Search Results (1,444)

Background: Stroke rate (SR) is a critical determinant of swimming speed and performance; however, the relationship between upper-limb movement frequency assessed on land and SR in water remains unclear. Methods: This preliminary study examined the association between dry-land upper-limb movement frequency and in-water kinematics in ten male competitive swimmers (15.23 ± 1.06 years). Dry-land upper-limb movement frequency was evaluated through two maximum-effort trials consisting of 10–12 circular arm movements performed under a straight-arm condition (STR_SR) and a swimming-technique-simulated bend-arm condition (TECH_SR). All trials were video-recorded for analysis. In-water testing included a maximum-effort 50 m sprint and 8–12 × 25 m progressively increasing speed tests to elicit maximum swimming speed and maximum SR. SR, swimming speed, stroke length, and stroke index were calculated for all trials. Results: No relationship was observed between dry-land upper-limb movement frequency and SR of the 50 m test (p > 0.05). However, the percentage difference between STR_SR and maximum SR was associated with stroke index at maximum speed (r = −0.66, p = 0.04), maximum SR (r = −0.65, p = 0.04), and swimming speed at maximum SR (r = −0.72, p = 0.01) οf the 8–12 × 25 test. Similarly, TECH_SR was correlated with stroke index at maximum speed, SR, and stroke length in the 8–12 × 25 test (r = −0.67 to −0.71, p = 0.01). Conclusions: These findings suggest that faster and more efficient swimmers exhibit a greater difference between their maximum dry-land movement frequency in upper limbs and the SR adopted in water, allowing a greater potential to adjust in a more comfortable and submaximal manner in water movements. Full article

Background: This study examined the effects of an individualized weighted vest sprint training program on sprint performance and countermovement jump (CMJ) outcomes in post-peak height velocity (PHV) male youth soccer players while accounting for maturation status. Methods: Fifty players (mean age 17.76 ± 0.95 years) were randomly assigned to a weighted vest sprint group (WVG; n = 25) or a traditional unloaded sprint group (TS; n = 25). Sprint performance (5, 10, 20, and 30 m) and CMJ-derived variables (jump height, peak power output, reactive strength index modified (RSI-modified), and eccentric rate of force development) were assessed before and after an 11-week intervention performed twice weekly, with the WVG completing sprint drills while wearing a weighted vest (~11% body mass). Results: Weighted vest sprint training produced greater improvements in 10 m sprint performance and RSI-modified (d = 1.37 and 1.55, respectively). However, after Benjamini–Hochberg adjustment for multiple comparisons, the effects were no longer statistically significant and should therefore be interpreted with caution. Maturity offset did not meaningfully moderate training-induced adaptations. Conclusions: These findings suggest that weighted vest sprint training may provide potential benefits for mid-acceleration performance and reactive strength in post-PHV youth soccer players, although the magnitude of these effects remains uncertain. Full article

Background: Ultimate Frisbee (UF) is an intermittent team sport with distinct positional roles (cutters and handlers), yet evidence integrating anthropometric, body composition, and physical performance profiles by playing position remains limited. This study aimed to examine positional differences in these variables among male UF players. Methods: Forty male players (age: 25.13 ± 3.76 years; 7.0 ± 2.5 years of training experience) participated in this cross-sectional design, including 20 cutters and 20 handlers. Anthropometry, body composition, and dynamic balance variables were analyzed using independent-samples t-tests or Mann–Whitney U tests, as appropriate. Positional differences in somatotype and physical performance were analyzed using a one-way multivariate analysis of variance (MANOVA). Results: No positional differences were observed in general anthropometric variables (p > 0.05). However, handlers exhibited higher body fat percentage (14.32 ± 2.37 vs. 11.95 ± 2.45; p = 0.028), fat mass (11.08 ± 2.51 vs. 8.95 ± 2.67 kg; p = 0.049), and endomorphy (4.15 ± 1.22 vs. 2.99 ± 1.30; p = 0.002) than cutters. In contrast, cutters demonstrated higher speed (20 m sprint: 3.11 ± 0.17 vs. 3.21 ± 0.15 s; p < 0.05), agility (10.16 ± 0.69 vs. 10.69 ± 0.61 s; p < 0.05), and vertical jump performance (Counter Movement Jump: 40.93 ± 6.54 vs. 36.38 ± 4.71 cm; p < 0.05; Abalakov: 46.39 ± 7.88 vs. 40.20 ± 4.68 cm; p < 0.01). No differences were found in intermittent endurance (Yo-Yo Intermitent Recovery Test1): 982 ± 354 vs. 940 ± 348 m), upper-limb power, or dynamic balance. Conclusions: These findings indicate that playing position in UF is characterized by distinct body composition and lower-limb neuromuscular performance profiles, whereas intermittent endurance, upper-limb power, and balance represent shared physical requirements across positions. Full article

This study analyzes the application of the agile SCRUM methodology in the Peruvian cocoa production chain, aiming to improve organizational efficiency, bean quality, and environmental sustainability. Four experimental SPRINTS were implemented in a cocoa plantation located in San Martín, Peru, addressing practices such as the use of bio-organic fertilizers, monitoring of the fermentation process, and cadmium reduction in cocoa beans. The results showed significant physiological improvements: treatment R3 increased plant height by +10.5 cm (p < 0.005), and stem diameter reached a mean value of 11.36 mm in treated living plants compared to 6.46 mm in the untreated control group. The fermentation process remained under statistical control, with an overall mean temperature of 34.57 °C and no deviations beyond the established control limits (UCL: 50.71 °C, LCL: 18.43 °C). Regarding cadmium reduction, treatment T6 (MycoUp 3 kg/ha + MBB 2 kg/ha) reduced cadmium concentration to 0.039 mg/kg, below the maximum limit established by the European Union (0.05 mg/kg), in contrast to the control group, which reached 0.134 mg/kg. The implementation of SCRUM facilitated iterative planning, clear role allocation, and data-driven decision-making, demonstrating its adaptability to the agribusiness sector. This research proposes a replicable model that integrates technological innovation, agroecology, and collaborative management to address the structural and commercial challenges of Peruvian cocoa production. Full article

Background: Ice hockey is characterized by repeated short-duration, high-intensity efforts interspersed with brief recovery periods, requiring a complex interaction of aerobic and anaerobic energy systems. The aim of this study was to determine the energetic structure of repeated high-intensity on-ice sprint exercise in ice hockey players by quantifying the relative contributions of the oxidative, glycolytic and ATP–PCr energy systems. Methods: 14 male semi-professional ice hockey players performed the 30–15_IIT followed by the Repeated High-Intensity Effort (RHIE) on-ice. Oxygen uptake was measured breath-by-breath, blood lactate concentration and energy system contributions were estimated using a three-component PCr–La–O₂ model. Results: The RHIE on-ice was characterized by a dominant aerobic contribution (63.1 ± 2.6%), followed by phosphagen metabolism (29.8 ± 2.9%), with a relatively small glycolytic contribution (7.4 ± 1.5%). Conclusions: No significant relationships were observed between maximal oxygen uptake (VO_2max) and the RHIE performance parameters, energy system contributions or lactate responses, except for a moderate relationship between absolute VO_2max and absolute aerobic work. In contrast, parameters determined at the anaerobic threshold showed more consistent relationships with absolute metabolic work. These findings indicate that repeated high-intensity on-ice performance in ice hockey is largely independent of VO_2max and is more closely related to individual energetic profiles and metabolic tolerance. Full article

Introduction: This study investigated heart rate variability (HRV) and perceived recovery status (PRS) in relation to sprint performance in competitive athletes involved in sprint events. A secondary aim was to explore potential gender-based differences in these relationships. Methods: Fifty-six sprint-trained athletes (21 males, 35 females; age 16–21) participated in a 5-day in-season microcycle. Daily morning HRV was measured using Polar H10 chest straps and the HRV4Training app, with the root mean square of successive differences (LnRMSSD) used as the primary HRV marker. Perceived recovery was assessed each morning using the PRS scale. On each day, athletes completed 20 m maximal sprint tests. Linear mixed-effects models were used to examine the relationships between LnRMSSD, PRS, gender, and sprint performance while accounting for repeated measurements within athletes. Results: Linear mixed-effects modeling revealed that LnRMSSD was a significant negative predictor of sprint time (β = −0.019, p = 0.003), indicating that higher parasympathetic activity was associated with faster sprint performance. PRS was also a significant negative predictor of sprint performance (β = −0.014, p = 0.008). Conclusions: Daily recovery markers were associated with sprint performance in competitive sprint athletes, with potential gender-specific patterns that should be interpreted cautiously. Both LnRMSSD and PRS were significantly associated with sprint performance, highlighting the relevance of combining physiological and subjective recovery markers in athlete monitoring. Full article

Background: This study aimed, in U11 male football players, (i) to investigate the effects of an 8-week running-based HIIT or SSGs program on aerobic fitness, neuromuscular performance and internal load, and (ii) to compare training-induced changes in performance variables between training modalities. Methods: Sixteen U11 football players were randomly assigned to either the SSGs group (4 vs. 4 format, 5 × 3 min with 1 min of rest between bouts) or the HIIT group (5 × 3 min of 15 s running at 100% peak velocity (Vpeak) alternating with 15 s of recovery, and 1 min of rest between sets). The intervention period lasted 8 weeks. Aerobic fitness (Yo-Yo Intermittent Recovery Level 1 Children’s Test, YYIR1C), sprint time performance (10 m and 20 m sprints tests) and change-of-direction (COD) ability (Arrowhead Agility Test) were assessed before and after the intervention. Heart rate (HR) and rating of perceived exertion (RPE) were assessed as indices of internal load. Results: Both SSGs and running-based HIIT produced comparable improvements in YYIR1C distance, Vpeak (p < 0.05), with no significant change in the between-group difference. Neuromuscular gains occurred only after SSGs (p < 0.05), with similar 10 m sprint improvements between groups but superior 20 m gains for SSGs (p < 0.01). COD ability improved in both groups (p < 0.05), with broader enhancements following SSGs (p < 0.05). Finally, running-based HIIT elicited greater HRpeak and higher RPE than SSGs (p < 0.05) across most intervention weeks. Conclusions: In U11 male football players, both SSGs and running-based HIIT effectively improved aerobic fitness and COD performance. However, SSGs may offer additional benefits for sprint development with lower perceived psychological stress. Full article

Background: Basketball requires frequent short-distance sprints performed under both predictable (closed-skill) and unpredictable (open-skill) conditions. Objectives: This study compared sprint performance between closed- and open-skill conditions in 37 professional male basketball players aged 16–18 years. We aimed to determine whether sprint times differ between conditions and distances, test for a condition-by-distance interaction, and evaluate whether player rankings remain consistent across conditions. Methods: All players completed 5 m and 10 m sprints under both closed- and open-skill formats. Performance was analyzed using repeated-measures analysis of variance (ANOVA) for main effects and interactions, paired-samples t-tests for condition-specific comparisons, and correlation analyses to examine ranking consistency. Results: Sprint times were significantly slower in open-skill compared to closed-skill conditions at both distances (p < 0.001), indicating a clear performance decrement when responding to a visual stimulus. No significant condition-by-distance interaction was observed, despite a descriptively greater slowdown at shorter distances. Ranking consistency between conditions was low, indicating that faster closed-skill performers did not necessarily maintain their advantage in open-skill scenarios. Conclusions: These findings suggest that open-skill sprinting may reflect a distinct performance profile integrating physical acceleration and perceptual–cognitive processing. Including reactive sprint assessments in studies may enhance the sport-specific evaluation of explosive speed in basketball. Full article

The aim of the present study was to examine the potential effects of circadian rhythmicity on specific external load metrics in professional male soccer players. Twenty players, members of a Greek Super League team, participated in the study. Data were collected from twenty match-day-minus-one (MD-1) training sessions, performed either in the morning (10:30 h, n = 10) or afternoon (15:00 h, n = 10). All sessions followed identical structure, volume, and intensity, ensuring internal validity. The external load metrics examined were total distance (TD), high-speed running (HSR; >19.8 km/h), high-intensity-acceleration count (HIACC; >3 m/s²), high-intensity-deceleration count (HIDEC; <−3 m/s²), and sprint distance (SD; >25.2 km/h). Statistical analysis was conducted using paired t-tests with Bonferroni correction for multiple comparisons (α = 0.01). Our results revealed significantly higher TD, HSR, HIACC, and HIDEC values (p < 0.01) during morning sessions compared to afternoon, suggesting a diurnal pattern favoring morning performance. No significant difference was found for SD (p > 0.01) despite the observed tendency for higher morning-values. These findings support the notion that time of day influences training output and that habitual morning training may lead to improved physical performance due to training-induced adaptations. Since in elite soccer even minor changes in performance could be decisive for the outcome of a competition, accounting for circadian factors in training planning could be crucial for competition performance. Full article

Background/Objectives: Acute beetroot juice (BJ) nitrate supplementation may enhance agility and change of direction performance by increasing nitric oxide bioavailability and improving cognitive and skeletal muscle functions, thereby potentially attenuating post-sprint performance decrements. Methods: We investigated whether a single dose of BJ improves agility immediately after repeated maximal sprinting compared with a placebo (PL) in soccer players. Twenty-one male soccer players (competitive players: n = 8; recreational players: n = 13) completed a double-blind randomised crossover trial. Participants ingested 70 mL of BJ or PL; afterwards, they performed three sets of 6 × 20-m all-out sprints. Agility outcomes included simple response time (SRT), choice response time (CRT), and change-of-direction speed (CODS). Non-parametric analyses (Wilcoxon signed-rank test with effect size r) were applied. Results: Compared with PL, BJ improved CRT (BJ: 2.376 ± 0.255; PL: 2.534 ± 0.322; p < 0.001; r = 0.74; Z = −5.881) and CODS (BJ: 13.046 ± 1.512; PL: 13.651 ± 1.811; p < 0.001; r = 0.47; Z = −4.314). SRT was unchanged overall (BJ: 1.671 ± 0.195; PL: 1.707 ± 0.261; p = 0.185; r = 0.05; Z = −1.327). Conclusions: Under practical field-based conditions, acute BJ intake enhanced post-sprint agility and change-of-direction performance, particularly CRT and CODS. Full article

Objectives: This study compares linear sprint force–velocity (F–v) mechanical variables between elite Under-19 (U19) academy players and senior professional players. Methods: Thirty-eight senior players (SP; mean age 24.5 ± 4.3 y) and 214 U19 academy players (YP; mean age 17.4 ± 0.5 y) from 14 first-division club academies were tested during October 2023 using a motorized resistance device (1080 Motion). The following F–v variables were assessed: maximal theoretical force (F₀, N·kg⁻¹), maximal theoretical velocity (v₀, m·s⁻¹), maximal ratio of horizontal-to-resultant force (RF_max, %), and decrease in the ratio of forces (DRF, %). Between-group comparisons were performed using the t-test, and Cohen’s d effect sizes were reported. Results: Senior players outperformed U19 players across all F–v variables. F₀ exhibited a mean difference = 0.220 N·kg⁻¹, with a 95% confidence interval (CI) [0.056, 0.384], p = 0.0166, and d = 0.46. v₀ exhibited a mean difference = 0.560 m·s⁻¹, with a 95% CI [0.410, 0.710], p < 0.0001, and d = 1.07. RF_max exhibited a mean difference = 1.470%, with 95% CI [0.830, 2.110], p = 0.0003, and d = 0.69. DRF exhibited a mean difference = 0.260%, with a 95% CI [0.103, 0.417], p = 0.0013, and d = 0.53. Conclusions: U19 players demonstrated lower F₀, lower v₀, and reduced mechanical effectiveness compared with senior players. Regular monitoring of F–v profiles and individualized training interventions (force- or velocity-targeted) may be useful for training and monitoring strategies aimed at supporting physical preparation during the transition to senior soccer. Full article

Markerless motion capture (MMC) provides a non-invasive alternative for motion analysis; however, its validity at the standard frame rate of 25 Hz commonly used in broadcast and surveillance applications remains to be established. This study evaluated the performance of a 25 Hz multi-camera MMC workflow using consumer-grade cameras for capturing basketball-specific movements. Three highly trained male athletes completed seven tasks, including sprinting and simulated sport-specific skills, while being synchronously recorded by six MMC cameras (DJI Action 5 Pro, 25 fps) and a 10-camera Vicon system (25 Hz). Kinematic data were processed using an RTMDet–RTMPose pipeline and low-pass filtered at 6 Hz. Waveform validity was assessed using Pearson’s correlation coefficient (r) and the root mean square error (RMSE). The displacement magnitudes of 12 joints showed excellent agreement (r = 0.916–0.994; median nRMSE = 0.54–1.32%), indicating robust trajectory reconstruction. In contrast, agreement decreased for derivative variables: velocity (r = 0.583–0.867) and acceleration (r = 0.232–0.677) were highly sensitive to the low sampling rate and numerical differentiation. Although a 25 Hz configuration is insufficient for high-precision impact analysis, it provides acceptable accuracy for macroscopic displacement tracking and external-load quantification in resource-constrained training environments. Future optimization should prioritize temporal synchronization to improve the reliability of derivative variables. Full article

Background: This study investigated sex-based differences in sprint performance and fatigue among 9–14-year-olds using two repeated-sprint protocols: the Muscle Power Sprint Test (MPST; 6 × 15 m) and the Children’s Repetitive Intermittent Sprint Performance test (CRISP; 6 × 30 m). Additionally, four fatigue metrics were compared: decay (first vs. last sprint), fatigue index (fastest vs. slowest sprint), sprint decrement (ideal vs. actual total time), and slope IP (regression slope across all sprints). Methods: A total of 140 children (9–14 years; 70 females, 70 males) performed the two tests in randomized order. They completed the six sprints per test with 10 s of recovery between each sprint of either 15 or 30 m. Fatigue metrics were calculated for each test based on the sprint times. Results: Running speed was higher in CRISP than in MPST, and males outperformed females in both tests. In the MPST, fatigue metrics did not differ significantly by sex. In contrast, all fatigue indices in CRISP were significantly greater in females, indicating higher fatigue despite slower sprinting compared to males. Among the fatigue metrics, slope IP correlated most strongly with decay, while associations with fatigue index and sprint decrement were weaker. Conclusions: Fatigue assessment is more sensitive over longer sprint distances. Females demonstrated significant fatigue in CRISP, indicating that fatigue is task-dependent. The slope metric, which incorporates all sprints, offers a robust fatigue measure for group comparison, while decay remains a practical alternative for field settings. Full article

Background: Age-related differences in neuromuscular coordination during multi-joint tasks are reported, but phase-specific evidence during maximal sprinting is limited. Aim: The aim of this study was to investigate phase-specific age differences in agonist–antagonist coordination of the biarticular thigh muscles during 50 m sprinting. Methods: Thirty-eight healthy trained track athletes (Adults: n = 21, age = 23.32 ± 2.98 years; Adolescents: n = 17, age = 13.65 ± 0.76 years) performed maximal 50 m sprints over force plates. Bilateral rectus femoris (RF) and biceps femoris (BF) sEMG and ground reaction forces were recorded; each stride was segmented into seven phases, and an RF–BF co-contraction index (CCI) was calculated per phase. Between-group differences in phase mean CCI were tested (α = 0.05) and quantified with Hedges’ g. Speed- and frequency-dependent modulation of CCI was evaluated using linear mixed-effects models (LME; random intercepts for participant) with Frequency × Group and Speed × Group interaction terms; ordinary least squares (OLS) fits on stride cycle-level group means were descriptive. Linear and single-breakpoint segmented models were compared using the corrected Akaike information criterion (AICc) and Akaike weights. Results: Adolescents showed higher CCI in contact (right: Adults 0.09 ± 0.05 vs. Adolescents 0.13 ± 0.07, g = 0.68; left: Adults 0.08 ± 0.04 vs. Adolescents 0.12 ± 0.06, g = 0.84) and propulsive phases (right: Adults 0.08 ± 0.05 vs. Adolescents 0.13 ± 0.08, g = 0.68; left: Adults 0.07 ± 0.04 vs. Adolescents 0.12 ± 0.07, g = 0.84; p < 0.05 for both legs in both phases). LME identified Frequency × Group interactions in the stride cycle (ΔSlope = 0.10, p < 0.001) and late swing (ΔSlope = 0.12, p < 0.05) and a Speed × Group interaction in mid swing (ΔSlope = 0.01, p < 0.05). Mid swing showed a positive CCI–speed/frequency relationship in both groups, whereas across most other phases Adults downregulated CCI as speed/frequency increased while Adolescents tended to increase CCI. Model selection supported phase-dependent single-breakpoint patterns, with breakpoints around 2.19–2.21 Hz and 6.11–9.51 m·s⁻¹ in Adults and around 2.11 Hz and 7.13–7.59 m·s⁻¹ in Adolescents. Conclusions: Maximal sprinting revealed phase-specific age differences in BF–RF co-contraction and its scaling with speed/frequency, which may help guide age-informed monitoring and training considerations in developing athletes. Full article

Background: This systematic review aimed to analyze and synthesize the available evidence on the neuromuscular profile of female futsal players. Methods: The review was conducted in accordance with PRISMA guidelines and registered with PROSPERO (CRD420251055503). PubMed, Scopus and SPORTDiscus databases were searched until May 2025. The eligibility criteria were defined using the PECOS strategy. The methodological quality of the included studies was evaluated using the Downs and Black modified version. Results: Twenty-three studies were included, covering a total of 433 female players between the ages of 12 and 27. Muscle strength was assessed mainly using an isokinetic dynamometer, jumping ability using the countermovement jump and squat jump, sprinting using the 10 m, 20 m and 30 m tests and agility and change of direction (CoD) using the Illinois agility test. Elite players generally showed a better performance in agility and CoD tests compared to lower-level players. Conclusions: This review provides a comprehensive overview of the neuromuscular profile of female futsal players and highlights trends related to the competitive level. These findings may support evidence-based practices for performance evaluation, training and injury prevention. More studies are needed to standardize methods and understand differences between competitive levels. Full article