Journal of biomechanics最新文献

{"title":"The influence of lower limb kinematic characteristics in stroke patients on gait speed mediated by paretic side propulsive force","authors":"Haruna Ukigai ,&nbsp;Yuichiro Hosoi ,&nbsp;Takayuki Kamimoto ,&nbsp;Junsuke Ito ,&nbsp;Arisa Kawabata ,&nbsp;Kohsuke Okada ,&nbsp;Kohshiro Haruyama ,&nbsp;Tetsuya Tsuji ,&nbsp;Michiyuki Kawakami","doi":"10.1016/j.jbiomech.2026.113220","DOIUrl":"10.1016/j.jbiomech.2026.113220","url":null,"abstract":"<div><div>The relationships among gait speed, paretic side propulsive force (PPF), and kinematic characteristics in stroke patients remain unclear. This study retrospectively analyzed data from 109 post-stroke patients to identify kinematic characteristics influencing gait speed mediated by PPF. Motion capture system was used for measuring ground walking, and hip, knee, and ankle joint angle during stance phase of paretic side were extracted. The joint angle data were classified into four phases (the initial double-support (Phase 1), the first and second 50% of the single-leg stance (Phase 2, Phase 3), the second double-support (Phase 4)), and average angle of the time series for each phase was calculated (kinematic variables). Comfortable gait speed (CGS) and PPF were also averaged. Statistical analysis first performed correlation analysis between CGS, PPF and kinematic variables. Next, mediation analysis was conducted using kinematic variables as independent variables, CGS as dependent variable, and PPF as mediating variable. Correlation analysis revealed that the kinematic variables of hip and knee joints in all phases, and ankle joint in Phase 3, showed significant correlations with CGS and PPF. For mediation analysis, the mediation model with only indirect effects significant was established for the following variables: hip extension (Total Effect (TE) =  − 0.007, p = 0.018), knee flexion (TE = 0.010, p &lt; 0.01), and ankle dorsiflexion (TE = 0.013, p &lt; 0.01) in Phases 3 and hip extension in Phase 4 (TE =  − 0.011, p &lt; 0.01). These four kinematic variables were each found to influence gait speed mediated by PPF. In gait intervention, focusing on these joint movements during mid-to-late stance phase is important.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"199 ","pages":"Article 113220"},"PeriodicalIF":2.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147271089","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":"Corrigendum to “The impact of backpack load on adolescent stair descent safety and injury risk” [J. Biomech. 166 (2024) 112029]","authors":"Zijun Lu,&nbsp;Chuangui Mao,&nbsp;Yuanyuan Tan,&nbsp;Tao Liu,&nbsp;Xinglu Li,&nbsp;Zhengao Li,&nbsp;Wenfei Zhu,&nbsp;Yuliang Sun","doi":"10.1016/j.jbiomech.2026.113215","DOIUrl":"10.1016/j.jbiomech.2026.113215","url":null,"abstract":"<div><div>This study investigates the impact of increasing backpack load on the gait of adolescents during stair descent. Sixteen healthy male students (age = 12.9 ± 0.6 years) were required to descend the stairs in 4 loaded conditions. The kinematic, kinetic, and EMG data were collected synchronously and gait parameters, especially indicators of balance control, were analyzed. The posterior tilt angles (COM-COP IA in the sagittal plane) (0%–42%, 48%–53%, 58%–91%, p &lt; 0.01), trunk anterior tilt angles (9–33%, 51–65%, p &lt; 0.01), and CV of stride length (p &lt; 0.01) increased with the backpack load. The COM-Step edge separation decreased with the increased backload (p &lt; 0.01). In addition, the hip flexion torque (25–40%, 45–51%, p &lt; 0.01), the rectus femoris activation, and the hip stiffness increased significantly as the load up to 15% Body Weight (BW)and 20% BW. The increasing backpack load may affect adolescent’s stair descent gait. Especially as the load was up to 15% BW, the adolescents’ bodies tended to tilt backwards relative to the support foot during the single stance phase. They may activate the hip flexors and tilt forward the trunk to recover from the balance perturbation, which was associated with increased hip flexion torques. This adjustment was more pronounced with the increasing backpack load. However, excessive forward flexion may increase the risk of forward falls. The boundaries of adjustment need further research in the future. Findings from this study provide baseline information on the intrinsic mechanisms of balance control during stair descent.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"199 ","pages":"Article 113215"},"PeriodicalIF":2.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147283903","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":"Mesenchymal stem cells differentiate dynamic from static load through variable regulation of the Hippo pathway","authors":"Zhihui Xie ,&nbsp;Buer Sen ,&nbsp;Nina Nikitina ,&nbsp;Sean Howard ,&nbsp;Maya Styner ,&nbsp;Clinton Rubin ,&nbsp;Gunes Uzer ,&nbsp;Janet Rubin","doi":"10.1016/j.jbiomech.2026.113228","DOIUrl":"10.1016/j.jbiomech.2026.113228","url":null,"abstract":"<div><div>The mechanical environment of a cell, which profoundly influences cell behaviors, includes loading parameters such as magnitude, rate cycle number and duration. Time-varying, or dynamic, levels of load are generally associated with anabolic responses, while time invariant, or static, forces often increase catabolic pathophysiology. How cells differentiate between static and dynamic loading parameters is unclear. In mesenchymal stem cells (MSC), we found that static strain (SS) increased nuclear YAP at 3 h, whereas 200 cycles of dynamic strain (DS) did not. Differences in nuclear YAP were directed by phosphorylation of Hippo enzymes: SS promoted association of PP2Ac dephosphorylase with nuclear MST1/2. In contrast, DS activated Hippo signaling with phosphorylation of MST1/2 and YAP. Actin remodeling was differentially affected by DS and SS: DS generated thicker fibers with greater cross-sectional area and enhanced parallel alignment. In contrast, static strain reinforced the existing isotropic actin network by increasing fiber density and focal adhesion count. DS induced actin remodeling was associated with phosphorylation of both LATS1/2 and AMOT, which binds both actin and nuclear MST1/2. When LATS1/2 was inhibited, or AMOT was knocked down, nuclear PP2Ac increased and YAP was dephosphorylated. This suggests that DS induced actin remodeling provokes release of phosphorylated AMOT from actin binding sites, while SS induced actin reinforcement sequesters AMOT. In sum, our data shows that MSC are equipped to differentiate between load components, resulting in nuanced mechanical effects on the Hippo pathway.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"199 ","pages":"Article 113228"},"PeriodicalIF":2.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147306224","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 infraglottal implantation on voice production in type I thyroplasty: a computational study","authors":"Weili Jiang ,&nbsp;Charles Farbos de Luzan ,&nbsp;Liran Oren ,&nbsp;Ephraim Gutmark ,&nbsp;Xudong Zheng ,&nbsp;Qian Xue","doi":"10.1016/j.jbiomech.2026.113234","DOIUrl":"10.1016/j.jbiomech.2026.113234","url":null,"abstract":"<div><div>Type I thyroplasty (TT1) is one of the primary phonosurgical interventions for unilateral vocal fold paralysis. This study investigated the effects of infraglottal implant placement in TT1 on voice production using numerical simulations. The laryngeal and implant geometries were reconstructed from computed tomography scan of a canine larynx with a hand-carved Silastic implant. Fluid–structure interaction simulations, coupling the continuum finite element vocal fold and implant models with a one-dimensional Bernoulli-based glottal flow model, were conducted to evaluate vocal fold vibration across a range of implant stiffnesses, insertion depths, and vertical positions. Effects of implant parameters on pre-phonatory shape and stiffness, glottal flow and vocal fold dynamics and acoustic outcome have been analyzed. The results revealed that infraglottal implants can enhance both sound pressure level (SPL) and vocal efficiency (VE) when the insertion depth exceeds a certain threshold. The observed enhancement in SPL and VE was attributed to an increased vertical stiffness gradient in the vocal folds induced by the inferior implant, which leads to greater force asymmetry between vocal folds opening and closing, thereby promoting more effective energy transfer from the glottal airflow to the vocal folds. The result is larger vocal fold vibrations, which leads to a larger SPL and may also contribute to the improved VE. The current simulation is based on the simulation of one single canine larynx. Future studies incorporating more subjects would help to generalize the current findings.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"199 ","pages":"Article 113234"},"PeriodicalIF":2.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147326169","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":"Differential mechanical behaviour of superficial and deep aponeurosis and tendon during in situ cyclic contractions of rabbit medial gastrocnemius muscle","authors":"Stephanie A. Ross,&nbsp;Christine Waters-Banker,&nbsp;Andrew Sawatsky,&nbsp;Timothy R. Leonard,&nbsp;Walter Herzog","doi":"10.1016/j.jbiomech.2026.113212","DOIUrl":"10.1016/j.jbiomech.2026.113212","url":null,"abstract":"<div><div>Aponeuroses are sheet-like extensions of tendon that transmit forces from muscle fascicles but experience more complex and heterogeneous loading than tendons. Despite this, most muscle models treat tendon and aponeurosis as a single, uniform elastic element in series with muscle. In this study, we examined strains of the superficial and deep aponeurosis and distal tendon of the rabbit medial gastrocnemius <em>in situ</em> under dynamic, physiologically relevant cyclic contractions. We found that, unlike tendon, aponeurosis did not exhibit strain patterns proportional to muscle force. Instead, both aponeuroses showed peak strain early in the activation phase and remained largely constant length during subsequent muscle shortening or lengthening, despite changes in force and belly length. These patterns were absent during passive cycles, indicating context-dependent behaviour of the aponeuroses. The superficial aponeurosis showed considerable variability in strain patterns across animals, particularly during active shortening, consistent with previous <em>in vivo</em> measures. Our findings challenge the assumption that aponeurosis and tendon function as a single series elastic element. Instead, aponeurosis exhibits distinct mechanical behaviour due to its complex structure and loading from the underlying muscle tissue. These results emphasize the need for muscle models that represent aponeurosis and tendon as separate structures, reflecting their unique mechanical behaviours and roles during contraction.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"199 ","pages":"Article 113212"},"PeriodicalIF":2.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146258032","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":"Simulated gait training improves joint loading symmetry in unilateral transfemoral bone-anchored limb users","authors":"Nicholas W. Vandenberg ,&nbsp;Benjamin B. Wheatley ,&nbsp;R. Dana Carpenter ,&nbsp;Cory L. Christiansen ,&nbsp;Jason W. Stoneback ,&nbsp;Brecca M.M. Gaffney","doi":"10.1016/j.jbiomech.2026.113199","DOIUrl":"10.1016/j.jbiomech.2026.113199","url":null,"abstract":"<div><div>Bone-anchored limbs (BALs) are promising alternatives for addressing socket-related pathologies, but evidence suggests movement and joint loading asymmetries persist 12-months following transfemoral BAL implantation. Gait training targeting biomechanical symmetry is common in rehabilitation for people with transfemoral amputation. However, it is unknown if people with transfemoral BALs can achieve symmetrical gait due to absent anatomical structures. Our objective was to determine if gait symmetry is feasible in transfemoral BAL users and investigate the biomechanical effects of enforcing symmetry using optimal control and musculoskeletal modeling. Using OpenSim Moco, we simulated gait training interventions for 11 transfemoral BAL users by predicting a target gait pattern (assuming intact musculoskeletal systems) that were then tracked using subject-specific BAL models. Movement patterns after simulated training were evaluated to assess changes in symmetry using magnitude and phase difference metrics and Pearson correlation coefficients. Joint loading was compared to baseline values temporally (using statistical parametric mapping) and discretely (joint reaction force (JRF) impulses, stance time, and respective symmetries). Trained solutions were more in-phase and highly correlated with non-amputated kinematics and across limbs, demonstrating that the clinical objective was achievable. Amputated limb resultant hip JRF increased in loading response and terminal stance (<em>p</em> = 0.020 and <em>p</em> = 0.004, respectively), resulting in improved symmetry during terminal stance (<em>p</em> = 0.003) following simulated training. Joint loading impulses were also increased in the amputated limb (<em>p</em> &lt; 0.001), with little change in the intact limb (<em>p</em> = 0.337), resulting in improved joint loading-symmetry (<em>p</em> = 0.001). These results demonstrate movement symmetry is achievable without deleterious joint loading effects in bilateral limbs.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"198 ","pages":"Article 113199"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146172165","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":"A single-rigid-body model for triple jump","authors":"Hiroki Okubo ,&nbsp;Mont Hubbard","doi":"10.1016/j.jbiomech.2025.112989","DOIUrl":"10.1016/j.jbiomech.2025.112989","url":null,"abstract":"<div><div>A single-rigid-body model is used to approximately calculate total triple jump distance and phase ratios, given phase takeoff angles and last stride takeoff velocity. Each of the three phases contains two segments: support from touchdown to takeoff, and gravitational flight with air drag. Translational and rotational equations of motion including track reaction forces and moments describe center-of-mass translation and rotation during support segments. In each support, human muscular inputs shape the track reaction force. Two very simple assumptions are made about the orientation of the body during flight, namely that the body remains vertical and takes off with zero pitching angular momentum. Evaluation of the vertical and horizontal support impulses reveals takeoff angles as control variables and that the essential optimization problem can be viewed as choosing sequentially three takeoff angles to maximize total distance. To assess validity, numerical results are compared with actual competition measurements.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"198 ","pages":"Article 112989"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147402694","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":"Optimum takeoff angles for triple jump","authors":"Hiroki Okubo ,&nbsp;Mont Hubbard","doi":"10.1016/j.jbiomech.2025.113011","DOIUrl":"10.1016/j.jbiomech.2025.113011","url":null,"abstract":"<div><div>An approximate single-rigid-body (SRB) model for triple jump (Okubo and Hubbard, 2025) is used numerically to investigate total distance in terms of run-up speed and hop, step and jump takeoff angles. At each speed a single optimal combination of takeoff angles produces maximum total distance. Using the model with previously measured realistic elite takeoff angles confirms roughly linear correlation between loss of horizontal velocity and gain in vertical velocity during support. It is striking that the simple assumptions in the SRB model (regarding body orientation and lack of pitching angular velocity in flight) are able to account, even loosely, for the velocity conversion process, Yu and Hay, (1996). As total distance increases, the likelihood of a jump-dominated optimal strategy also increases with these features: horizontal speed is maintained in hop and step; jump and step takeoff angles are the largest and smallest, respectively, of the three; step distance is shortest. In the speed range 10.0–10.5 m/s the optimum jump-dominated technique is always best, but only marginally (almost too marginally to notice). The model evaluates importance of run-up speed which mostly affects takeoff speeds, but has almost no effect on optimal takeoff angles. Although the model is deterministic, it can be used with random initial conditions to understand uncertainty effects in jumper execution. Use of the model shows that phase ratios are not controllable parameters but only results.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"198 ","pages":"Article 113011"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145354891","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":"Corrigendum to “Markerless motion capture for running: validity and reliability of whole-body, joint, and muscle kinematics” [J. Biomech. 195 (2026) 113133]","authors":"Jasper Verheul,&nbsp;Owain Hughes,&nbsp;Luke Hitchens,&nbsp;Toby Atherton,&nbsp;Toby Sauter,&nbsp;Amir Radwan,&nbsp;Elis Pryse,&nbsp;Alice Mitchell,&nbsp;Sophie Burton","doi":"10.1016/j.jbiomech.2026.113195","DOIUrl":"10.1016/j.jbiomech.2026.113195","url":null,"abstract":"","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"198 ","pages":"Article 113195"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146125185","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":"Exercise-induced fatigue effects on postural control in young adults: A systematic review and meta-analysis","authors":"Tiago Penedo ,&nbsp;Nicolas Vuillerme ,&nbsp;Matthias Chardon ,&nbsp;Paulo Cezar Rocha dos Santos ,&nbsp;Fabio Augusto Barbieri","doi":"10.1016/j.jbiomech.2026.113189","DOIUrl":"10.1016/j.jbiomech.2026.113189","url":null,"abstract":"<div><div>Exercise-induced fatigue disrupts the neuromuscular system, contributing to postural instability in young adults. The systematic investigation into the impact of exercise-induced fatigue on postural control, particularly in acute (immediate), short- (minutes after), and long-lasting contexts (hours or days later), is relevant to understanding the limits of human postural adaptation to fatigue. This systematic review and meta-analysis aimed to assess and quantify how exercise-induced fatigue alters upright posture and the duration of these effects on healthy young adults’ postural control. Following PRISMA guidelines, the search was conducted in PubMed, Web of Science, SCOPUS, SPORTDiscus, and CINAHL from inception to October 2025. Random-effects meta-analyses examined the acute effects of exercise-induced fatigue on center of pressure (CoP) parameters. Forty-one studies (from 1997 to 2025) were included, involving 702 young adults and a diverse array of exercise protocols and postural tasks. Meta-analyses indicated that exercise-induced fatigue significantly increased CoP outcomes, with moderate to large overall effects (SMDs = 0.41–3.10, p &lt; 0.05) regardless of visual condition (eyes open or closed). Considerable heterogeneity was observed due to methodological discrepancies across studies. In conclusion, regardless of visual condition, exercise-induced fatigue impairs postural control in young healthy adults, increasing body sway and decreasing muscle activity acutely; the body sway remains increased for a short- and long-lasting stages.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"198 ","pages":"Article 113189"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116340","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}