Search Results (979)

Background: CrossFit^® has gained widespread popularity as a high-intensity training modality, yet evidence describing neuromuscular performance characteristics in this population remains limited. This study aimed to evaluate isometric and ballistic strength profiles in trained CrossFit^® athletes and to identify sex-based differences in absolute and relative neuromuscular performance. Methods: Seventy-two athletes participated (41 males and 31 females) participated in the study, completing two maximal isometric mid-thigh pull (IMTP) tests and three countermovement jump (CMJ) tests within a single testing session. Assessments were conducted using a dual force plate system (Hawkin Dynamics, Westbrook, ME, USA). Results: In the IMTP, males exhibited substantially higher absolute isometric force outputs, including peak force (3059 ± 576 vs. 1899 ± 324 N; p < 0.001) and relative peak force (36.34 ± 6.74 vs. 30.99 ± 4.41 N/kg; p < 0.001). Rates of force development were also greater in males for both early (0–50 ms: 7665 ± 5420 vs. 4001 ± 3021 N/s; p < 0.001) and late phases (0–250 ms: 5350 ± 1832 vs. 3035 ± 886 N/s; p < 0.001). However, no significant sex differences were detected in time to peak force (2.31 ± 1.27 vs. 1.94 ± 1.04 s) or dynamic strength index (0.72 ± 0.12 vs. 0.73 ± 0.12 a.u.). In ballistic performance using CMJ, males achieved higher jump height (0.33 ± 0.07 vs. 0.23 ± 0.05 m; p < 0.001), jump momentum (215 ± 27.9 vs. 131 ± 19.1 kg·m/s; p < 0.001), and modified reactive strength index (0.46 ± 0.11 vs. 0.32 ± 0.08 a.u.; p < 0.001). Relative propulsive and braking forces were also moderately greater in males. Notably, sex differences were reduced when variables were normalized to body mass or peak force, indicating comparable relative neuromuscular function across sexes. Conclusions: These findings provide descriptive neuromuscular performance data for CrossFit^® athletes and show that sex-based differences primarily reflect disparities in absolute force-production capacity rather than intrinsic neuromuscular efficiency. Such insights may support more precise, evidence-informed, and sex-specific training prescriptions to optimize performance. Full article

This study developed a biomimetic jumping robot inspired by frogs to enhance its obstacle-crossing capabilities. The biological principles underlying the jumping biomechanics of frog hindlimbs were integrated into the robotic mechanism; quantitative analysis of the bionic structure and its jumping performance not only provides mechanical engineering insights for investigating frog locomotion mechanics but also offers practical design references for the development of biomimetic mobile robots. Through theoretical calculations and application scenario analysis, a six-bar linkage mechanism was designed to simulate the force generation of frog hindlimbs, with tension springs mimicking the elastic energy storage function of the semimembranosus and gastrocnemius muscles. A reducer was integrated into the trunk to enable energy storage, and an adjustable single-hinge structure was adopted for the forelegs to realize take-off angle adjustment and shock absorption. Finite element simulations were conducted to validate the load-bearing capacity and strength of critical components. Multi-body dynamics and the particle swarm optimization (PSO) algorithm were employed to explore the relationship between input parameters and output performance metrics (jumping height and jumping distance), while orthogonal experimental analysis was used for comprehensive parameter evaluation. Finally, a physical prototype was fabricated, and its performance parameters were tested. The prototype has a mass of 150 g, generates a ground push force of 50 N, attains a jumping height of 380 mm, and achieves a maximum jumping distance of 500 mm. This study establishes a biologically inspired working principle for jumping robots and provides a novel practical prototype for research into biomimetic mobile robots. Full article

Background/Objectives: Physical literacy (PL) is globally recognized as a foundational determinant of health status in children, but the effects of interventions based on PL were rarely studied in preadolescent children. The aim of this quasi-experimental, school-based study was to evaluate the potential effects of a PL intervention delivered during regular school hours on physical fitness (PF), physical literacy (PL), and physical activity (PA) in children aged 9 to 11 years from southern Croatia. Methods: Participants were 125 preadolescents (57 girls), and were grouped into a control group (C = 70), and an experimental group (E, n = 55). The E group participated in a specific PL-focused education, integrated into regular physical education (PE) lessons as a 5–6 min substitute for standard PE content, over 12 weeks (36 PE classes in total). The C group participated in the standard PE curriculum. A pre–post–retention design was used, and the observed variables included anthropometrics (height, weight, BMI), PF (jumping power, abdominal strength, upper body strength, flexibility, mobility, and cardiovascular endurance), PL (evaluated by the PLAYself questionnaire), and indirectly measured PA (estimated via the PAQ-C questionnaire). Multivariate (MANOVA and univariate (ANOVA) analyses of variance for repeated measurements were used with time, gender, and group as the main effects, including their interactions. Results: MANOVA calculated for a set of PF variables revealed significant main effects for time (F = 1361, p < 0.001) and a significant time × group interaction (F = 2.98, p < 0.05). Univariate ANOVA indicated specific intervention effects for jumping power and abdominal strength, favoring the E group. No significant differential effects were observed for PL or PA. Conclusions: The study demonstrated small, but statistically significant, improvements in PF indicators among children exposed to the PL-based intervention. Notably, the intervention was conducted in authentic school settings using standard resources, supporting the ecological validity and real-world applicability of the findings. Full article

Background: This study compares the effects of relativized barbell loads (% of one-repetition maximum or 1RM) versus standardized prescribed loads on High-Intensity Functional Training (HIFT) performance, strength adaptations, physiological response, and perceived effort. Methods: In total, 22 experienced HIFT athletes (12 males, 10 females) were randomly assigned to either a standardized load (SL) or relativized load (RL) group. Both groups completed an 8-week HIFT program with benchmark workouts. Performance was assessed using a local muscle endurance test, maximal strength through 1RM testing (back squat, clean, and clean and jerk), and neuromuscular performance via countermovement jump (CMJ). Cardiopulmonary response (VO²peak, VO²mean, heart rate, and blood lactate levels) and perceived effort (Borg CR-10) were also evaluated. Results: RL participants did not show a difference in the interaction between group and time in TT performance but differences were founded for strength gains in back squat (p = 0.005, 95% CI [3.1, 8.6]) and clean (p = 0.027, 95% CI [1.2, 5.7]) compared to the SL group. No significant differences were found in clean and jerk performance or CMJ height. Cardiopulmonary responses were similar between groups, indicating comparable physiological stress. RL participants reported significantly lower perceived exertion (p < 0.001, 95% CI [6.3, 9.8]), suggesting more efficient load management and recovery. Conclusions: Use of individualized loads based on 1RM enhanced HIFT performance and strength adaptations, without increasing physiological stress, enabling more efficient training with reduced fatigue. Full article

Background: Beach volleyball is a high-intensity, intermittent sport requiring repeated explosive actions and rapid changes of direction performed on an unstable sand surface. Creatine monohydrate (CrM) supplementation has consistently been shown to enhance short-duration, high-intensity performance; however, evidence in female athletes and sport-specific contexts in beach volleyball remains limited. The purpose of this study was to examine the effects of CrM supplementation delivered in gummy form on physical performance outcomes, body composition, and reaction time in female beach volleyball athletes. Methods: Thirty-two female collegiate and professional beach volleyball athletes completed a 10-week randomized controlled trial and were assigned to either CrM, 5 g·day⁻¹ group (n = 17) or control group (n = 15). Countermovement jump (CMJ) height, change-of-direction speed (CODS), body composition, and reaction time were assessed before and after the intervention. Outcomes were analyzed using mixed-model analyses of variance. Results: Significant Group × Time interactions were observed for CMJ height and CODS, with the CrM group demonstrating improvements in jump height (p < 0.001, ηp² = 0.34) and faster change-of-direction performance (p = 0.009, ηp² = 0.21), while the control group showed no improvement or performance declines. Significant Group × Time interactions were also observed for body fat mass (p = 0.024, ηp² = 0.16), body fat percentage (p = 0.015, ηp² = 0.18), and total body water (p = 0.038, ηp² = 0.14). No significant interactions were observed for lean body mass, skeletal muscle mass, total body mass, or reaction time. Conclusions: CrM supplementation delivered in gummy form enhanced selected performance outcomes and helped maintain body composition in female beach volleyball athletes. These findings support creatine gummies as a practical supplementation strategy in this population. Full article

Objective: We examined vastus lateralis (VL), gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and biceps femoris (BF) muscle architecture and force–time parameters recorded during a countermovement jump (CMJ). Methods: Eighty-nine 9 year-old girls (43 rhythmic gymnasts and 46 recreationally active controls) were assessed in: (a) muscle architecture (fascicle length—FL; angle; muscle thickness; and anatomical cross-sectional area—CSA) using ultrasonography, (b) CMJ performance (maximum force—Fmax; rate of force development—RFD; jump height; and peak power) using force–time data, and (c) anthropometrics and body composition. Results: Rhythmic gymnasts exhibited greater BF fascicle length and muscle thickness than controls (7.84 ± 0.73 vs. 7.26 ± 0.75 cm and 1.76 ± 0.19 vs. 1.61 ± 0.22 cm, respectively, p < 0.001), while VL muscle CSA was larger in controls (p = 0.001). When normalized to the respective segment length (thigh or shank), the FL was longer in gymnasts across all muscles (p ≤ 0.017). Gymnasts also demonstrated greater CMJ height (13.1%, p = 0.005), power scaled to body mass, and RFD (p < 0.005), while controls produced a greater Fmax (16.9%, p = 0.002). Body mass was the strongest predictor of Fmax in both groups (p < 0.001). CMJ power was best predicted by gastrocnemius CSA in gymnasts and by VL CSA combined with maturity offset in controls (all p < 0.001). Maturity offset and gastrocnemius CSA also predicted allometrically scaled power in controls. Conclusions: Rhythmic gymnasts are characterized by muscle-specific adaptations, specifically in the BF muscle FL and muscle thickness, which favor superior CMJ performance. In developing athletes, body mass is primarily related to maximal force, whereas muscle CSA is more closely associated with power output. Full article

Performance differences between female youth handball players selected for national teams and non-selected peers are often linked to strength, speed, and power. This study aimed to compare the conditioning capacities and body composition of national and non-national youth handball players. The sample included 36 female players (17.13 ± 1.75 years), 18 national and 18 position-matched non-national players. Anthropometry, sprint and change in direction ability, vertical jump, upper- and lower-body strength, aerobic capacity, and body composition were assessed using standard tests and bioimpedance analysis. For normally distributed variables, an independent-samples t-test was applied, while for variables that did not meet the normality assumptions, the Mann–Whitney U test was used. Cohen’s d was used to assess effect size. National team players showed significantly greater jump height (p < 0.001, d = 1.408), higher relative peak power (p < 0.001, d = 1.644), and faster 20 m sprint times (p = 0.004, d = −1.037). No significant differences were found in body composition or the other measured parameters, although a moderate Yo-Yo IRL1 effect size suggests a potential practical advantage in aerobic capacity for national team players. These results indicate that explosive power and linear speed are key discriminators for youth national-team selection. Full article

Background and Objectives: Percussive massage devices (PMDs) are increasingly used as warm-up tools to enhance neuromuscular performance; however, evidence regarding the optimal intensity and its interaction with circadian variation remains limited. This study examined the acute effects of two percussive massage intensities (low: 28 Hz; moderate: 35 Hz) compared with no massage on change-of-direction (COD) performance, vertical jump kinetics, and neuromuscular variables in trained male football players across morning and evening sessions. Materials and Methods: Eighteen trained male football players completed a randomized, counterbalanced crossover design involving three protocols (no massage, 28 Hz, and 35 Hz) performed in both morning (09:00–11:00) and evening (17:00–19:00) sessions following a standardized warm-up protocol. COD performance (T-Test and Illinois COD Test), countermovement jump height, and model-derived kinetic variables were assessed. Results: Significant main effects of the protocol were observed for T-test performance, jump height, velocity-related variables, and kinetic outcomes (p < 0.001; large effect sizes), with both percussive massage intensities outperforming the no-massage condition. Significant protocol × time-of-day interactions emerged for jump height, force, and impulse-related variables (p < 0.05), indicating greater morning-specific benefits following moderate-intensity (35 Hz) massage. The Illinois COD Test showed no significant protocol-related changes. Conclusions: Acute percussive massage enhances COD performance and vertical jump-related outcomes in trained football players. While both intensities are effective for general performance enhancement, moderate-intensity massage (35 Hz) appears to be more effective for optimizing force–time characteristics and attenuating morning-related performance decrements. These findings support the inclusion of intensity- and time-specific percussive massage strategies in warm-up routines. Full article

This study compared force plate-derived lower-limb strength and power metrics between selected and non-selected female basketball players for major international competitions. Thirty-two female players attending the final national team camps for the 2022 World Cup and the 2024 Olympic Games completed isometric mid-thigh pull (IMTP) and countermovement jump (CMJ) testing on dual force plates (1000 Hz). IMTP peak force, rate of force development (RFD) over 0–200 and 0–250 ms, CMJ height, and phase-specific kinetic variables were compared between roster (n = 14) and non-roster (n = 18) players. Eleven roster players had previous World Cup/Olympic experience (1.5 ± 1.2 selections across all 14 players), whereas non-roster players had none. The roster group was older than the non-roster group (26.8 ± 4.2 vs. 22.3 ± 3.1 years, p = 0.002); therefore, between-group comparisons were adjusted for age and playing position using analyses of covariance (ANCOVAs). After adjustment, no between-group differences were observed in IMTP- or CMJ-derived performance outcomes (all p ≥ 0.12; partial η² = 0.00–0.09). Therefore, in this elite cohort, roster status did not reflect force plate metrics but may reflect factors beyond these tests, including age and prior international experience. Full article

Background: In soccer, the repeated execution of unilateral actions may lead to uneven limb development, promoting the occurrence of asymmetries. However, there is no consensus on the impact of these asymmetries on sports performance or the influence of playing position on their magnitude. Methods: A cross-sectional study was conducted with 33 male federated soccer players (age: 18.42 ± 4.24 years; body mass: 70.23 ± 8.74 kg; height: 1.76 ± 0.07 m; body mass index: 22.6 ± 2.7 kg/m²). Hamstring strength asymmetry between the dominant and non-dominant limbs was assessed using functional electromechanical dynamometer (FEMD) at eccentric velocities of 0.4, 0.8, and 1.2 m/s. Physical performance was evaluated through a 30 m sprint and countermovement jump (CMJ). Differences according to playing position were also analyzed. Results: Significant between-limb differences were found in strength, power, and impulse, with effect sizes increasing as testing velocity rose. No significant differences in asymmetry levels were observed across playing positions, and no correlations were found between hamstring asymmetry and physical performance outcomes. Conclusions: Although functional lower-limb asymmetries were identified in soccer players, these asymmetries did not directly influence performance nor vary across playing positions. The findings suggest that certain asymmetries may represent normal functional adaptations in soccer rather than pathological structural imbalances. Full article

Background: Basketball performance depends strongly on physical preparation. A novel approach is accentuated eccentric loading within contrast training, though its acute effects using dumbbells remain underexplored. Methods: Twelve youth basketball players (age = 16.0 ± 0.3 years; body mass = 81.5 ± 7.6 kg) completed three sessions with dumbbell loads equivalent to 15%, 30% and 45% BW. CMJ performance was measured using dual wireless dual force plates. Assessments were conducted before the protocol and at 3, 9, and 15 min post intervention. Subjective responses were collected via wellness, RPE and readiness questionnaires. A two-way repeated measures ANOVA with Bonferroni corrections was applied, and the significance level was set to α = 0.05. Results: Significant decreases in jump height (p = 0.010) and average propulsive power (p = 0.005) were observed in the 45% BW condition at 3 and 9 min. Jump momentum decreased significantly at 30% and 45% BW at 3 and 9 min (p = 0.010; p = 0.033). No significant differences were detected in other CMJ force–time metrics (p > 0.05). Conclusions: Dumbbell-loaded CMJs as an accentuated eccentric loading contrast exercise did not produce generalized improvements but induced acute decreases at higher loads. However, they may still be useful in individual cases for athletes with favorable responses after monitoring. Full article

Background/Objectives: Transcranial direct current stimulation (tDCS) is increasingly used by athletes, yet sport-performance-enhancement findings are mixed and often small, with outcomes depending on stimulation target, timing, and task demands. Aim: This scoping review mapped and synthesized the soccer-specific trial evidence to identify (i) which tDCS targets and application schedules have been tested in soccer players, (ii) which soccer-relevant outcomes show the most consistent immediate (minutes–hours) or training-mediated benefits, and (iii) where evidence gaps persist. Methods: We conducted a scoping review of clinical trials in footballers, following review best-practice guidance (PRISMA-informed) and a preregistered protocol. Searches (August 2025) spanned PubMed/MEDLINE, ResearchGate, Google Scholar, and Cochrane, using combinations of “football/soccer” and “tDCS/transcranial direct current stimulation,” with inclusion restricted to trials from 2008–2025. Dual independent screening was applied. Of 47 records identified, 21 studies met the criteria. Across these, the total N was 593 (predominantly male adolescents/young adults; wide range of levels). Results: Prefrontal protocols—most commonly left-dominant dorsolateral prefrontal cortex (DLPFC) (+F3/−F4, ~2 mA, ~20 min)—most consistently improved post-match recovery status/well-being (e.g., fatigue, sleep quality, muscle soreness, stress, mood), and when repeated and/or paired with practice, shortened decision times and promoted more efficient visual search. Effects on classic executive tests were inconsistent, and bilateral anodal DLPFC under fatigue increased risk-tolerant choices. Motor-cortex targeting (C3/C4/Cz) rarely changed rapid force–power performance after a single session—e.g., multiple well-controlled trials found no immediate CMJ gains—but when paired with multi-week training (core/lumbar stability, plyometrics, HIIT, sling), it augmented strength, jump height, sprint/agility, aerobic capacity, and task-relevant EMG. Autonomic markers (exercise HR, early HR recovery) showed time-dependent normalization without specific tDCS effects in single-session, randomized designs. In contrast, a season-long applied program that added prefrontal stimulation to standard recovery reported significantly reduced creatine kinase. Across studies, protocols and masking were athlete-friendly and rigorous (~2 mA for ~20 min; robust sham/blinding), with only mild, transient sensations reported and no serious adverse events. Conclusions: In soccer players, tDCS shows a qualified pattern of benefits that follows a specificity model: prefrontal stimulation can support post-match recovery status/well-being and decision efficiency, while M1-centered stimulation is most effective when coupled with structured training to bias neuromuscular adaptation. Effects are generally modest and heterogeneous; practitioners should treat tDCS as an adjunct, not a stand-alone enhancer, and align montage × task × timing while monitoring individual responses. Full article

Background: Force plate-derived metrics are increasingly used to assess performance and monitor musculoskeletal injury risk, yet the mechanisms linking jump-mechanics patterns to injury risk remain unclear, particularly when using proprietary, algorithmically derived risk scores. Clarifying these relationships is important for improving screening practices, program design, and load management in athletic populations. Methods: A total of 233 collegiate athletes completed countermovement vertical jump (CMVJ) testing on a commercial force plate, which produced 26 force-time variables and proprietary composite metrics. LASSO regression with bootstrapping identified important predictors of CMVJ height and algorithmically derived musculoskeletal injury (AMSKI risk), and Partial Least Squares (PLS) models characterized multivariate patterns across force-time variables. Sex-stratified analyses and post hoc modeling examined potential mechanisms. Results: Greater AMSKI risk was associated with a coordinated pattern of greater concentric output, including greater power, velocity, and impulse, combined with reduced braking capacity. Braking rate of force development (“Load”) showed an inverse association with AMSKI risk across sexes, and females in the elevated-risk category displayed significantly reduced braking values. Postural control measures contributed differently by sex. PLS models indicated that both CMVJ height and AMSKI risk reflected interactions among multiple variables, while proprietary composite scores showed inconsistent alignment with mechanistic predictors. Conclusions: Multivariate force-time profiling offers practical value for identifying athletes whose high-output movement strategies may elevate injury risk when braking control is insufficient. Because proprietary, algorithmically derived risk metrics show inconsistent associations with underlying mechanics, further independent validation is needed before such scores are used in clinical or training decisions. Full article

Background/Objectives: In Rhythmic Gymnastics (RG), the jump is an element of great difficulty that requires the qualities of strength and coordination. Jump height and power are the variables normally used to assess the final performance of jumps. However, they do not allow us to analyze what happens in the intermediate stages or provide practical information to find jump improvement strategies. This study aimed to determine which kinetic variables, organized within a hierarchical model, serve as performance indicators in the Pike Jump executed from a standing start with arm swing. Methods: Ten high-level women gymnasts (14 ± 0.7 years) performed 53 Pike Jumps on a Dinascan-IBV, v.8.1 dynamometric platform (Valencia, Spain) that recorded at 1000 Hz. In the model, jumping was divided into five phases, and 76 related efficacy variables were defined, with 34 of them normalized for total jump time or body weight. Bivariate correlations were analyzed with a bilateral significance test to validate the proposed model. Results: Average and Initial Vertical Ground Reaction Force can be used as performance indicators of the Pike Jump, providing information on intermediate stages of the jump and allowing us to improve specific aspects related to the level of force and the way to apply it in RG. Conclusions: The degree of correlation found among the variables allowed us to validate the model. Normalized variables allow a more precise analysis to be carried out and question some results obtained in the literature in which non-normalized data were presented. Full article

Jump height (JH) is widely used as an indicator of athletic performance. This study aimed to (1) evaluate the relative importance and predictive value of JH for neuromuscular performance across key physical metrics and (2) describe the neuromuscular profile of soccer players from different age groups, positions, and competitive levels. Senior (SG) and youth (YG) players were evaluated after the off season for neuromuscular power, strength, change of direction, speed, repeated sprint ability, and aerobic endurance. SG outperformed YG in most measures, especially JH, abduction strength, and Peak Power (RAST PP). Notably, YG exhibited higher maximal oxygen uptake (VO2max) and lower fatigue index (RAST FI), highlighting their robust aerobic capacity and greater ability to sustain repeated efforts. These results reinforce established developmental patterns, with aerobic endurance more pronounced in youth and anaerobic power in seniors. In seniors, JH correlated moderately with sprint and anaerobic power, while its associations in youth were weaker and linked to endurance. Positional analysis suggested overall higher JH in SG. JH emerged as a practical predictor for physical performance monitoring in seniors and a useful benchmark for athletic potential identification. Findings support targeted training and monitoring based on age-specific profiles. This study enhances applied sports science, underscoring the need for tailored approaches in player development and evaluation. Full article