Journal of biomechanics最新文献

{"title":"A switched optimal control strategy in human balancing on a harmonically moving platform","authors":"Shaoyi Lu ,&nbsp;Jingtian Chen ,&nbsp;Huifang Li ,&nbsp;Li Zhang ,&nbsp;Tamas Insperger ,&nbsp;Gabor Stepan","doi":"10.1016/j.jbiomech.2025.112923","DOIUrl":"10.1016/j.jbiomech.2025.112923","url":null,"abstract":"<div><div>Postural balance is crucial for human daily activities, and understanding the neural-motor control mechanisms underlying balance performance is essential for improving diagnosis and intervention strategies for balance disorders. This study focuses on the human standing balance task on a harmonically moving platform with anterior–posterior translation, exploring the neural-motor control logic using a switched control strategy. It is hypothesized that humans switch between optimal energy gains and optimal decay gains to maintain balance in a safe and energy-efficient manner with the usage of optimal decay gains being closely related to balancing ability. A two-stage identification process is employed to determine switching time instances, starting with the adjoint method to estimate control gains and followed by the enumeration of gain switching instances. The proposed postural stability assessment indices, Control Strategy Ratio and Control Switch Frequency, offer clear physical interpretations and dynamic insights, demonstrating better consistency and sensitivity compared to some stabilometry parameters. These indices show potential for early diagnosis and intervention in balance disorders.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112923"},"PeriodicalIF":2.4,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting center of mass position in non-cyclic activities: The influence of acceleration, prediction horizon, and ground reaction forces","authors":"Mohsen Alizadeh Noghani,&nbsp;Edgar Bolívar-Nieto","doi":"10.1016/j.jbiomech.2025.112916","DOIUrl":"10.1016/j.jbiomech.2025.112916","url":null,"abstract":"<div><div>The whole-body center of mass (CoM) plays an important role in quantifying human movement. Prediction of future CoM trajectory, modeled as a point mass under influence of external forces, can be a surrogate for inferring intent. Given the current CoM position and velocity, predicting the future CoM position by forward integration requires a forecast of CoM accelerations during the prediction horizon. However, it is unclear how assumptions about the acceleration, prediction horizon length, and information from ground reaction forces (GRFs), which provide the instantaneous acceleration, affect the prediction. We study these factors by analyzing data of 10 healthy young adults performing 14 non-cyclic activities. We assume that the acceleration over a horizon will be (1) zero, (2) remain constant, or (3) converge to zero as a cubic trajectory, and perform predictions for horizons of 125 to 625 ms. We quantify the prediction performance by comparing the position error and accuracy of identifying the main direction of displacement against trajectories obtained from a whole-body marker set. For all the assumed accelerations profiles, position errors grow quadratically with horizon length (<span><math><mrow><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&gt;</mo><mn>0</mn><mo>.</mo><mn>930</mn></mrow></math></span>) while the accuracy of the predicted direction decreases linearly (<span><math><mrow><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&gt;</mo><mn>0</mn><mo>.</mo><mn>615</mn></mrow></math></span>). Post-hoc tests reveal that the constant and cubic profiles, which utilize the GRFs, outperform the zero-acceleration assumption in position error (<span><math><mrow><mi>p</mi><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>001</mn></mrow></math></span>, Cohen’s <span><math><mrow><mi>d</mi><mo>&gt;</mo><mn>3</mn><mo>.</mo><mn>23</mn></mrow></math></span>) and accuracy (<span><math><mrow><mi>p</mi><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>034</mn></mrow></math></span>, Cohen’s <span><math><mrow><mi>d</mi><mo>&gt;</mo><mn>1</mn><mo>.</mo><mn>44</mn></mrow></math></span>) at horizons of 125 and 250<!--> <span><math><mstyle><mi>m</mi><mi>s</mi></mstyle></math></span>. The results provide evidence for benefits of incorporating GRFs into predictions and point to 250<!--> <span><math><mstyle><mi>m</mi><mi>s</mi></mstyle></math></span> as a threshold for horizon length in predictive applications.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112916"},"PeriodicalIF":2.4,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144913353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and validation of a new simulator of running impacts","authors":"Robin Gassier ,&nbsp;Frédérique Hintzy ,&nbsp;Laurent Malisoux ,&nbsp;Christophe Hautier","doi":"10.1016/j.jbiomech.2025.112926","DOIUrl":"10.1016/j.jbiomech.2025.112926","url":null,"abstract":"<div><div>Understanding the mechanics of impacts during human locomotion is a current challenge for injury prevention, quantification of training loads and equipment design. The present study aimed to validate a new ergometer able to reproduce and measure impacts experienced during human locomotion, after a frequency-domain decomposition.</div><div>An ergometer was designed as a physical pendulum equipped with a weighted force plate released from a given angle and subjected to gravitational acceleration until it contacts, at its lowest point, the foot of the participant lying supine. The reliability of the generated impact properties was assessed on twenty participants using a test–retest procedure. The validity was evaluated on ten participants, by comparing ten individualized impacts produced by the ergometer to ten foot–ground impacts experienced while running at 10 km/h. A Discrete Fourier Transform was used to decompose the raw force signal into high-frequency (impact force) and low-frequency (active force) components. The signal was then recomposed into the time domain with inverse Fourier transform. Key variables (impact peak force and loading rate) were subsequently calculated.</div><div>Consistent intra- and inter-session reliability of these variables were obtained with acceptable coefficients of variation (from 15 % to 22 %). Bland-Altman analysis showed slight but significant higher impact peak forces during the retest, suggesting the need for a familiarization session. The impacts from the ergometer correlated at 0.98 with those measured during running, associated with low variation between them (&lt;10 %).</div><div>This ergometer provides a valid tool for reproducing locomotion-related impacts and studying their beneficial or deleterious effects on the human body.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112926"},"PeriodicalIF":2.4,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproducibility of quantitative greyscale and shear wave ultrasound measures of the supraspinatus tendon in individuals without shoulder pain or pathology","authors":"Nathan S Hogaboom ,&nbsp;Krina Vyas ,&nbsp;Peter Barrance","doi":"10.1016/j.jbiomech.2025.112925","DOIUrl":"10.1016/j.jbiomech.2025.112925","url":null,"abstract":"<div><div>Ultrasound and shear wave elastography (SWE) are powerful imaging modalities to assess biomarkers of tendon health. These include markers of collagen content and fiber alignment (echogenicity) and tissue stiffness (elasticity). Changes in these metrics could be useful when investigating tissue perturbations after intervention or activity. In the few studies that have investigated reliability of these measures in the supraspinatus tendon, technological limitations of the ultrasound devices imposed shear wave speed ceiling effects and likely biased their findings. The purpose of this study was to determine reliability statistics (intraclass correlation coefficients [ICCs], standard errors of measurement [SEMs], minimal detectable changes [MDCs]) of supraspinatus tendon elasticity and echogenicity among a cohort of ten young, pain-free individuals. Two investigators collected greyscale and SWE images of their supraspinatus tendons in longitudinal view. Each participant was imaged twice, separated by approximately one hour. Five participants returned four months later, and the imaging protocol was repeated. ICCs were “excellent” for echogenicity intra- and inter-rater reliabilities (≥91) at both time points. Elasticity was more varied – inter-rater ICCs ranged from “fair” (0.61) to “good” (0.89), whereas intra-rater ICCs were “good” to “excellent” across both timepoints (0.86–0.95). Large SEMs and wide ranges of agreement between raters suggest that while these measures are reliable, a single investigator should collect all images within the same subject to optimize measurement precision. Reported SEMs and MDCs can aid during interpretation of findings in future studies.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112925"},"PeriodicalIF":2.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of knee loads during activities of daily living using custom instrumented insoles and machine learning","authors":"Samantha J. Snyder ,&nbsp;Maliheh Fakhar ,&nbsp;Ross H. Miller ,&nbsp;Aniket Bera ,&nbsp;Jae Kun Shim","doi":"10.1016/j.jbiomech.2025.112921","DOIUrl":"10.1016/j.jbiomech.2025.112921","url":null,"abstract":"<div><div>Medial joint contact force, knee adduction moment, and knee flexion moment are key mechanical risk factors of knee osteoarthritis, yet calculating these knee loads traditionally requires time-intensive procedures with a gait laboratory. Integrating wearable technologies, such as instrumented insoles, with neural networks offers a promising avenue for rapid and accessible estimation of these variables in clinical environments. This study aimed to estimate knee loads during walking, running, sit-to-stand, and stand-to-sit activities using a recurrent neural network model trained on wearable sensor data. We hypothesized that the model would predict the key mechanical risk factors with strong correlation coefficients and low mean errors. Forty-seven participants performed all activities while instrumented insole and motion capture data were recorded. Reference knee adduction and flexion moments were calculated with inverse dynamics, and medial joint contact force was calculated with a reduction modeling approach. Activity-specific recurrent neural network models were trained using insole sensor data to predict knee loading variables. The models demonstrated strong predictive performance across all activities (0.88 &lt; r &lt; 0.98), except for sit-to-stand (r = 0.50) and stand-to-sit (r = 0.48) knee adduction moments, which showed moderate correlation coefficients. Mean absolute errors were moderate to low across variables. These findings highlight the feasibility of using a single instrumented insole combined with neural networks to estimate knee loads associated with osteoarthritis risk. This approach has the potential to enhance the accessibility of biomechanical assessments and support real-time biofeedback applications in both research and clinical settings.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112921"},"PeriodicalIF":2.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144917627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Same but different: a comparison of antigravity muscle moment outputs when measured by isokinetic dynamometer versus inverse dynamics","authors":"Juha-Pekka Kulmala","doi":"10.1016/j.jbiomech.2025.112918","DOIUrl":"10.1016/j.jbiomech.2025.112918","url":null,"abstract":"<div><div>Isokinetic dynamometers (IKD) and inverse dynamics (ID) approach are the two primary methods used to study muscle moment outputs during isolated and natural movements, respectively. However, it remains unclear whether these methods provide comparable moment values. This study, therefore, examined the maximum moment outputs of the main antigravity muscle groups as measured by IKD and ID methods. Maximum isometric moments were measured at matched joint angles from ankle plantarflexors, knee extensors, hip extensors, and hip abductors using a commercially available IKD and a force plate integrated apparatus, which enabled ID computation. On average, a 44 % (P = 0.002) greater ankle plantarflexor moment was obtained in ID than IKD condition, whereas the opposite – a 27 % (<em>P</em> = 0.037) greater extensor moment in IKD – was measured at the knee. No significant differences in moment outputs were found between the two methods for hip abductor and hip extensor muscles. Observation that IKD and ID methods produce significantly different moment outputs for ankle plantarflexor and knee extensor muscles should be considered when interpreting the results derived from these two methods.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112918"},"PeriodicalIF":2.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of sleeper and cross-body stretching on posterior shoulder capsule stiffness","authors":"Masahide Yagi ,&nbsp;Jun Umehara ,&nbsp;Taiga Noda ,&nbsp;Hiyu Mukai ,&nbsp;Noriaki Ichihashi","doi":"10.1016/j.jbiomech.2025.112922","DOIUrl":"10.1016/j.jbiomech.2025.112922","url":null,"abstract":"<div><div>We aimed to determine whether sleeper (SL) and cross-body (CB) stretching immediately reduce posterior capsule stiffness and to examine their differential effects on the middle and inferior posterior capsular regions. The nondominant shoulders of 15 healthy young adult men were included in this crossover study. Shear moduli of the middle and inferior posterior capsules were measured using shear-wave elastography before and 5 min after stretching. A repeated-measures two-way analysis of variance (stretching method × time) was performed for the shear modulus of each capsule, followed by post hoc Wilcoxon signed-rank tests. The significance level was set at 5 %. To assess whether the observed changes exceeded measurement error, minimal detectable change (MDC) values were calculated from pilot data. For the middle posterior capsule, a significant stretching method × time interaction was observed, and the shear modulus decreased significantly after SL stretching. All participants exhibited a decrease in shear modulus, with five exceeding the MDC. For the inferior posterior capsule, only a main effect of time was noted, indicating a significant decrease in shear modulus after both SL and CB stretching. All participants exhibited a decrease in shear modulus, with six surpassing the MDC in both SL and CB stretching. These findings indicate that SL stretching decreases the shear modulus of both regions of the posterior capsule, whereas CB stretching reduces the shear modulus of only the inferior region. These findings allow clinicians to select the most appropriate stretching techniques for the middle and inferior posterior capsules.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112922"},"PeriodicalIF":2.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gait classification in individuals with unilateral transfemoral amputation using random forest and k-means clustering","authors":"Yufan He ,&nbsp;Mingyu Hu ,&nbsp;Alpha C.H. Lai ,&nbsp;Mark W.P. Koh ,&nbsp;Hiroaki Hobara ,&nbsp;Fan Gao ,&nbsp;Toshiki Kobayashi","doi":"10.1016/j.jbiomech.2025.112920","DOIUrl":"10.1016/j.jbiomech.2025.112920","url":null,"abstract":"<div><div>Cluster analysis has been recently applied to categorize gait patterns in individuals with unilateral transfemoral amputation (uTFA). However, conventional clustering methods largely rely on experiential knowledge of gait analysis, lacking a scientific foundation for feature selection. The aim of this study was to investigate if gait patterns could be classified using random forest and k-means clustering in individuals with uTFA. Spatiotemporal data and vertical ground reaction force (vGRF) were collected using an instrumented treadmill from twelve individuals with uTFA and twelve age-matched non-disabled individuals participated. Absolute symmetry index (ASI) was obtained and normalized. These parameters served as inputs for a random forest model to assess their importance. K-means clustering was applied to determine the optimal number of clusters according to Silhouette Score and the Elbow Method. Differences in demographic, spatiotemporal, and ASI parameters among clusters were assessed using One-way ANOVA and independent-sample Kruskal-Wallis tests. Random forest model revealed that swing phase and single limb support duration time symmetries were most significant for distinguishing individuals with uTFA from non-disabled. The k-means identified three distinct clusters: cluster 1 exhibited the lowest symmetry with the shortest prosthetic single limb support duration; cluster 2 displayed the highest symmetry with the longest prosthetic single limb support duration and intact step length; cluster 3 demonstrated moderate symmetry with the highest cadence. This study highlights that customized rehabilitation targeting specific gait patterns—such as strengthening muscles to increase single-limb support and step length, and modulating cadence—could enhance gait performance in individuals with uTFA.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112920"},"PeriodicalIF":2.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calculation of a force effect from muscle action to a quaternion-based musculoskeletal model","authors":"Ondrej Zoufaly ,&nbsp;Edward K. Chadwick ,&nbsp;Dimitra Blana ,&nbsp;Matej Daniel","doi":"10.1016/j.jbiomech.2025.112904","DOIUrl":"10.1016/j.jbiomech.2025.112904","url":null,"abstract":"<div><div>Euler and Cardan angles representation in biomechanical analysis allows straightforward description of joint rotations. However, application of Euler or Cardan angles can be problematic due to a singularity called gimbal lock. Quaternions offer an alternative way to describe rotation that avoids this problem, but they are not commonly used in biomechanics as they are complex and not inherently intuitive, specifically in dynamic models actuated by muscles. This study introduces a mathematical framework for describing muscle actions in dynamic quaternion-based musculoskeletal simulations. The proposed method estimates muscle torques in a quaternion-based musculoskeletal model. Its application is shown in a three-dimensional double-pendulum system actuated by muscle elements. Furthermore, the transformation of muscle moment arms obtained from muscle paths based on Euler or Cardan angles into a quaternion-based description is presented. The proposed method is advantageous for dynamic modeling of musculoskeletal models with complex kinematics and joints with large ranges of motion like the shoulder joint.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112904"},"PeriodicalIF":2.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reducing flight time during running decreases tibial-fibular strains in male runners: a finite element analysis","authors":"Arash Khassetarash ,&nbsp;Benno M. Nigg ,&nbsp;W. Brent Edwards","doi":"10.1016/j.jbiomech.2025.112917","DOIUrl":"10.1016/j.jbiomech.2025.112917","url":null,"abstract":"<div><div>Reducing strains within the tibia and fibula during running may reduce the risk of stress fractures. We examined the effect of reduced flight time during running (i.e., grounded running) on finite-element predicted bone strains within the tibia-fibula complex. Nine physically active males ran on an instrumented treadmill at 2.2 m/s using a preferred and reduced flight time technique in a randomized order. Three-dimensional force and motion capture data were recorded during running and a computed tomography image was subsequently acquired for the participant’s left leg. An inverse-dynamics-based musculoskeletal modeling workflow was used to calculate bone-on-bone contact and muscle forces during the stance phase of running. These forces served as inputs to a participant-specific finite-element model to estimate peak bone strains and strained volume (i.e., the volume of bone experiencing strains above a specific threshold) within the tibia-fibula complex. Guided attempts to reduce flight time was successful with an 18 ms (95 % CI: 12 ms, 25 ms; p &lt; 0.001) reduction in flight time. Reducing flight time was associated with significant reductions in peak tibial/fibular strains (17 % lower; 95 % CI: −7.1 %, −25.0 %; p = 0.002) and strained volume (35 % lower; 95 % CI: −13.57 %, −50.87 %; p = 0.007). We conclude that guided attempts to reduce flight time significantly reduces strains in the tibia and fibula during treadmill running at a fixed speed. These results suggest that grounded running may be a viable technique to reduce musculoskeletal loading and stress fracture risk, particularly in slow runners and those runners coming back from injury.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"191 ","pages":"Article 112917"},"PeriodicalIF":2.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}