Journal of Sports Science and Medicine最新文献

This study examined the impact of weekly eccentric overload training (EOT) on locomotor and mechanical performance during small-sided games (SSGs) in elite youth soccer players. A total of 22 elite male youth soccer players participated in this study. A controlled, non-randomized study design was employed. Players were assigned to either an eccentric overload training group (EOT, n = 9) or a control group (CON, n = 13). The EOT group incorporated one additional eccentric training session into their regular regimen, while the control group maintained their standard training schedule throughout the 8-week study. The Eccentric Overload Training (EOT), known for its benefits in injury prevention and performance enhancement, incorporated five exercises using flywheel devices: K-box squats, split squats, dynamic forward and backward lunges, and unilateral hamstring kicks on the Versa-Pulley. A total of 1,117 small-sided game (SSG) observations were analyzed (EOT = 528, CON = 589). No significant differences were found in locomotor variables, including zScore for total distance covered (TD), high-speed distance (HSD), very high-speed distance (VHSD), and sprint distance (SD). However, the intervention group showed lower acceleration (ACC) and deceleration (DEC) compared to controls (p < 0.05). Player load (PL) varied significantly between groups and over time (p < 0.05). These findings suggest that incorporating a weekly eccentric overload training (EOT) session may enhance locomotor performance despite temporary reductions in mechanical performance in elite youth soccer players. The practical application of the study is that minimal preventive eccentric work can be added into the intervention process without compromising physical performance capacity during that period.

While motor and technical skills are typically assessed through field-based soccer tests, cognitive skills are usually evaluated in controlled laboratory environments. The Skills.Lab Arena is a newly developed testing and training device that enables motor, technical, and cognitive assessments in a soccer-specific setting. This study evaluated the reliability and usefulness of the Skills.Lab Arena technology. In a test-retest design (7 days, 1 month), 31 young soccer players (age, 13.5 ± 0.5 years) performed 10 trials of technical and motor-cognitive tests. Absolute and relative intersession reliability were determined using the intraclass correlation coefficient (ICC) and coefficient of variation (CV). Bland-Altman analysis was used to assess agreement, mean differences, and limits of agreement (LoA). A repeated-measures ANOVA was applied to identify potential learning effects between test sessions. The smallest worthwhile change and typical error (TE) were calculated to assess the intersession usefulness of the tests. The Skills.Lab Arena tests demonstrated good relative and absolute intersession reliability, with ICC values ranging from 0.75 to 0.89 for time-based tasks and 0.71 to 0.91 for accuracy-based tasks. Bland-Altman analysis revealed minimal mean differences with acceptable 95% LoA. CV values ranged from 1.78% to 4.5% for time-based tasks and were slightly higher, ranging from 8.08% to 19.87%, for accuracy-based tasks. Learning effects were observed in one ball-related agility test. In light of the results, the Skills.Lab Arena can be considered a reliable diagnostic tool for assessing motor-cognitive performance in young soccer players. However, despite its reliability, further validation is needed before it can be recommended for practical use.

This study aimed to evaluate the impacts of a 4-week transcranial direct current stimulation (tDCS), balance training (BT), and an integrated program combining tDCS with BT on static and dynamic postural control in athletes suffering from chronic ankle instability (CAI); as well as to explore whether the combined program produces superior effects compared to either single intervention. Forty athletes with CAI were randomized into four groups: tDCS group, sham tDCS (s-tDCS) group, tDCS + BT group, and s-tDCS + BT group. Twenty minutes of 2 mA anodal or sham tDCS was applied either independently or in conjunction with a 20-minute progressive hop-to-stabilization balance (PHSB) training program over 12 supervised sessions spanning 4 weeks. Primary outcomes were the total score of the Balance Error Scoring System (BESS) and the composite reach distance (COMP) in the Y-Balance Test (YBT). Secondary outcome measures included error scores of single-limb and tandem stance on firm and foam surfaces, as well as mean normalized reach distances in the anterior (ANT), posteromedial (PM), and posterolateral (PL) directions. Compared to baseline measures, the tDCS, tDCS + BT, and s-tDCS + BT groups scored fewer errors on posttest measures for single-leg stance on a firm surface (Sfi), single-leg stance on a foam surface (Sfo), tandem stance on a firm surface (Tfi), tandem stance on a foam surface (Tfo), and the total BESS (p < 0.05). Additionally, both the tDCS + BT and the s-tDCS + BT groups showed greater PM, PL, and COMP in posttest measures compared to pretest measures (p < 0.05). However, no significant differences were found among the tDCS group, the tDCS + BT group, and the s-tDCS + BT group in the posttest measures (p > 0.05). tDCS, BT, and the combination of these two interventions can significantly improve static postural stability in athletes with CAI. However, only intervention methods incorporating BT were effective in enhancing dynamic stability. The combined program offered no additional benefits.

Identifying strategies to mitigate the impact of the Relative Age Effect (RAE) on the development of youth basketball players is crucial. This study aimed to compare two methods of player grouping during competitive small-sided games and match scenarios in training sessions, focusing on their impact on physical performance and technical skill development: mixed birthdate quartiles (CON) versus structured grouping based on birthdate quartiles (BG) over a 6-month period. A randomized controlled trial was conducted with forty-one youth basketball players (age: 12.9 ± 0.7 years) at a trained/developmental level. Throughout the study, participants in the BG group (n = 20) were assigned to small-sided games or match competition scenarios based on their birthdate quartiles, while those in the CON group (n = 21) were grouped with players from mixed quartiles. Players were evaluated at baseline and after the 6-month period for physical performance using countermovement jump (CMJ), change-of-direction (COD), and aerobic capacity (YYIRT). Additionally, they were assessed for technical skills in shooting, passing, and dribbling tests. Comparisons were made based on both birthdate quartiles (quartiles q1-2 relatively older, and q3-4 relatively younger players) and group. After 6 months, the CONq3q4 covered a shorter YYIRT distance than the CONq1q2 group (p = 0.040), achieved a lower CMJ height than both the CONq1q2 (p = 0.024) and BGq1q2 groups (p = 0.019), and had a greater COD deficit than the CONq1q2 group (p = 0.046). Additionally, the CONq3q4 group had longer dribbling times than the CONq1q2 (p = 0.002), BGq1q2 (p = 0.004), and BGq3q4 (p = 0.009) groups. In skill assessments, the CONq3q4 group scored lower in passing than both the CONq1q2 (p = 0.015) and BGq1q2 groups (p = 0.025), and scored lower in shooting compared to the CONq1q2 (p = 0.019), BGq1q2 (p = 0.003), and BGq3q4 (p = 0.003) groups. Grouping youth basketball players based on birthdate quartiles during training can mitigate the relative age effect, promoting more equitable physical and technical development by reducing age-related biases. However, these conclusions are limited by the study's duration and require further research over the long term.

Maximal strength assessment, particularly the one-repetition maximum (1RM) test, is essential in resistance training and sports science. Velocity-based metrics like mean concentric velocity (MCV) at 1RM and load-velocity profiling enhance neuromuscular monitoring, yet the stability of parameters such as load-velocity slope (VL-Slope) and peak power position (PP-Position) over repeated tests remains uncertain. Thus, 14 resistance-trained male participants (age: 25.2 ± 3.3 years; training experience: 2.1 ± 2.0 years) performed five 1RM tests in the squat and bench press over a seven-week period. Strength and velocity parameters, including 1RM, MCV at 1RM, VL-Slope, and PP-Position, were assessed using an inertial measurement unit. A repeated-measures ANCOVA was conducted to analyze changes over time, with effect sizes quantified using partial eta squared (ηp²) and standardized mean differences (SMD). No significant training-induced adaptations were observed for 1RM or MCV at 1RM across all testing sessions (p > 0.05). VL-Slope and PP-Position remained stable, indicating no systematic changes over time. However, exercise-specific differences were found, with higher absolute loads and velocities in the squat compared to the bench press. Additionally, PP-Position was significantly higher in the squat, suggesting that peak power output occurs at a higher relative load for lower-body exercises. Repeated 1RM testing does not appear to induce relevant strength or velocity adaptations over time. Coaches and practitioners should consider exercise-specific differences in force-velocity characteristics when designing training programs and interpreting performance diagnostics.

This study presented a systematic review of recent advancements in the application of finite element (FE) methods to running and running shoe biomechanics. It focused on outlining the general approach to build foot-running shoe FE models, exploring their current applications and challenges, and providing directions for future research. The review also aimed to highlight the gap between theoretical mechanical responses in simulations and real-world manifestations of running-related musculoskeletal injuries (RRMI). A comprehensive search of electronic databases, including Web of Science, PubMed, and Scopus, identified 12 eligible articles for inclusion in this review. Current studies have examined the effects of various running shoe design features and conditions on the mechanical response of internal foot tissues using foot-running shoe FE models. These models have gradually evolved from simplified local representations to more realistic and comprehensive models, with the incorporation of experimental data enhancing simulation accuracy. However, to further improve simulation outcomes, key advancements are proposed to reduce development time and enhance model robustness. These include high-fidelity 3D model development, personalized shape transformation, AI-driven automated reconstruction, comprehensive dynamic running simulations, and improved validation methods. More importantly, future research needs to bridge the gap between FE simulations and RRMI risk by addressing the complexities of bone fracture criteria and conducting localized assessments of bone properties. Overall, this review provided valuable insights for biomedical engineers, medical professionals, and researchers, facilitating more accurate investigations of foot-running shoe FE models. Ultimately, these advancements aim to improve footwear design and training programs to reduce the risk of RRMI.

Subjective and objective methods are commonly used to evaluate the load and physiological adaptations of athletes in training. However, there is a lack of data and their relationship concerning these tools in professional rowing training. This study aimed to investigate the relationship between the subjective and objective training loads of male rowers during a mesocycle. Field data were collected from 26 professional rowers over 6 consecutive weeks. Subjective training load variables (perceived exertion, acute: chronic workload ratio, training monotony and strain), and objective variables (white blood cell, red blood cell, blood urea, creatine kinase, testosterone, and cortisol) was collected, and correlations between various TL's were analyzed. All participants completed 6 weeks of training, which consisted of resistance (315 ± 88.5min/week), on-water (817.5 ± 9min/week), ergometer (341.9 ± 194.1min/week) and functional training (60min/week). Week 5 had the highest average weekly subjective training load (10849.23 ± 1361.14 AU), whereas Week 2 showed the highest training monotony (TM) with statistically significant differences compared to Week 1, week 3, week 5 and week 6 (p < 0.05), with small to moderate effect sizes (ES: 0.275-0.619). There were correlations among all the subjective training load variables. A positive correlation was found between sRPE_TL and TS (r = 0.80). Blood urea (BU) was positively correlated with weekly sRPE_TL (r = 0.44, p < 0.05), TM (r = 0.40, p < 0.05), TS (r = 0.43, p < 0.05) and ACWR (r = 0.44, p < 0.05). Similarly, creatine kinase (CK) was also associated with these indicators (r = 0.50-0.60). Testosterone and cortisol showed a consistently negative correlation (r = -0.64), but no relationship were found between these hormones and subjective training load. In conclusion, this study demonstrates a significant correlation between subjective and objective training loads in elite rowers. Our findings provide empirical evidence that ACWR, TM and TS serve as sensitive indicators of biochemical markers (CK and BU) fluctuations in professional rowing athletes. Given the correlation between the above objective and subjective indicators, coaches can adjust the training schedules based on the subjective data during training week, and combine with hematological tests to further promote positive adaptations.

Dynamic stretching (DS) is a conditioning technique commonly used in sports. However, its effects on contralateral joint flexibility and elastic properties of the targeted muscle over several weeks remain unclear. Similarly, its impact on muscle functions, such as force or power exertion, is poorly understood. This study aimed to examine the effects of a 12-week DS program targeting the ankle plantar flexors on the joint flexibility, muscle strength, and elastic properties of the plantar flexors in stretched and contralateral legs. Eighteen healthy young adults (12 males and six females, aged 18-24 years) participated in this study. DS was performed on one leg of the ankle plantar flexors for 12 weeks (3 days weekly), while the other leg served as a non-intervention. Dorsiflexion range of motion (DFROM), muscle stiffness, and ankle plantar flexion strength (rate of torque development and isokinetic muscle strength) were assessed before and after the intervention. The muscle stiffness was measured using shear wave elastography on the gastrocnemius. DFROM significantly increased in both conditions (p < 0.05), whereas gastrocnemius stiffness significantly decreased only in the DS condition (p < 0.05). No significant changes were observed in the non-intervention condition. The ankle plantar flexion rates of torque development and isokinetic strength did not change in either condition. These findings suggest that 12 weeks of DS can reduce muscle stiffness and improve joint flexibility without affecting muscle strength while enhancing contralateral joint flexibility without altering muscle stiffness or strength.

There is a great heterogeneity in the starting techniques used by international-level swimmers in relay events. The aim of the present study was to analyse and compare the two most commonly used relay start techniques by male and female competitive swimmers. Thirteen males and seven females national and international-level swimmers performed several 25-m trials with their preferred relay start (n = 91, short-step; n = 54, long-step technique). Linear mixed models examined the effects of gender and start technique, with 5-m start times as a covariate. Swimmers performing long-step showed faster 5-m (0.09 s, d = 1.10) and 10-m (0.09 s, d = 0.39) times than those performing short-step starts, regardless of gender (all p < 0.001). This was the result of i) longer block times, ii) faster horizontal velocities with lower peak forces during the leg step and iii) faster velocities with higher peak forces when driving-off the block in the long-step technique. In both relay techniques, females showed 0.11 s (d = 1.38) longer 5-m and 0.69 s (d = 2.99) longer 10-m (both p < 0.001) times compared to males with longer block times and slower velocities in all key events. Swimmers should take advantage of the new starting platforms to apply long-step start techniques that increase horizontal displacement but also forward velocity before leaving the block.

High-intensity resistance training is effective in improving muscle strength but poses a higher risk of atherosclerosis. Combining high-intensity resistance training with aerobic exercise can reduce atherosclerosis levels. Low-intensity resistance training combined with blood flow restriction does not require high-load force to stimulate muscles and may improve muscle strength and maintain arterial elasticity. The objective of the study was to investigate the effects of 12 weeks of low-intensity resistance training combined with blood flow restriction on body composition, muscle strength, and arterial elasticity in young people. The primary aim is to clarify whether the low-intensity resistance training combined with blood flow restriction training is a scientific training method to improve muscle strength and maintain arterial elasticity, and providing theoretical support for the scientific implementation of blood flow restriction training and the development of individualized training programs. Fifty-five college students were randomly divided into three groups: high-intensity resistance training, high-intensity resistance training combined with aerobic exercise, and low-intensity resistance training combined with blood flow restriction. Each group underwent 12 weeks of their respective training programs, and the effects on body composition, muscle strength, and arterial elasticity were examined. After 12 weeks, lean body mass significantly increased in both the high-intensity resistance training and low-intensity resistance training combined with blood flow restriction groups (P < 0.05). 1RM and knee isometric muscle strength significantly increased in all three groups (P < 0.05). Arterial elasticity significantly improved in both the high-intensity resistance training combined with aerobic exercise group and the low-intensity resistance training combined with blood flow restriction group (P < 0.05). Twelve weeks of high-intensity resistance training and low-intensity resistance training combined with blood flow restriction significantly improved body composition. All three training methods increased muscle strength. Low-intensity resistance training combined with blood flow restriction was more effective in improving arterial elasticity than high-intensity resistance training combined with aerobic exercise. Therefore, low-intensity resistance training combined with blood flow restriction is recommended as the preferred method to improve body composition, muscle strength, and arterial elasticity, reducing the risk of atherosclerosis.