Search Results (703)

Spontaneous movement analysis provides valuable information about the maturation of the central nervous system and the emergence of motor control strategies in very young babies. Nonlinear measures capture dynamic aspects of movement that cannot be represented by linear methods. However, their implementation in clinical practice faces challenges, including the lack of standardized protocols and accessible tools for routine use. This scoping review aimed to map and characterize the nonlinear measures used to analyze spontaneous infant movement, including assessment context, instruments, data collection protocols, and main variables. The review followed JBI methodology and PRISMA-ScR guidelines. Searches were conducted in PubMed^®, Web of Science™, IEEE Xplore^®, ScienceDirect^®, and Google Scholar for studies published from 1 January 2005 to 31 December 2025. Of 1166 records identified, 18 met the inclusion criteria. The nonlinear measures were grouped into five main methodological families: entropy-based measures (n = 10), state-space and dynamical systems measures (n = 4), recurrence-based analysis (n = 3), symbolic and discrete-state approaches (n = 3), and variance and frequency-based nonlinear descriptors (n = 1). Studies were conducted in laboratory settings (n = 6) and in hospital and/or home environments (n = 10). Two studies did not clearly specify the assessment context. Kinematic assessment was mainly performed using video-based systems (n = 7), accelerometers (n = 4), and wearable sensors (n = 2), with most studies focusing on the upper and lower limbs. Several investigations extended beyond single-joint analyses to examine inter-limb relationships and whole-body configurations, capturing spatial coordination patterns across multiple body segments. Kinetic assessment was conducted using pressure mats (n = 4) and force platforms (n = 1), with the center of pressure displacement as the primary outcome. Future research should prioritise methodological harmonisation and theoretical clarity. Consensus is needed regarding minimal data requirements, parameter selection, and reporting standards for commonly used nonlinear measures. Studies should also move beyond single-metric approaches and adopt multivariate frameworks that integrate complementary nonlinear metrics. The absence of standardised acquisition and analytical protocols currently limits cross-study comparability and hinders the clinical translation of nonlinear movement metrics as objective tools for early neurodevelopmental assessment. Full article

With the increasing number of stroke patients, there is a growing demand for lower-limb rehabilitation exoskeletons. While current mechanisms are preferred for their light weight and dexterous design in limited environments, the alignment of the structures and motion are still not matched perfectly to human movements. This study develops a novel structure and configuration optimization method for knee part rehabilitation with special passive self-alignment modules. The driving segment is mechanically coupled to the patients’ lower limb. All components are designed with high rigidity and fully constrained to ensure smooth and continuous motion. Then, the kinematics are systematically derived to establish the foundation for the control system. Next, the application of the particle swarm optimization algorithm determines the optimal parameters for each revolute joint during the bending motion, and reduces the non-ideal S-shaped motion deformation curve caused by the offset of the joint rotation center and the load at the end effector successfully. The final results demonstrate that the optimized SRE achieves 97.5% motion accuracy under large-angle knee movement. This work presents simulation-only validation, and clinical testing remains future work. The proposed mechanism provides a promising solution for post-stroke rehabilitation, and is also applicable to geriatric lower-limb weakness and orthopedic postoperative recovery. Full article

Post-error slowing (PES) is commonly considered a behavioral marker of post-error adaptation. However, adaptive processes may also emerge through subtle modifications of motor preparation, particularly in combat sports such as taekwondo (TKD), where maintaining rapid motor execution is essential. This study examined post-error neuromuscular adjustments during a TKD-specific kicking task by comparing standard Go and post-error Go trials for changes in muscle onset latency, peak electromyographic amplitude, and co-contraction indices. Twenty-eight TKD athletes (14 novice and 14 advanced) performed a sport-specific Go/No-Go task while wearable wireless surface electromyography sensors recorded lower-limb neuromuscular activity from eight lower-limb muscles. Muscle onset latency, peak electromyographic amplitude, co-contraction indices, and reaction time were analyzed using linear mixed-effects models. Post-error Go trials showed significant alterations in muscle onset latency in posterior lower-limb muscles involved in propulsion and movement preparation (semitendinosus, biceps femoris, lateral gastrocnemius, and soleus), with muscle activation occurring closer to the foot take-off. No significant differences were observed in reaction time, peak electromyographic amplitude, or co-contraction indices, and expertise and age did not modulate these effects. These findings suggest that error-related motor adjustments may be expressed through changes in muscle activation timing rather than overt behavioral slowing. Full article

This study presents the design and development of a wearable lower-limb exoskeleton system aimed at supporting motion assistance in monoplegia-related conditions. The proposed approach integrates a simplified sensing configuration with a data-driven neuro-fuzzy control framework based on an Adaptive Neuro-Fuzzy Inference System (ANFIS). Motion data are acquired from the healthy limb using bend flex sensors and are used to generate control signals for the actuation of the impaired limb through an Arduino-based embedded platform. The mechanical structure is developed using a lightweight 3D-printed design combined with high-torque DC motors and gear transmission mechanisms. Experimental evaluation conducted under controlled conditions demonstrates that the system is capable of capturing and reproducing fundamental motion patterns, with the ANFIS model providing a consistent mapping between sensor inputs and actuator responses. The obtained results indicate a satisfactory level of performance for motion pattern reproduction, particularly in terms of temporal behavior and transition between movement states. The presented system emphasizes low-cost implementation, computational efficiency, and practical implementation, making it suitable as a proof-of-concept framework for wearable assistive technologies. While the results demonstrate the feasibility of the proposed approach for motion reproduction, further studies involving extended testing and user-specific adaptation are required to assess its potential applicability in real-world scenarios. Full article

Objective: Volleyball athletes require well-developed balance control during spiking, blocking, rapid movement, and landing. Joint range of motion (ROM) may also influence limb extension, support adjustment, and center-of-mass control. Previous studies have usually examined balance ability and joint ROM as separate factors related to volleyball performance. However, the associations between dynamic balance, static balance, and multi-joint ROM in the upper and lower limbs remain insufficiently understood. This study therefore aimed to examine the relationship between balance performance and upper- and lower-limb joint ROM in female college volleyball athletes. Methods: Thirty-five female college volleyball athletes were included. Dynamic balance of the upper and lower limbs was assessed using the Y-Balance Test, and static balance was evaluated under eyes-open and eyes-closed conditions using a static balance platform. Upper- and lower-limb ROM was measured using an electronic goniometer and the knee-to-wall test. Paired-sample t-tests were used to compare bilateral differences and differences between visual conditions. Pearson correlation analysis was performed to examine associations between joint ROM and balance performance, and false discovery rate (FDR) correction was applied to account for multiple comparisons. Results: (1) No significant bilateral difference was observed in upper-limb YBT-UQ performance (p > 0.05); for lower-limb YBT-LQ performance, a significant difference was found only in the anterior direction, with the right side showing higher values than the left side (p < 0.01). (2) Static balance parameters under the eyes-closed condition were significantly poorer than those under the eyes-open condition (p < 0.01); under the same visual condition, only the total sway path length of the right foot was significantly shorter than that of the left foot (p < 0.05). (3) The ranges of motion of right shoulder flexion, shoulder horizontal adduction, shoulder external rotation, elbow flexion, and knee-to-wall distance were significantly greater than that of the left side (all p < 0.05), and right hip internal rotation ROM was also significantly greater than that of the left side (p < 0.01). (4) Dynamic balance was correlated with selected joint ROM measures. Specifically, the anterior reach direction of the right YBT-LQ was positively correlated with hip flexion ROM (r = 0.593, p < 0.01) and knee-to-wall distance (r = 0.653, p < 0.01), and these correlations remained statistically significant after FDR correction. (5) Static balance parameters were correlated with selected lower-limb joint ROM measures in the original correlation analysis; however, these correlations did not remain significant after FDR correction. Conclusions: Female college volleyball athletes demonstrated a certain degree of bilateral asymmetry in dynamic balance and a pronounced dependence on visual input during static balance tasks. After FDR correction, the associations between the anterior reach direction of the right YBT-LQ and both hip flexion ROM and knee-to-wall distance remained stable, suggesting that these ROM measures may be related to anterior dynamic balance performance. These findings may provide a reference for postural control assessment and the development of sport-specific training programs for female volleyball athletes. Full article

Assessment of upper-limb kinematics is essential in clinical practice for diagnosis, rehabilitation monitoring, and treatment personalization. Markerless Motion Capture (MMC) systems, such as the Microsoft Azure Kinect (AK), offer a low-cost and time-efficient alternative to marker-based systems. However, while AK accuracy has been extensively studied for lower-limb movements, its performance for upper-limb analysis—especially under clinically relevant, suboptimal conditions—remains underexplored. This study aims to validate AK for upper-limb motion tracking against a gold-standard optoelectronic system under optimal and suboptimal conditions. Sixteen healthy adults performed ten upper body motor tasks in three scenarios: optimal setup, seated posture with table occlusion, and increased camera distance. Joint angles were compared using normalized Root Mean Squared Error (nRMSE) and Pearson’s correlation coefficient. Performance Indicators (PIs) including Range of Motion (ROM), smoothness, and Time to Peak Velocity (TTPV) were also evaluated. AK accurately captured movements performed within the camera plane, with median nRMSE below 20% in optimal conditions and no significant degradation in suboptimal setups. In contrast, movements occurring on planes perpendicular to the camera were poorly captured. ROM estimation was acceptable and highly reproducible, while TTPV showed moderate-to-poor reliability and smoothness deviated substantially from the reference system. These findings suggest that careful attention to Kinect positioning is essential to ensure effective acquisitions, even in suboptimal scenarios. Future research should evaluate AK validity in clinical populations and explore the effects of system interference in multi-device setups. Full article

Double-under jump rope performance requires rapid force production and precise coordination under extreme temporal constraints; however, the biomechanical determinants of elite high-speed performance remain unclear. This ceiling-performance biomechanical study examined speed-dependent motor control in world champions (n = 3, 19.7 years) and junior national champions (n = 5, 14.0 years) during double-under performance at 120 double-unders/min, 140 double-unders/min, and individualized ceiling tempo. Three-dimensional motion capture (300 Hz) synchronized with force plates (1500 Hz) quantified kinetic and kinematic adaptations across tempo conditions. Compared with junior national champions, world champions demonstrated shorter contact times, greater rates of force development, reduced center-of-gravity height and oscillation, more compact posture control with widened upper-limb positioning, smaller rope–foot clearance heights, and an increasingly ankle-dominant coordinative pattern between wrist–hand control and lower-limb movement under ceiling-tempo conditions. Collectively, these findings indicate distinct expertise-dependent differences in force-production, postural-control, and rope-coordination characteristics under ceiling-tempo conditions. In contrast, junior national champions demonstrated less pronounced temporal compression, maintained a comparatively extended posture, and appeared to approach a performance plateau beyond 140 double-unders/min. The findings provide biomechanical benchmarks for understanding ceiling-tempo performance and may inform training, movement retraining, and injury-prevention strategies in high-speed cyclic movement tasks. Full article

Female rugby league performance is influenced by multiple interacting sensory and physiological systems; however, the extent to which these factors vary across playing levels and positional groups remains unclear. This study explored differences in visual, vestibular, somatosensory, and autonomic performance according to playing level and position in female rugby league athletes. Elite and sub-elite athletes completed lower-limb proprioception testing using the Active Movement Extent Discrimination Assessment protocol alongside visual-vestibular and autonomic assessments obtained via a virtual reality eye-tracking system. Bayesian hierarchical models examined the effects of playing level, positional group (adjustables, backs, forwards), and their interaction. Few consistent differences were observed between elite and sub-elite athletes across the measures assessed. Posterior estimates suggest selected level-by-position effects for ankle proprioceptive acuity (PD = 0.94), vestibulo-oculomotor time on target (PD = 0.95), and autonomic dilation velocity (PD = 0.98); however, these findings were not consistent across positional groups or outcome measures, and within-group variability was evident. Overall, sensory and autonomic performance did not consistently differentiate elite and sub-elite athletes, suggesting limited utility as cross-sectional markers of playing level but potential value as longitudinal monitoring tools alongside workload, recovery, and performance data. Full article

This study compared the effects of variable-resistance compound training versus constant-resistance compound training on lower-limb explosive power in judo athletes, aiming to identify an effective and safe training method. Methods: Sixteen judo athletes were randomized into VRT (n = 8) or RT (n = 8) groups for a 6-week, twice-weekly intervention. Outcomes included rate of force development (RFD), counter movement jump (CMJ), squat jump (SJ), eccentric utilization ratio (EUR), reactive strength index (RSI), squat 1RM, muscle architecture, and Special Judo Fitness Test (SJFT). After 6 weeks of training intervention, the time × group interaction effects were significant between the variable-resistance compound training group and the constant-resistance compound training group in the following parameters: CMJ (p < 0.01, η² = 0.605), SJ (p < 0.01, η² = 0.391), EUR (p < 0.01, η² = 0.308), RSI (p < 0.01, η² = 0.306), RFD (p < 0.01, η² = 0.401), squat 1RM (p < 0.01, η² = 0.328), SJFT index (p < 0.01, η² = 0.537), femoral rectus feather angle (p < 0.05, η² = 0.380), femoral rectus thickness (p < 0.05, η² = 0.288), femoral rectus cross-sectional area (p < 0.01, η² = 0.868), gastrocnemius feather angle (p < 0.05, η² = 0.274), and gastrocnemius thickness (p < 0.05, η² = 0.390). No significant group effects were observed for any of the parameters (p > 0.05). Conclusion: Both variable-resistance training (VRT) and constant-resistance training (CRT) are effective in enhancing lower-body power in judo athletes; both training methods can be regarded as effective options for developing lower-body power in judo athletes, although VRT may offer a slight advantage in specific performance domains. Full article

Combat sports are characterized by sport-specific asymmetrical movement patterns that may influence neuromuscular control, functional stability, and injury risk. Although lower-limb asymmetry has been widely investigated in taekwon-do experienced ITF taekwon-do practitioners, upper-limb functional symmetry remains insufficiently explored. Sixteen experienced male ITF taekwon-do practitioners underwent assessment of hand grip strength and upper-limb dynamic stability using the Upper Quarter Y-Balance Test (UQYBT). Reach distances in anterior (AP), posteromedial (PM), and posterolateral (PL) directions were analyzed together with composite symmetry indices. Inter-limb differences were evaluated using paired Student’s t-tests, and associations between strength and dynamic stability variables were examined using Pearson’s correlations. Significant inter-limb asymmetry was observed only in the posteromedial (PM) UQYBT direction, with higher values for the left upper limb (p < 0.001; dz = 1.34). No significant inter-limb differences were observed for hand grip strength, anterior reach distance, posterolateral reach distance, or composite index values. Correlation analyses demonstrated weak-to-moderate and statistically non-significant relationships between hand grip strength and dynamic stability variables. Experienced taekwon-do athletes demonstrate movement-specific upper-limb asymmetry while maintaining relatively symmetrical overall dynamic stability and grip strength. The findings further suggest that upper-limb dynamic stability may depend more strongly on neuromuscular coordination and sport-specific motor control than on maximal grip strength alone. These findings suggest that asymmetry in taekwon-do may reflect a potential sport-specific adaptation rather than generalized neuromuscular dysfunction. Full article

Marker-based motion capture systems are considered the gold standard for biomechanical analysis of movements associated with anterior cruciate ligament (ACL) injury risk; however, their cost and technical requirements limit their use for large-scale athlete screening. Markerless motion capture has emerged as a potential alternative, using pose estimation algorithms or depth cameras to quantify movement without reflective markers. This systematic review evaluated the accuracy and validity of markerless motion capture systems for measuring lower-limb kinematics during jump-landing tasks commonly used in ACL injury screening. MEDLINE, Embase, and Web of Science were searched from 1990 to March 2025 for studies comparing markerless and marker-based systems in healthy participants. Extracted outcomes included Bland-Altman plots, root mean square error, mean absolute error, Pearson’s correlation coefficient, coefficient of multiple correlation, and intraclass correlation coefficient. Across studies, markerless systems demonstrated moderate to high validity for several lower-limb kinematic measures, particularly in the sagittal plane, although validity varied across joints, movement phases, and task complexity. These findings suggest markerless motion capture shows potential for biomechanical assessment in ACL injury screening, but further validation is required before widespread implementation. Full article

Objective: This study aimed to compare the neuromuscular control characteristics of international- and national-level squash players during forehand strokes using a multichannel surface electromyography (sEMG)-based sensing framework. By integrating wearable biosignal acquisition with muscle synergy and intermuscular coherence analyses, this study sought to identify sensor-derived markers of performance-related neuromuscular control and to provide evidence for sensor-informed squash training and athlete monitoring. Methods: Participants performed standardized forehand strokes, during which multichannel sEMG signals were synchronously collected from major upper-limb, lower-limb, and trunk muscles. The recorded sensor signals were preprocessed and analyzed using non-negative matrix factorization to extract muscle synergies, including the number of synergies, muscle weightings, and synergy activation durations. In addition, time–frequency intermuscular coherence analysis was performed on the sEMG sensor data to quantify coherence differences in the α, β, and γ frequency bands between upper-limb–trunk and lower-limb–trunk muscle pairs. Results: No significant difference was found between the two groups in the number of muscle synergies, with both groups clustering into four synergy modules. However, the sEMG sensor-based analysis revealed clear between-group differences in synergy structure and coordination patterns. International-level players showed higher muscle weightings in major proximal muscles, including the deltoid, pectoralis major, erector spinae, and gluteus maximus, and lower weightings in relatively smaller or more distal muscles such as the biceps brachii and lateral gastrocnemius. In terms of synergy timing, international-level players exhibited significantly shorter activation durations in SYN1 and SYN2, but a significantly longer activation duration in SYN3, than national-level players. For intermuscular coherence, international-level players showed significantly lower coherence in the α, β, and γ bands for multiple upper-limb–trunk and lower-limb–trunk muscle pairs. Conclusions: A multichannel sEMG sensing approach was effective in detecting performance-level differences in neuromuscular control during the squash forehand stroke. International-level players exhibited more efficient and refined neuromuscular coordination, characterized by optimized proximal muscle recruitment, more task-specific synergy timing, and reduced intermuscular coherence across selected muscle pairs. These findings highlight the value of wearable EMG sensors and sensor-based neuromuscular feature extraction for quantitative athlete assessment, movement monitoring, and the development of sensor-guided training strategies in squash. Full article

Breast cancer is the most prevalent malignancy among women. The disease and its treatments often lead to physical and psychosocial impairments, compromising quality of life. While exercise and music-based interventions have individually demonstrated benefits on these symptoms, the advantages of their combination remain unexplored. This study evaluates whether a concurrent exercise program, including aerobic and strength training performed while listening to music based on individual preferences, is more effective than the same exercise program without music in improving self-esteem, body image, cancer-related fatigue, physical function (upper and lower limb strength and cardiorespiratory endurance), quality of life, sleep quality, and intolerance of uncertainty in female breast cancer survivors. A single-blind, two-arm, parallel-group, randomized controlled trial will be conducted including 42 women who completed primary treatment for stage 0–III breast cancer at least six months before enrollment. Participants will be randomly assigned to a music-listening concurrent exercise training group (MLTG), or a no music exercise training group (NMLTG), both performing the same 8-week exercise program. The primary outcome will be self-esteem (Rosenberg Self-Esteem Scale). Secondary outcomes include body image, fatigue, upper and lower limb strength, cardiovascular endurance, quality of life, sleep quality, and intolerance of uncertainty. Measurements will be collected using validated and reliable questionnaires and standardized functional tests at baseline, post-intervention, and at 6 months. Data will be analyzed under the intention-to-treat principle. Music listening, particularly when based on individual preferences and synchronized with movement, may enhance mood and exercise performance while modulating reward-related neural pathways. This trial will provide new evidence on a feasible and low-cost strategy to enhance supportive care and physical and psychosocial outcomes in breast cancer survivors. ClinicalTrials.gov (NCT07045961). Ethics Committee code: 2025-0855. Full article

Continuous monitoring of lower-limb kinematics in natural environments is essential for gait analysis and rehabilitation but remains challenging due to the limitations of optical systems and the inaccuracy of sparse inertial sensor methods. To address this, we propose a high-precision, minimalist wearable system utilizing only three inertial measurement units placed on the pelvis and shanks. In the data preprocessing stage, engineering modifications are made based on the traditional gradient descent algorithm to implement adaptive channel adjustment on the acceleration and magnetic data of a single IMU, aiming to alleviate the impact of motion acceleration and external magnetic interference on the temporal feature manifold. Subsequently, a pure Transformer neural network is utilized to capture long-range temporal dependencies, reconstructing full lower-limb kinematics without relying on rigid biomechanical assumptions. The model was optimized and deployed on an STM32N647 microcontroller to achieve real-time edge inference with a low latency of approximately 17 ms. Experimental results demonstrate that the proposed method achieves a mean absolute error of 2.41° for level walking, significantly outperforming traditional constrained Kalman filter approaches. Furthermore, it maintains high tracking robustness during complex nonlinear movements such as squatting and lunging. In conclusion, this edge-computing-enabled framework provides an accurate, comfortable, and real-time solution for unconstrained human motion capture in daily scenarios. Full article

This exploratory study compares the Froude efficiency (η_F), intra-cyclic speed fluctuation (ICSF) and other performance determinants between two freestyle swimming techniques: double-arm backstroke and front crawl, and then demonstrates how Para swimmers with hypertonia differ from non-disabled swimmers when performing double-arm backstroke. Three-dimensional motion analysis was undertaken on three Para swimmers with hypertonia (sport classes 3–4) and eight non-disabled swimmers performing a simulated double-arm backstroke with lower limbs immobile. The non-disabled group also completed front crawl trials. Swimming speed, stroke frequency, stroke length and η_F were significantly greater, and ICSF significantly lower, during front crawl than during double-arm backstroke in non-disabled swimmers. Para swimmers’ double-arm backstroke speed was 45–52% that of the non-disabled group; their stroke length was 58–69% shorter and stroke frequency 26–53% higher. Non-disabled swimmers demonstrated higher peak elbow extension velocity during the push phase than Para swimmers (6.36 ± 1.26 rad∙s⁻¹ vs. 1.50–1.81 rad∙s⁻¹) and their η_F was approximately double the Para swimmers’ (0.33 ± 0.02 vs. 0.14–0.18). Para swimmers displayed poorer body alignment than the non-disabled group; ICSF did not differ between groups. Double-arm backstroke is slower and less efficient than front crawl. Hypertonia may reduce the efficiency of double-arm backstroke by diminishing propulsive movements and worsening body orientation. Full article