Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Effect of a Post-Activation Potentiation-Based Plyometric Warm-Up on Hand and Pelvis Linear Velocity During the Gyaku-Zuki Punch: A Quasi-Experimental Study 372 393 FA Sina Najafpoor Department of Sports Biomechanics, Faculty of Physical Education and Sport Sciences, Kharazmi University, Tehran, Iran. Hamed Fadaei Department of Sports Biomechanics, Faculty of Physical Education and Sport Sciences, Kharazmi University, Tehran, Iran. Hakime Adigozali Department of Physiotherapy, Faculty of Rehabilitation Sciences, Tabriz University of Medical Sciences, Tabriz, Iran. Amir Ghiami Rad Department of Motor Behavior, Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran. Objective Post-activation potentiation (PAP) warm-up has been proposed as an effective strategy to enhance athletic performance and muscular power. This study aimed to investigate the effects of a plyometric-based PAP warm-up on hand and pelvis linear velocity during the execution of a gyaku-zuki punch in male karate athletes. Methods In this quasi-experimental study, 19 male karate athletes completed two warm-up protocols, including a standard warm-up and a standard warm-up combined with a PAP protocol consisting of tuck jumps. Kinematic data were collected using a three-dimensional motion capture system. The assessed variables included maximum and mean hand and pelvis velocity, reaction time, punch frequency, and fatigue rate. Results The PAP protocol significantly increased maximum hand velocity (Δ = 0.098 m/s, p = 0.045), maximum pelvis velocity (Δ = 0.010 m/s, p = 0.031), and fatigue rate (Δ = 0.642, p = 0.040), while significantly reducing reaction time (Δ = −0.010 s, p = 0.039). A significant positive correlation was observed between changes in maximum pelvis velocity and maximum hand velocity (r = 0.537, p = 0.018). No significant differences were found in mean velocity or punch frequency (p > 0.05). Conclusion Compared with the traditional warm-up, the PAP-based plyometric warm-up enhanced peak pelvis and hand velocity and improved reaction time during the gyaku-zuki punch. Although the protocol increased fatigue rate, its performance-enhancing effects suggest that it may serve as a practical strategy for optimizing explosive performance and designing individualized warm-up programs for short-duration karate competitions.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Acute Effects of Post-Activation Performance Enhancement-Based Warm-Up Protocols on Knee Joint Kinematics and Countermovement Jump Performance in Male Physical Education Students 394 414 FA MMohammadtaghiammad Taghi Amiri-khorasani Department of Sports Biomechanics, Sport Sciences Research Institute, Tehran, Iran. Fariborz Mohammadi pour Department of Sports Biomechanics, Faculty of Physical Education and Sport Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. Ahmad Shokrollahi Department of Sports Biomechanics, Faculty of Physical Education and Sport Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. Ali Amiri khorasani Department of Sports Biomechanics, Faculty of Physical Education and Sport Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. Objective This study investigated the acute effects of resistance-based and combined post-activation performance enhancement (PAPE) warm-up protocols on knee joint kinematics and countermovement jump (CMJ) performance in male physical education students. Methods This quasi-experimental study used a repeated-measures crossover design. Twenty male physical education students (age: 21 ± 2.00 years; height: 176 ± 5 cm; body mass: 70 ± 5 kg; sport experience: 8 ± 2.2 years) were recruited by convenience sampling. Each participant completed three warm-up conditions in separate, non-consecutive sessions: general warm-up, resistance warm-up, and combined warm-up. The order of conditions was counterbalanced. After each protocol and a 2-min recovery period, participants performed the CMJ. Three-dimensional kinematic data were collected using a six-camera Motion Analysis Raptor-H system sampling at 200 Hz. Outcome variables included jump height, peak knee flexion before take-off and during landing, and peak knee angular velocity during eccentric and concentric phases. Data were analyzed using repeated-measures analysis of variance with Bonferroni-adjusted post hoc comparisons. Results Both resistance and combined warm-up protocols significantly increased jump height, knee flexion, and knee angular velocity compared with the general warm-up condition (p = 0.001). Although the combined protocol produced higher numerical values for several outcomes, no statistically significant differences were observed between the two PAPE-based protocols (p > 0.05). Conclusion PAPE-based warm-up protocols acutely improved CMJ performance and selected knee joint kinematic characteristics. These protocols may be useful as part of pre-activity preparation for explosive tasks when implemented with appropriate load selection and recovery time.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Comparative Analysis of Dual-Task Effects on EMG Activity During Walking in Individuals with Hemiplegic Cerebral Palsy and Healthy Controls 416 436 EN Mobarake Elhami Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Shirin Yazdani Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Mahta Eskandar Nezhad Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Objective The present study aimed to investigate the electromyographic (EMG) activity of lower limb and trunk muscles in individuals with cerebral palsy (CP) and healthy controls during normal and dual-task walking. Methods Twelve CP patients and twelve age-matched healthy volunteers participated in this study. Surface EMG signals from the erector spinae (ES), biceps femoris (BF), and rectus femoris (RF) muscles were recorded during normal walking and motor, cognitive, and visual dual-tasks using a bipolar EMG USB2+ system. Acquired signals were processed using OT Biolab software. Statistical analysis was performed using repeated measures ANOVA in SPSS 22, with significance set at p<0.05. Results Significant differences were observed in normalized EMG of L3, BF, and RF muscles between CP and healthy groups (p<0.001). Motor and visual dual tasks differentially affected muscle activation intensity in both groups (p=0.020). While dual tasks produced symmetrical muscle activation increases in healthy participants, CP patients demonstrated significantly greater left-side activation (p=0.010). Conclusion CP patients exhibited significantly higher EMG activity in L3, BF, and RF muscles across all conditions except normal walking and motor dual-task (where right BF showed no difference). Notably, motor and visual dual-tasks elicited greater muscle activity than cognitive tasks in CP patients, suggesting preferential reliance on visual over proprioceptive feedback due to sensory integration deficits. So, these information, can serve as a useful guide for assessing and designing appropriate exercise and rehabilitation programs for individuals with CP.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Development of EMG-Guided Exercise Protocol (SCAP-SYNC) for Targeting Scapular Dyskinesia in Swimmers 438 459 EN Pradnya Bodake Department of Orthopaedic Physiotherapy, KAHER Institute of Physiotherapy, Nehru Nagar, Belagavi, Karnataka, India. Aarti Welling Department of Orthopaedic Physiotherapy, KAHER Institute of Physiotherapy, Nehru Nagar, Belagavi, Karnataka, India. Peeyoousha Gurudut Department of Orthopaedic Physiotherapy, KAHER Institute of Physiotherapy, Nehru Nagar, Belagavi, Karnataka, India. Vijay Kage Department of Orthopedic Physiotherapy, KLE Institute of Physiotherapy, Belagavi, Karnataka, India. Objective PScapular dyskinesia, characterized by altered scapular motion during shoulder activity, is commonly observed in swimmers and is associated with shoulder pain, reduced performance, and an increased risk of injury. Traditional rehabilitation primarily focuses on strengthening and mobility exercises but lacks real-time monitoring of muscle recruitment. Surface electromyography (EMG) enables direct assessment of muscle activation, allowing athletes to optimize scapular control during training and rehabilitation. To develop an EMG-guided exercise protocol to enhance scapular stabilizer muscle activation in swimmers with scapular dyskinesia. Methods This protocol development study recruited 18 male professional swimmers aged 19–23 years who were diagnosed with unilateral scapular dyskinesia using the Lateral Scapular Slide Test (LSST). Participants performed 15 commonly used scapular stabilization exercises. Surface EMG was used to record bilateral muscle activation of the trapezius (upper, middle, and lower fibers), serratus anterior, infraspinatus, rhomboids, and latissimus dorsi. Peak muscle activation values were compared between the affected and unaffected sides to identify the most effective exercises. Results Five exercises—push-up plus, elbow-knee push-up, lawnmower, Blackburn, and V-W dumbbell drill—elicited significantly greater activation of the scapular stabilizing muscles. These exercises were subsequently integrated into an evidence-based training protocol termed SCAP-SYNC. Conclusion The SCAP-SYNC protocol provides a concise and targeted set of exercises designed to enhance activation of key scapular stabilizers. This protocol may be incorporated into rehabilitation and conditioning programs for swimmers with scapular dyskinesia.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Anaerobic Power Cycling Training and Lower-Extremity Performance in Elite Female Handball Players: A Predictive Model Based on Morphological Indices 460 482 EN Jannatul Ferdaus Rickta Department of Physical Education & Sports Science, Jashore University of Science and Technology, Bangladesh. Fatima Tus Johora Mukta Department of Physical Education & Sports Science, Jashore University of Science and Technology, Bangladesh. Shaik Nazmus Shakib Shaim Department of Physical Education & Sports Science, Jashore University of Science and Technology, Bangladesh. Musfiqur Rahaman Department of Physical Education & Sports Science, Jashore University of Science and Technology, Bangladesh. Yeasir Arafat Physical Education Office; Chittagong University of Engineering & Technology, Bangladesh. Objective Handball requires high levels of anaerobic power, explosive strength, and repeated sprint ability. This study aimed to evaluate the effects of power cycling training on anaerobic capacity and explosive performance in elite female handball players. Methods Forty-three elite female handball players who had participated in the Bangladesh National Female Handball League and had at least five years of continuous handball experience were recruited. Participants were allocated to either a control group (n = 21) or a training group (n = 22). All data were recorded in Microsoft Excel and analyzed using IBM SPSS Statistics version 25.0. Results Between-group comparisons revealed no statistically significant differences in most power cycling variables at baseline (all p > 0.05), confirming group homogeneity. However, significant within-group improvements in mean power and peak power relative to body weight were observed in the training group following the intervention (p < 0.05). Strong positive correlations were identified between peak power performance and lower-extremity skeletal muscle mass as well as thigh circumference (r = 0.91, p < 0.001). Multiple linear regression models explained 86.6% of the variance in peak power and 82.8% of the variance in mean power, indicating that lower-limb morphological indices are reliable predictors of anaerobic cycling performance. Conclusion The training group demonstrated improvements in key Wingate performance variables despite the absence of significant between-group differences. Lower-extremity skeletal muscle mass and thigh circumference were strong predictors of anaerobic cycling performance, and the proposed regression models may offer a practical approach for monitoring anaerobic capacity in female handball players.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Relationships Between Selected Components of Physical Fitness and Skill Performance in Adolescent Female Taekwondo Athletes: A Cross-Sectional Study 484 505 FA Alireza Elhamipour Department of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran. Razieh Yousefian Molla Department of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran. Ali Fatahi Department of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran. Objective Taekwondo is an Olympic combat sport that requires a high level of integration between physical fitness and technical skills. However, evidence regarding the relationships between physical fitness components and skill performance in adolescent female taekwondo athletes remains limited. Therefore, this study aimed to investigate the relationships between selected physical fitness components, including flexibility, explosive power, reaction time, and balance, and skill performance indicators, namely kicking speed, punching power, and combined skill performance, in adolescent female taekwondo athletes. Methods This cross-sectional correlational study employed a quantitative research design. The study included 31 female taekwondo athletes aged 14–18 years with 3–5 years of training experience. Physical fitness components were assessed using the Sit-and-Reach Test (flexibility), Sargent Vertical Jump Test (explosive power), Nelson Ruler Drop Test (reaction time), and Stork Balance Test (balance). Skill performance indicators included kicking speed (FSKT-10s), punching power, and combined skill performance. Data were analyzed using descriptive statistics and Pearson’s correlation coefficient. Results Flexibility was significantly correlated with reaction time (r = −0.38), explosive power (r = 0.36), kicking speed (r = 0.50), and combined skill performance (r = −0.51). Reaction time was also significantly associated with combined skill performance (r = 0.44), whereas kicking speed showed a significant negative correlation with combined skill performance (r = −0.40). In contrast, static balance and punching power were not significantly associated with the assessed skill performance indicators. Conclusion The findings indicate that flexibility and reaction time are significantly associated with skill performance in adolescent female taekwondo athletes. Athletes with greater flexibility and faster reaction times demonstrated superior performance in both kicking speed and combined technical skills. These findings provide practical insights for developing targeted training programs to enhance competitive performance in taekwondo.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Exploring the Effects of Neck Muscle Strengthening on Postural Control: A Systematic Review 506 530 EN Shalini Solanki Physiotherapy Department, GD Goenka University, Gurugram, Haryana, India. Tabish Fahim Physiotherapy Department, GD Goenka University, Gurugram, Haryana, India. Objective The cervical muscles play an important role in postural control, proprioception, and neuromuscular regulation. Weakness or impaired activation of neck and scapular muscles is associated with forward head posture (FHP), neck pain, and altered alignment. Although strengthening and corrective exercises have been suggested to improve cervical function, their comparative effectiveness remains unclear. Methods A systematic review was conducted in accordance with the PRISMA 2020 guidelines. Randomized controlled trials (RCTs) published from January 2015 to July 2025 were identified through searches in PubMed, Cochrane, PEDro, EBSCOhost, and ScienceDirect using the terms “neck muscle,” “fatigue,” and “postural control” and their related combinations. Studies were eligible if they involved individuals with neck dysfunction or postural impairment and evaluated exercise-based strengthening or corrective interventions. The PEDro scale was utilized to evaluate methodological quality. Results Of the 41 identified records, 7 randomized controlled trials (RCTs) were assessed for eligibility; five met the methodological quality threshold (PEDro score ≥ 5) and were included in the final synthesis. The interventions analyzed comprised postural correction exercises, scapular stabilization, kinesiotaping, clinical Pilates, lower trapezius strengthening, and instrument-assisted soft tissue mobilization. These interventions consistently improved craniovertebral angle (CVA), postural alignment, muscle activity, pain levels, and functional outcomes. Multimodal and supervised programs, such as online-supervised exercise, resulted in greater improvements compared with conventional or unsupervised training. Methodological limitations included the absence of blinding and concealed allocation in multiple studies; however, baseline comparability and outcome reporting were typically strong. Conclusion Neck strengthening interventions were associated with improvements in postural control and functional performance across the included trials. Evidence suggests that multimodal, structured, and supervised approaches may provide greater benefits compared with isolated or unsupervised programs. Standardized protocols and long-term follow-up are essential for identifying optimal rehabilitation strategies and assessing sustained benefits.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Comparison of Balance, Power, and Muscular Endurance Among Volleyball Players in Three Attacking Positions 532 544 FA Mehdi Gheytasi Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Shirin Yazdani Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Amir Ghiyami Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tabriz, Tabriz, Iran. Objective The present study aimed to compare balance, power, and muscular endurance among volleyball players in three specialized attacking positions: outside hitter, middle blocker, and opposite hitter. Methods Thirty professional volleyball players were recruited through purposive sampling. Balance was assessed using the Y-Balance Test and a digital balance board. Upper-limb power was evaluated using the medicine ball throw test, whereas lower-limb power was assessed using the standing long jump and vertical jump tests. Core muscular endurance was measured using the plank test. The collected data were analyzed using one-way analysis of variance (ANOVA). Results The results showed no significant differences among the three groups of attacking players (outside hitters, middle blockers, and opposite hitters) in balance, power, or muscular endurance (P > 0.05). Conclusion The findings indicate that professional volleyball players occupying attacking positions exhibit a similar biomechanical profile with respect to balance, power, and muscular endurance. These results suggest that playing position does not substantially influence these general physical performance characteristics. The observed homogeneity may reflect the shared physical demands of modern volleyball, similar training regimens, and the consistently high level of physical preparedness required of all attacking players at the professional level. Therefore, coaches may adopt common foundational training programs for attacking players while reserving position-specific training for technical and tactical skills. Future studies involving larger samples and more sensitive biomechanical assessments are recommended to identify potential position-specific differences.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Comparison of the Effects of Exercise Therapy and Orthokine Therapy on Pain Intensity, Joint Stiffness, and Quadriceps Muscle Strength in Middle-Aged Women with Knee Osteoarthritis 546 568 FA Saeed Ilbeigi Department of Sport Sciences, Faculty of Sport Sciences, University of Birjand, Birjand, Iran. Haniyeh Motedayyen Department of Sport Sciences, Faculty of Sport Sciences, University of Birjand, Birjand, Iran. Mohammad Yousefi Department of Sport Sciences, Faculty of Sport Sciences, University of Birjand, Birjand, Iran. Seyyed Naser Hosseini Physical Medicine and Rehabilitation Specialist, Mashhad, Iran. Effat Hoseinzadeh Department of Sport Sciences, Faculty of Sport Sciences, University of Birjand, Birjand, Iran. Objective Orthokine therapy and exercise therapy are two important approaches for the management of knee osteoarthritis. While the effectiveness of exercise therapy in managing osteoarthritis has been well established, orthokine therapy has recently attracted increasing attention. Therefore, the present study aimed to compare the effects of exercise therapy and orthokine therapy on improving symptoms in patients with knee osteoarthritis. Methods Twenty women with knee osteoarthritis were allocated to exercise therapy and orthokine therapy groups. The exercise therapy group performed exercise training for 4 weeks (three sessions per week), whereas the orthokine therapy group received orthokine injections for 4 weeks (twice per week). Joint stiffness, pain intensity, and quadriceps muscle strength were assessed before and after the interventions using the WOMAC questionnaire, the Visual Analog Scale (VAS), and a dynamometer, respectively. Data were analyzed using repeated-measures analysis of variance with SPSS version 23 at a significance level of p ≤ 0.05. Results Both exercise therapy and orthokine therapy significantly reduced pain intensity and improved quadriceps muscle strength compared with baseline. However, neither intervention produced a significant change in joint stiffness. Furthermore, no significant between-group differences were observed for pain intensity, joint stiffness, or quadriceps muscle strength after the intervention. Conclusion Given the comparable effects of the two therapeutic approaches on symptom improvement, the present study supports the use of exercise therapy as an effective option for managing knee osteoarthritis. Further studies with larger sample sizes and longer follow-up periods are needed to confirm and generalize these results.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Pivoting Gait Reveals Side-Specific Deficits in Horizontal Forces in Adolescent Idiopathic Scoliosis with Lumbar Curvatures: A Cross-Sectional Study 570 604 EN Soha Abbasi Department of Sport Biomechanics, Faculty of Sport Sciences, Bu-Ali Sina University, Hamedan, Iran. Nader Farahpour Department of Sport Biomechanics, Faculty of Sport Sciences, Bu-Ali Sina University, Hamedan, Iran. Bizhan Heidari Department of Orthopedics, School of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran. Gabriel Moisan Department of Human Kinetics, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada. Paul Allard Kinesiology Department, Montreal University, Québec, Canada. Objective This study investigated spatiotemporal parameters and ground reaction force (GRF) components during straight and pivoting gait in adolescents with lumbar adolescent idiopathic scoliosis (AIS), with particular emphasis on differences between left and right lumbar curvatures. Methods In this cross-sectional study, 16 healthy individuals served as the control group (CG), while 14 patients with lumbar adolescent idiopathic scoliosis (AIS) formed the main scoliosis group (MSG), which was further divided into left lumbar (LL) and right lumbar (RL) subgroups. Spatiotemporal parameters and GRF components were analyzed during straight and pivoting gait for the leading, pivoting, and trailing feet. Results No significant differences in spatiotemporal parameters were observed during straight gait. However, during pivoting gait, the right lumbar (RL) subgroup exhibited a longer stance time and altered horizontal ground reaction force (GRF) components. In addition, the RL subgroup showed a greater GRFX1 impulse in the left leading foot than both the control group and the left lumbar (LL) subgroup. No comparable changes were observed in the LL subgroup. Conclusion Right lumbar scoliosis was associated with altered horizontal GRF components during pivoting gait, whereas left lumbar scoliosis showed no comparable changes. These findings suggest that lumbar curvature direction influences neuromusculoskeletal behavior during pivoting and should be considered when developing subgroup-specific rehabilitation strategies.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 Comparison of Knee Contact Force Estimation Errors Between Two OpenSim Musculoskeletal Models During Walking and Squatting 606 624 FA Pooria Asgari Department of Sport Injuries and Biomechanics, Faculty of Sports and Health Sciences, University of Tehran, Tehran, Iran. Shahrzad Zandi Department of Sport Injuries and Biomechanics, Faculty of Sports and Health Sciences, University of Tehran, Tehran, Iran. Farhad Tabatabai Ghomsheh Department of Ergonomics, Pediatric Neurorehabilitation Research Center, School of Rehabilitation Sciences, University of Social Welfare and Rehabilitation Sciences (USWR), Tehran, Iran. Hamid Nikmohammad Department of Sport Injuries and Biomechanics, Faculty of Sports and Health Sciences, University of Tehran, Tehran, Iran. Objective Accurate estimation of musculoskeletal forces is essential for understanding joint biomechanics, improving rehabilitation strategies, and optimizing implant design. Joint reaction forces can be estimated using biomechanical measurements combined with musculoskeletal modeling approaches. This study aimed to compare the accuracy of knee joint contact force estimation between the Gait2392 and Rajagopal musculoskeletal models implemented in OpenSim. Methods Data from six participants (five males and one female; age: 68 ± 5 years; body mass: 88 ± 12 kg; height: 173 ± 4 cm) were analyzed. Biomechanical data collected during walking and squatting tasks were used in this study. After scaling both musculoskeletal models, joint reaction force analyses were performed in OpenSim. Relative errors between predicted knee contact forces and in vivo implant-measured forces were calculated. Statistical Parametric Mapping (SPM) paired t-tests were used to compare modeling errors between the two models at a significance level of 0.05. Results SPM analysis revealed significantly greater estimation errors in the Rajagopal model during the stance phase of walking and across a substantial portion of the squat cycle, particularly in the vertical force component. The RMSE values for the Gait2392 model were 0.835 during walking and 1.536 during squatting, whereas the Rajagopal model demonstrated RMSE values of 1.486 and 3.371, respectively. The coefficient of determination (R²) values for the Gait2392 model were 0.665 during walking and 0.767 during squatting, while the Rajagopal model showed R² values of 0.639 and 0.750, respectively. Conclusion The findings indicate that the Gait2392 model provides more accurate estimations of knee joint contact forces during walking and squatting tasks compared with the Rajagopal model. Therefore, the Gait2392 model may be more suitable for estimating knee joint contact forces in similar low-velocity functional activities.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 The Effect of Thermoplastic Insoles on Center of Pressure Parameters in Individuals with Flatfoot Deformity 626 640 EN Mohammad Yousefi Faculty of Physical Education and Sport Sciences, Department of Sport Sciences, University of Birjand, Birjand, Iran. Rasul Borhani Faculty of Physical Education and Sport Sciences, Department of Sport Sciences, University of Birjand, Birjand, Iran. Masumeh Aleghabi Faculty of Physical Education and Sport Sciences, Department of Sport Sciences, University of Birjand, Birjand, Iran. Sadegh Mohammadnia Ahmadi Department of Neurology, Faculty of Medicine, Birjand University of Medical Sciences, Birjand, Iran. Objective Flatfoot deformity is one of the most common musculoskeletal disorders that can impair postural stability and balance by altering center of pressure (COP) characteristics. Given the importance of non-invasive approaches, the present study aimed to investigate the effect of thermoplastic insoles on COP parameters in individuals with flatfoot deformity. Methods In this quasi-experimental study, 14 eligible participants were randomly assigned to either the intervention group (thermoplastic insole, n=7) or the control group (n=7). Static and dynamic COP data were recorded using a foot-scan system. Following a 45-day intervention period, data collection was repeated. Statistical analyses were performed using paired t-tests and univariate analysis of covariance (ANCOVA) at a significance level of 0.05. Results The findings demonstrated that the use of thermoplastic insoles significantly improved COP parameters in both the mediolateral (ML) and anteroposterior (AP) directions and significantly reduced the Confidence Ellipse Area (CEA) in the intervention group (P<0.05). In contrast, no significant changes were observed in the control group (P>0.05). Conclusion Due to their elastic properties and effective mechanical support, thermoplastic insoles may represent an effective biomechanical intervention for enhancing postural stability and reducing center of pressure (COP) oscillations in individuals with flatfoot deformity.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 12 3 2026 11 1 The Effect of American Academy of Sports Medicine Exercises on Ground Reaction Forces During Walking in Individuals with Hamstring Tightness and Low Back Pain 642 660 FA Mohsen Barghamadi Department of Sports Biomechanics, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran. Makwan Jabbar Ali Department of Sports Biomechanics, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran. Abbas Memarbashi Department of Sports Biomechanics, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran. Reza Noktehsanj Department of Orthopaedic Surgery, Ardebil University of Medical Sciences, Ardebil, Iran. Objective Walking is a fundamental daily activity that depends on coordinated neuromuscular and musculoskeletal function. Hamstring tightness and low back pain may alter gait biomechanics and ground reaction force patterns. This study aimed to investigate the effects of a NASM-based corrective exercise program on ground reaction forces during walking in individuals with hamstring tightness and low back pain. Methods This quasi-experimental study included 30 men aged 20–30 years assigned to experimental (n=15; hamstring tightness and low back pain) and control (n=15; healthy) groups. The experimental group performed an 8-week NASM corrective exercise program, while the control group maintained usual activities. Ground reaction forces were recorded during walking at 2.3 m/s using a Bertec force plate. Data were analyzed using two-way repeated-measures ANOVA in SPSS version 26 at a significance level of 0.05. Results Significant time effects were observed for peak mediolateral ground reaction forces at heel strike (p = 0.024; d = 0.201) and push-off (p = 0.001; d = 0.633). A significant time × group interaction was found for peak anterior–posterior ground reaction force at heel strike (p = 0.001; d = 0.399). Additionally, a significant time × group interaction was observed for peak vertical ground reaction force during push-off (p = 0.010; d = 0.254). The time × group interaction was also significant for the time to peak anterior–posterior ground reaction force at heel strike (p = 0.006; d = 0.276). Conclusion The findings suggest that a NASM-based corrective exercise program may influence specific ground reaction force characteristics during walking in individuals with hamstring tightness and low back pain. These changes may reflect improvements in neuromuscular control and gait mechanics; however, further studies with larger samples are required to confirm these effects.