2012) A study of the kinematics of ingress and egress of upright and recumbent seats. Work. 2012;41 Suppl 1:1316-22 Research has been done on the maximum reach and ingress/egress of upright seats. However, research on recumbent seats and comparisons between recumbent and upright seats is limited. By using an eight-camera Vicon motion capture system and C-motion Visual 3D modeling software, this research compared the ingress/egress joint kinematics and maximal planar reach of an upright seat with a recumbent seat. Mean range of motion and mean peak angle for each ingress/egress task were determined and the values for the upright seat were compared to the values for the recumbent seat. For each reach task, three extreme points were extracted and compared between the upright and recumbent seat. Seat orientation was found to have a statistically significant effect on the range of motion of several joints during the ingress/egress tasks, as well as one of the extreme points during the reaching tasks.
Back to Top

Whatman C, Hing W, Hume P. (2011) Kinematics during lower extremity functional screening tests--are they reliable and related to jogging? Phys Ther Sport. 2011 Feb;12(1):22-9. PURPOSE: To investigate the within-day and between-day reliability of 3D lower extremity kinematics during five lower extremity functional screening tests and to assess the association between these kinematics and those recorded during jogging. METHODS: Peak three-dimensional lower extremity kinematics were quantified in 25 uninjured participants during five lower extremity functional tests and jogging. A nine camera motion analysis system (Qualysis Medical AB, Sweden) was used to capture three trials of all tests. All functional tests were repeated by 10 participants one to two days later. Visual 3D (C-Motion Inc, USA) and Labview were used to process all data. Intraclass correlation coefficients (ICC) and typical errors (TE) were used to assess within- and between-day reliability of all variables. Pearson correlation coefficients were used to evaluate the association between peak joint kinematics during the functional tests and jogging. RESULTS: For the majority of kinematic variables the within-day reliability was excellent (ICC ≥ 0.92) and the between-day reliability was excellent to good (ICC ≥ 0.80). The correlation between kinematics of the functional tests and jogging was generally large to very large (r = 0.53 to 0.93). CONCLUSIONS: These results suggest these lower extremity functional screening tests should prove a useful clinical tool when assessing dynamic lower extremity alignment.
Back to Top

Blair S, Duthie G, Robertson S, Hopkins W, Ball K (2018) Concurrent validation of an inertial measurement system to quantify kicking biomechanics in four football codes Journal of Biomechanics 73 (2018) 24–32 Wearable inertial measurement systems (IMS) allow for three-dimensional analysis of human movements in a sport-specific setting. This study examined the concurrent validity of a IMS (Xsens MVN system) for measuring lower extremity and pelvis kinematics in comparison to a Vicon motion analysis system (MAS) during kicking. Thirty footballers from Australian football (n = 10), soccer (n = 10), rugby league and rugby union (n = 10) clubs completed 20 kicks across four conditions. Concurrent validity was assessed using a linear mixed-modelling approach, which allowed the partition of between and within-subject variance from the device measurement error. Results were expressed in raw and standardised units for assessments of differences in means and measurement error, and interpreted via non-clinical magnitude-based inferences. Trivial to small differences were found in linear velocities (foot and pelvis), angular velocities (knee, shank and thigh), sagittal joint (knee and hip) and segment angle (shank and pelvis) means (mean difference: 0.2–5.8%) between the IMS and MAS in Australian football, soccer and the rugby codes. Trivial to small measurement errors (from 0.1 to 5.8%) were found between the IMS and MAS in all kinematic parameters. The IMS demonstrated acceptable levels of concurrent validity compared to a MAS when measuring kicking biomechanics across the four football codes. Wearable IMS offers various benefits over MAS, such as, out-of-laboratory testing, larger measurementrange and quick data output, to help improve the ecological validity of biomechanical testing and the timing of feedback. The results advocate the use of IMS to quantify biomechanics of high-velocity movements in sport-specific settings.
Back to Top

Kepple, T. Siegel , K., & Stanhope, S. (1997) The use of two foot-floor models to examine the role of the ankle plantar flexors in the forward acceleration of normal gait. 1997 - Gait and Posture, 5, 172-173
João F, Veloso A, Cabral S, Moniz-Pereira V, Kepple T3. (2014) Synergistic interaction between ankle and knee during hopping revealed through induced acceleration analysis. Hum Mov Sci. 2014 Feb;33:312-20. The forces produced by the muscles can deliver energy to a target segment they are not attached to, by transferring this energy throughout the other segments in the chain. This is a synergistic way of functioning, which allows muscles to accelerate or decelerate segments in order to reach the target one. The purpose of this study was to characterize the contribution of each lower extremity joint to the vertical acceleration of the body's center of mass during a hopping exercise. To accomplish this, an induced acceleration analysis was performed using a model with eight segments. The results indicate that the strategies produced during a hopping exercise rely on the synergy between the knee and ankle joints, with most of the vertical acceleration being produced by the knee extensors, while the ankle plantar flexors act as stabilizers of the foot. This synergy between the ankle and the knee is perhaps a mechanism that allows the transfer of power from the knee muscles to the ground, and we believe that in this particular task the net action of the foot and ankle moments is to produce a stable foot with little overall acceleration.
Back to Top

MOVE3D was the precursor to Visual3D and was part of a technology transfer from the NIH executed formally in 2001, following 3 years of collaborative work, between C-Motion and the NIH. The original implementation of the NIH MOVE3D software was based on the work Tom Kepple did as part of his Master's degree at the University of Maryland.
Kepple, T (1989) Validation of a video-based, six degree-of-freedom mechanical analysis procedure for application to human movement. Unpublished Master's Thesis, University of Maryland, College Park, MD. Kepple TM, Stanhope SJ (2000) Move3D Software. in Biomechanics and Neural Control of Posture and Movement (Winters and Crago Editors)
Kepple T. (1991) MOVE3D - Software for analyzing human motion. IEEE 1991 Future The MOVE3D software was designed for use in the Department of Rehabilitation Medicine at the National Institutes of Health. It uses data obtained from a 3D motion measurement system to provide quantitative analysis of human musculoskeletal motion including three-dimensional graphical displays. MOVE3D aids in the understanding of human motion disorders, leading to recommendations and improvements in clinical interventions. The software is designed for clinical flexibility and can be used to study a variety of motion disorders. Currently patients with rheumatoid arthritis and post-polio syndrome are among the populations being studied. MOVE3D is also provided at no cost to motion analysis labs worldwide.
Antonsson EK (1982) A three-dimensional kinematic acquisition and intersegmental dynamic analysis system for human motion. Ph.D dissertation, Massachusetts Institute of Technology. NOTE: This was the seminal work that started Tom Kepple on the path of MOVE3D.
Kepple TM, Arnold AS, Stanhope SJ, Siegel KL (1994) Measurement of musculoskeletal motion from surface landmarks: A three-dimensional computer graphics approach. Journal of Biomechanics 27(3):365-371
Buczek FL, Kepple TM, Siegel KL, Stanhope SJ. (1994) Translational and Rotational Joint Power Terms in a Six Degree-of-Freedom Model of the Normal Ankle Complex. Journal of Biomechanics 27(12):1447-1457
Kepple T., Stanhope S. A (1989) A Video based, six degree of freedom approach for analyzing human motion. Proceedings of the Fifth Annual East Coast Gait Laboratories Conference
Kepple T., Stanhope S., Rich A. (1988) The presentation and evaluation of a video based, six degree-of-freedom approach for analyzing human motion” Proceedings of the Annual IEEE Engineering in Medicine and Biology Society
Back to Top

Hansen C, Honeine JL, Gibas D, Rezzoug N, Gorce P and Isableu B (2012) Low-cost motion capture systems in practice. Computer Methods in Biomechanics and Biomedical Engineering, Vol 15, No 51, 253-255 Optical motion capture technology is a very useful tool for collecting, analysing and quantifying human movements. Over the last decades, a variety of new systems have been developed with an enormous price range. The question arises of how well the so-called low-cost motion capture systems can perform and whether they are an option compared to high-end products. Natural Point has recently released their new 250Hz ‘low-cost’ motion capture system which raises the issue of the actual precision and reliability of their cameras compared to the well established Vicon motion capture system. Until the device has been validated as an accurate system, its use in research will remain uncertain. The aim of this study was thus to compare the two motion capture systems in standardised measurement conditions and furthermore to evaluate the accuracy of the Optitrack system.
Thewlis D, Bishop C, Daniell N, Paul G. (2012) Next Generation Low-Cost Motion Capture Systems Can Provide Comparable Spatial Accuracy to High-end Systems. J Appl Biomech. 2012 Jul 6 The objective quantification of three-dimensional kinematics during different functional and occupational tasks is now more in demand than ever. The introduction of new generation of low-cost passive motion capture systems from a number of manufacturers has made this technology accessible for teaching, clinical practice and in small/medium industry. Despite the attractive nature of these systems, their accuracy remains unproved in independent tests. We assessed static linear accuracy, dynamic linear accuracy and compared gait kinematics from a Vicon MX20 system to a Natural Point OptiTrack system. In all experiments data were sampled simultaneously. We identified both systems perform excellently in linear accuracy tests with absolute errors not exceeding 1%. In gait data there was again strong agreement between the two systems in sagittal and coronal plane kinematics. Transverse plane kinematics differed by up to 3° at the knee and hip, which we attributed to the impact of soft tissue artifact accelerations on the data. We suggest that low-cost systems are comparably accurate to their high-end competitors and offer a platform with accuracy acceptable in research for laboratories with a limited budget.
Back to Top