Search Results (1,019)

Background/Objectives: The muscle synergy framework suggests that the central nervous system simplifies hand motor control by recruiting coordinated groups of muscles. However, the organization of these synergies across functional grasp types representative of activities of daily living remains incompletely understood. This study aimed to characterize muscle synergies across functional grasps and identify shared coordination patterns relevant for neuromuscular assessment. Methods: Muscle synergies were analysed in 26 healthy participants using a publicly available surface electromyography dataset. Five representative functional grasp types were selected, (cylindrical, lateral pinch, lumbrical, oblique, and tridigital pinch) and synergies were extracted using non-negative matrix factorization. Results: Four to five muscle synergies accounted for more than 90% of EMG variance across all grasp types. Despite grasp-specific differences, a consistent set of shared synergies was identified across conditions, explaining 92.5% of the total variance and being flexibly modulated depending on task demands. Extensor-related components showed a particularly consistent contribution across grasps. Conclusions: Functional hand grasping relies on a compact and reusable set of muscle synergies that are flexibly adapted to task demands. These findings support a modular organization of neuromuscular control and provide normative references that may be useful for the assessment of altered motor control in neuromuscular disorders, with potential applications in neurorehabilitation and assistive technologies. Full article

Background/Objectives: Muscular dystrophies (MDs) are progressive neuromuscular disorders in which rehabilitation is central to management, yet conventional physical therapy in children is constrained by motivation, accessibility, and the need to adapt across disease stages. Virtual reality (VR) offers an interactive, adaptable, and home-deliverable alternative, but prior reviews focused narrowly on upper-limb outcomes in Duchenne muscular dystrophy or on motor-learning paradigms. We aimed to evaluate VR-based rehabilitation in children and adolescents with MD across feasibility/adherence, engagement and psychological outcomes, and clinical motor outcomes, and to propose a stage-based conceptual framework. Methods: PubMed, Embase, and Cochrane CENTRAL were searched on 21 April 2026, following PRISMA 2020 (PROSPERO CRD420261380539). Eligible studies enrolled children or adolescents (mean age ≤ 18 years or separable pediatric data) with any MD who received VR/AR/MR/exergame/serious-game rehabilitation. Risk of bias was assessed with RoB 2.0 and ROBINS-I, and certainty with GRADE. Given substantial heterogeneity, findings were synthesized narratively by disease stage. Results: Eight studies (2017–2024; 221 participants) met the inclusion criteria. No serious VR-related adverse events occurred, and feasibility and tolerability were consistently favorable. Engagement and psychological outcomes showed favorable trends, including sustained motivation and reduced perceived fatigue. Clinical motor outcomes were heterogeneous and stage-dependent. Conclusions: The evidence base is limited and clinically heterogeneous, precluding meta-analysis, with Low GRADE certainty for feasibility, safety, and adherence and Very low for the remaining four domains. Key limitations include small sample sizes, substantial clinical and methodological heterogeneity, and only a single advanced-stage study. The findings provisionally support a stage-dependent role for VR-based rehabilitation in pediatric MD: motor training in the ambulatory stage, upper-limb maintenance and interface-adapted training in the transitional stage, and feasibility-, engagement-, and psychological-support applications in advanced disease. Stage-stratified trials with standardized, domain-specific outcomes and explicit virtual-to-real transfer assessment are warranted. Full article

Background: Cancer cachexia and sarcopenia are highly prevalent complications affecting up to 50% of patients with cancer and are associated with increased treatment toxicity, poorer functional outcomes, and reduced survival. Early identification of muscle deterioration during hospitalization remains challenging. Objective: To evaluate the change in dominant-hand handgrip strength between hospital admission and discharge in hospitalized oncology patients. Methods: This prospective longitudinal study will evaluate hospitalized adults with confirmed malignancy and an expected hospital stay of ≥5 days. Daily handgrip strength and sEMG assessments will be performed as exploratory secondary measures to characterize temporal patterns of muscle function during hospitalization. Baseline and discharge evaluations will additionally include bioelectrical impedance analysis, validated patient-reported outcome measures (SARC-F, EORTC QLQ-C30, PSQI), and serum biomarkers related to inflammatory and nutritional status. Linear mixed models will be used to evaluate longitudinal changes and associations between functional, electrophysiological, and biochemical parameters. Expected results: The study aims to characterize trajectories of muscle function decline during hospitalization, identify candidate biomarker signatures for cachexia detection, and evaluate neuromuscular fatigue patterns using sEMG. Conclusions: This protocol proposes a feasible multimodal framework for monitoring skeletal muscle deterioration during acute oncology hospitalization and may inform future interventional strategies targeting cancer-related cachexia and sarcopenia. Full article

Background/Objectives: The Dynamic Strength Index (DSI) has been proposed as an indicator of the ability to dynamically express maximum available strength; however, its practical significance remains unclear. This study examined the associations of the DSI with dynamic and isometric strength measures, as well as sprint performance, in female professional soccer players. Methods: Eighteen female professional soccer players were assessed during pre-season. The DSI was calculated from peak force obtained in the countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP). Spearman’s correlations were analysed alongside bootstrap confidence intervals, false discovery rate (FDR) adjustment, dependent correlation comparisons, and partial correlations controlling for body mass. Results: The DSI showed moderate unadjusted associations with relative CMJ peak force (ρ = 0.59) and relative CMJ peak yank (ρ = 0.56). However, no associations remained statistically significant after FDR correction. Despite this, the overall pattern of effect sizes and confidence intervals suggested a tendency towards stronger associations with dynamic rather than isometric variables. No meaningful associations were observed with IMTP-derived variables or sprint performance. Conclusions: In this exploratory sample, the DSI showed a tendency towards stronger associations with relative dynamic force variables than with isometric measures. However, given the lack of statistical significance after correction for multiple comparisons, these findings should be interpreted cautiously. The DSI may be better considered as a complementary metric within a broader neuromuscular assessment framework rather than as a standalone indicator. Full article

Background: Pelvic floor dysfunction (PFD) is frequent in neurological disorders, but it is often approached as a secondary urological or gynecological problem rather than a functional rehabilitation target. Neurological disease can disturb cortical, pontine, spinal, sacral, autonomic, somatic, and sensory pathways that regulate bladder storage, voiding, bowel evacuation, sexual function, and pelvic pain modulation. Methods: This narrative review synthesized biomedical evidence identified through PubMed searches from database inception to 2 May 2026. Search concepts included neurogenic lower urinary tract dysfunction, urinary and bowel dysfunction, sexual dysfunction, pelvic pain, pelvic floor rehabilitation, biofeedback, electrical stimulation, neuromodulation, telerehabilitation, robotics, and major neurological disorders. The review was oriented according to the Scale for the Assessment of Narrative Review Articles (SANRA) and was not designed as a systematic review or meta-analysis. Results: Evidence from multiple sclerosis, stroke, Parkinson’s disease, Alzheimer’s disease and related dementias, spinal cord injury, and fibromyalgia or nociplastic pain syndromes supports a phenotype-based framework in which pelvic floor muscle training, bladder and bowel training, biofeedback, neuromuscular electrical stimulation, posterior tibial nerve stimulation, sacral neuromodulation, telerehabilitation, robotics, and multidisciplinary care are considered complementary rather than interchangeable strategies. Conclusions: PFD in neurological disorders may be more appropriately conceptualized as a multidimensional neurorehabilitation target. Effective care depends on disease-informed phenotyping, individualized rehabilitation goals, attention to cognition and adherence, and standardized outcome measurement. Future studies should test phenotype-specific pathways that integrate bladder, bowel, sexual, pain, participation, safety, and caregiver outcomes. Full article

Background/Objectives: This study investigated kinetic performance, leg stiffness and gastrocnemius muscle (GM) activity during shod and barefoot two-legged hopping in female court athletes, while also assessing potential sport specialization-by-footwear interactions. Methods: Forty-two elite female Volleyball, Basketball, and Handball athletes (n = 14 per group) performed two-legged hopping at 130 bpm under both shod and barefoot conditions. Vertical ground reaction force (Fz) (Kistler forceplate sampling at 1000 Hz) was recorded in synchronization with GM vibromyographic intensity (TSD250, Biopac Systems, sampling at 2000 Hz). Kinetic metrics, kleg and GM activation were analyzed via repeated-measures ANOVA (alpha = 0.05, PSS 30.0). For all metrics, results indicated no significant sport-by-footwear interaction (p > 0.05). Results: Footwear significantly altered hopping kinematics; while absolute contact durations remained constant, relative total and effective contact durations were elongated and shortened, respectively. In the shod condition, kleg increased (+6.1%, p < 0.05) alongside a reduction in GM activation (−7.7%, p < 0.05). Additionally, Fz peak increased (+4.3%, p < 0.05) and occurred relatively earlier in the contact phase (−0.7%, p < 0.05). Conclusions: These findings indicate that footwear acts as a mechanical buffer, enabling a stiffer leg spring and reduced neuromuscular demand. The earlier timing of Fz peak suggests a facilitated eccentric-to-concentric transition, most likely allowing athletes to maintain efficient energy return despite the compliance of the footwear interface. Full article

Background: Echo intensity (EI) derived from ultrasound imaging is widely used to assess muscle quality and has been proposed as a potential indicator of neuromuscular performance. Recently, EI band analysis has been suggested as an alternative approach to provide additional information beyond mean EI. However, evidence linking EI bands to functional outcomes remains limited. Methods: Forty-eight male soccer players (26.2 ± 3.6 years) underwent ultrasound assessment of the vastus lateralis (VL) and rectus femoris (RF) muscles. EI was analyzed as mean values and as pixel distribution across five bands (0–50, 51–100, 101–150, 151–200, and 201–255 A.U.), with correction for subcutaneous adipose thickness. Knee extensor peak concentric torque and total work were assessed using isokinetic dynamometry at 60°/s. Generalized linear regression models were used to examine associations between EI variables and mechanical outcomes. Results: No significant differences were observed between limbs for EI mean or EI band distribution in either muscle. The 0–50 A.U. band exhibited the highest pixel percentage for both VL and RF. Mean EI of the RF was negatively associated with peak torque (β = −4.10; 95% CI: −7.35 to −0.86) and total work (β = −3.89; 95% CI: −6.34 to −1.45) of the right knee extensors. No significant associations were found for EI bands or for any EI variables of the VL muscle. In male soccer players, mean EI of the rectus femoris, but not EI band distribution, is associated with knee extensor torque and work output. Conclusions: These findings suggest that mean EI remains a more informative indicator of muscle quality related to strength performance than band-based EI analysis in this athletic population. Full article

Limited evidence exists regarding longitudinal changes in neuromuscular function throughout a competitive season and following time-loss injuries in professional football. The aim of this study was to explore the longitudinal alterations related to time-loss injuries on surface electromyography (SEMG) and vertical jump performance in professional football players. Fourteen U-23 male professional football players were assessed at two time points during the 2019–2020 competitive season. SEMG activity of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, and semitendinosus was evaluated during the bulgarian squat (BS) and single knee straight bridge (SKSB) exercises. Vertical jump performance was assessed using squat jump (SJ) and countermovement jump (CMJ) tests performed on force platforms. Participants were classified as players experiencing time-loss injuries (IPs; n = 6) or players who remained continuously available (NIPs; n = 8) according to the occurrence of a time-loss injury (>8 days). Repeated-measures ANOVA was used to examine the effects of time point, group, limb, and exercise phase. Significant time point × group interactions were observed for CMJ inter-limb asymmetry variables, with IPs demonstrating reduced asymmetry values over time. During the SKSB exercise, biceps femoris activation was significantly lower in IPs (η²p = 0.38) compared with NIPs. No consistent alterations related to time-loss injuries were identified during the BS exercise. No consistent differences related to time-loss injuries were observed in conventional vertical jump performance measures. These observations suggest that SEMG assessment during posterior-chain exercises may provide complementary information regarding neuromuscular function in professional football players experiencing time-loss injuries beyond that obtained from conventional vertical jump assessments. Nevertheless, these observations should be interpreted with caution given the small sample size, the heterogeneous injury profile, and the exploratory nature of the present investigation. Full article

Background: Professional triathlon training is widely recognized as one of the most physiologically demanding forms of training, combining the multicomponent development of physical, biomechanical, and neuromuscular capacities across the three disciplines of swimming, cycling, and running. In this research, the authors measured the impact of two different training periods in elite male athletes on the serum concentrations of GLP-1, GIP, testosterone, and NF-κB and assessed their potential correlations. Methods: We compared a group of 37 triathletes, aged between 25 and 50, during preparatory and competitive periods, with a group of 20 healthy untrained males. The aim of the study was to assess the concentrations of testosterone, GLP-1, GIP, and NF-κB in both groups and in different exercise periods. We determined the markers using the ELISA method. Results: The results demonstrated an increase in GLP-1 concentration between two training groups (preparatory 44.73 ± 5.34 (pmol/L) vs. competitive 45.92 ± 6.13 (pmol/L); p < 0.001). Moreover, higher values of GIP serum concentration were observed in the training groups compared to the control group (33.21 ± 3.54 (ng/mL) vs. 38.83 ± 4.5 (ng/mL); p = 0.038). There were no statistically significant differences (p > 0.05) between the groups in terms of testosterone and NF-κB concentrations. There was also a statistically significant, strong positive correlation between NF-κB and GLP-1, GIP during each training period. In spite of the absence of definite changes in mean values of testosterone concentration between the groups, a minor increase in the median value in the group during the competitive period and a significantly lower median value in the control group were detected, suggesting a trend toward statistical significance. Conclusions: These findings may have clinical significance in athletes, as incretins and NF-κB could serve as biomarkers of metabolic adaptation to exercise and support individual training optimization. Further research is needed to investigate these relationships. Full article

Bilateral deficit (BLD) is traditionally defined as the reduced capacity to produce force during simultaneous bilateral contractions compared with the summed output of unilateral actions. However, in applied sport settings, BLD is frequently estimated from countermovement jump (CMJ) performance, representing a functional rather than a direct mechanical measure of force production. Therefore, the aim of this study was to examine the association between a CMJ-derived functional BLD index and multidirectional performance in soccer players. Forty male university soccer players (age: 23 ± 1 years) performed unilateral and bilateral CMJ. The BLD index was calculated from jump height values obtained during these assessments. Participants subsequently completed the 505 change-of-direction (CoD) test, which was analyzed using two-dimensional video-based motion analysis. Participants were classified according to BLD magnitude into low, moderate, and high BLD groups. Group differences were assessed using Kruskal–Wallis tests with Bonferroni-adjusted post hoc comparisons. Additionally, Spearman correlation analyses were performed using BLD as a continuous variable. Significant between-group differences were observed across all temporal phases of the 505 test (p < 0.001), with players exhibiting lower BLD values demonstrating superior acceleration, deceleration, reacceleration, and overall CoD performance. Significant negative correlations were also observed between BLD and reaction time, acceleration, deceleration, reacceleration, CoD time, and CoD deficit (r_s = −0.42 to −0.69; p < 0.001). No significant associations were found for stride length, acceleration ability, or inter-limb asymmetry. These findings suggest that lower magnitudes of a CMJ-derived functional BLD index are associated with superior multidirectional performance in soccer players. However, given that BLD was estimated from jump performance, the results should be interpreted as associations with a functional neuromuscular performance index rather than as direct evidence of bilateral force production capacity. Full article

Background: Muscle cramps are sudden, painful, and recurrent contractions that may interfere with physical activity and daily life. Although stretching is commonly used to relieve cramps, the effectiveness of neuromuscular electrical stimulation (NMES) has not been fully established. Objective: This study aimed to investigate the effects of NMES on cramp threshold frequency (CTF) and pain intensity in individuals with a history of nocturnal leg cramps without identifiable underlying disorders. Methods: Twenty healthy adults with a history of leg cramps were randomly assigned to either an experimental group (n = 10) or a control group (n = 10). The experimental group received electrical stimulation to both calves using an NMES device, whereas the control group performed lower-extremity static stretching exercises. Both groups participated in an intervention program conducted three times per week for 20 min per session over 4 weeks. CTF was measured using surface electromyography, and muscle cramps were induced using an electrical stimulation device starting at 4 Hz, with the frequency increased by 2 Hz after each stimulation set until cramp onset. Pain intensity was assessed using the Visual Analog Scale (VAS). Within-group and between-group comparisons before and after the intervention were analyzed using paired-samples t-tests and independent-samples t-tests, respectively, with the level of statistical significance set at p < 0.05. Results: Both groups showed significant improvements in CTF and pain intensity after the intervention. However, the NMES group demonstrated significantly greater improvement than the stretching group. The increase in CTF was significantly greater in the experimental group than in the control group (9.20 ± 6.75 vs. 1.80 ± 1.75; t = 3.357, p = 0.007). Likewise, the reduction in VAS score was significantly greater in the experimental group than in the control group (−5.20 ± 0.92 vs. −1.60 ± 0.84; t = 9.128, p < 0.001). Conclusions: NMES may be an effective intervention for increasing cramp threshold frequency and reducing pain in individuals with leg cramps, with greater benefits than lower extremity stretching. Full article

Background: Knee osteoarthritis (KOA) alters the performance of daily activities, such as stair negotiation, by compromising lateral stability and neuromuscular control. This pilot study aimed to evaluate the feasibility of a 10-week Dynamic Neuromuscular Stabilization (DNS) program and to explore its preliminary biomechanical effects during stair ascent and descent in middle-aged women with KOA. Methods: Twenty-six participants were randomly assigned to a DNS group (n = 13) or a control group (n = 13). The DNS group completed a 10-week intervention (twice weekly). Feasibility was assessed via recruitment, retention, and adherence. Primary outcomes were mediolateral (ML) center of pressure (COP) parameters, while secondary outcomes included anteroposterior (AP) COP parameters and lower limb range of motion (ROM). Effect sizes (η²_p) were estimated using 3D motion analysis and force plates. Results: The intervention showed high potential feasibility, with 100% recruitment and retention rates and 98.5% compliance. No adverse events occurred. Large effect sizes were observed for reduced ML COP velocity (ascent: η²_p = 0.79; descent: η²_p = 0.62) and RMS (descent: η²_p =0.16). Secondary outcomes, including AP COP parameters and joint ROM (increased sagittal flexion and decreased coronal instability), also demonstrated large effect sizes. Conclusions: This pilot study suggests that progressive DNS training appears to be feasible and safe for patients with KOA. The preliminary effect sizes observed in COP control and lower kinetic chain mechanics may serve as useful foundational data for designing future adequately powered clinical trials to further examine the efficacy and underlying biomechanical mechanisms of DNS training. Full article

Prolonged sitting is a common occupational exposure among administrative and office workers and is associated with increased postural muscle stiffness, fatigue, and musculoskeletal discomfort. This study aimed to evaluate whether a dedicated physiotherapeutic training programme can reduce biomechanical indicators of muscle overload in sedentary administrative staff. Forty-five female administrative employees were allocated to an intervention group (n = 22) or a control group (n = 23). The intervention group completed a four-week supervised physiotherapeutic programme comprising three 45 min sessions per week, including stretching, strengthening, and sensorimotor exercises targeting postural muscles. Muscle stiffness was assessed using myotonometry, while muscle fatigue was evaluated with surface electromyography based on median frequency slope analysis. The intervention effect was assessed using ANCOVA, with post-intervention values adjusted for corresponding baseline values. The intervention group showed significant reductions in muscle stiffness and fatigue, particularly in the upper trapezius and thoracic erector spinae, with moderate-to-large effect sizes. These findings indicate that targeted physiotherapeutic training can improve neuromuscular function and fatigue resistance in sedentary workers. Incorporating structured physiotherapeutic exercise into workplace health programmes may support musculoskeletal resilience and reduce the biomechanical consequences of prolonged sitting. Full article

Countermovement jump (CMJ) analysis is widely used to assess lower limb neuromuscular function, but commercial force plates often suffer from high cost, closed algorithms, and lack of bilateral independent measurement. This study developed and evaluated a dual channel strain gauge force plate system featuring open architecture and hardware-triggered video synchronization. The system consists of two physically isolated plates, each with four full bridge strain beams, a precision analog front end, and a 2000 Hz acquisition unit. A microcontroller-based hardware trigger synchronizes force data with video capture. Custom host software implements adaptive jump phase recognition and calculates peak force (PF), concentric impulse, jump height, rate of force development (RFD), and asymmetry index (ASI). Validation included static mass measurements in 14 participants, low-load static calibration (5.0–30.0 kg), free-fall impulse validation (7.00 to 31.32 N·s), 240 fps high-speed video cross validation of flight time, ecological-validity comparison with published AMTI-based force-plate data, and 48 h test–retest reliability assessment. Static mass measurement showed a mean absolute percentage error (MAPE) of 1.01% and a coefficient of determination (${\mathrm{R}}^2$) of 0.9992, while low-load testing confirmed excellent linearity (${\mathrm{R}}^2>0.996$) and minimal absolute error (mean absolute error = 0.34 kg) at lighter weights. Dynamic impulse validation yielded ${\mathrm{R}}^2>0.997$ and MAPE < 3%. Flight time agreement with high-speed video was within ±10 ms. Test–retest reliability was excellent for concentric impulse (intraclass correlation coefficient (ICC) = 0.997) and jump height (ICC = 0.987), and good for PF (ICC = 0.962) and rate of force development at 100 ms (RFD_100ms) (ICC = 0.883). The physically isolated dual-plate architecture effectively captured bilateral force differences, although the ASI demonstrated moderate reliability (ICC = 0.748), likely reflecting the inherent biological variability in bilateral coordination. The ecological-validity comparison further indicated that the macroscopic kinetic outputs of the proposed system fell within the expected physiological and biomechanical ranges reported for adult CMJ testing. Overall, these findings support the study hypothesis that the proposed dual-channel force plate system provides a valid, reliable, and cost-effective solution for synchronized bilateral CMJ kinetic assessment in sports performance monitoring and biomechanical research, while offering improved accessibility through an open-source and transparent analysis framework with a hardware cost below 500 USD. Full article

High-intensity 5 km running offers an ideal framework to analyze the organism’s multidimensional responses. Since previous research primarily analyzed isolated aspects of fatigue, this study aimed to examine the integrated acute neuromuscular, metabolic, and perceptual responses to a 5 km run. Twenty-one recreational male runners participated. Pre- and post-race assessments included body composition, blood lactate, m. rectus femoris ultrasound thickness, quadriceps maximal voluntary isometric contraction (MVIC), heart rate, perceived exertion (Borg CR10), and 5 km finish time. Statistical analysis was performed in the Jamovi software, utilizing descriptive statistics, the Shapiro–Wilk test of normality, the Wilcoxon signed-rank test with effect size calculation, and Spearman’s correlation coefficient, at a significance level of p < 0.05. Post-race measurements revealed a significant decrease in quadriceps MVIC (pre: 305 ± 99 N vs. post: 259 ± 88 N; p = 0.002) and an increase in blood lactate (pre: 0.8 ± 0.4 vs. post: 6.9 ± 1.4 mmol/L; p < 0.001), alongside high average heart rates (165 ± 16 bpm). However, ultrasound-assessed muscle architecture remained unchanged. The 5 km run induced pronounced neuromuscular and metabolic fatigue. Unchanged muscle architecture suggests that acute strength decline is primarily mediated by metabolic and neural mechanisms, rather than immediate structural–morphological factors. These findings highlight the value of an integrated assessment approach for understanding acute fatigue responses following high-intensity 5 km running and may contribute to more precise training-load prescription and recovery monitoring in recreational runners. Full article