International journal of sports physiology and performance最新文献

Purpose: Lifting straps (LS) are popular tools used by resistance-training (RT) practitioners with the intention of improving exercise performance. This tool is worn around the wrist to enhance grip on the barbell or other RT equipment and potentially decrease grip limitation throughout the exercise-a limitation that is usually reported by practitioners, especially during deadlifts, weightlifting movements, and pulling exercises. However, this knowledge remains mostly based on common experiential beliefs. Thus, this narrative review aims to highlight the current knowledge on the impact of LS in RT, focusing on physiological and biomechanical effects, exercise performance, chronic training adaptations, and safety concerns, and also to expose the existing literature gaps and distinguish between evidence-based findings and empirical assumptions.

Conclusion: Evidence suggests that LS can enhance maximal strength and grip perception. However, for pulling/back exercises, no consistent effects have been observed. In addition, LS may increase mechanical work in the deadlift, but contrary to common belief, they appear not to contribute to increased muscle recruitment. Furthermore, no scientific evidence supports the chronic effects of LS usage in training; it is still a hypothesis. Finally, this review offers future research insights to assist sport scientists in designing and conducting more comprehensive investigations on this topic, ultimately enhancing the understanding and application of LS in RT.

Purpose: To assess total, weekly, and session rating of perceived exertion (sRPE) training load (TL), identify factors influencing sRPE-TL, and analyze interplayer, individual relative-to-team, and intraplayer variability in elite youth female footballers.

Methods: All outfield players (age 13.7 [0.5] y) from the U14 (under 14 y of age) team of a Spanish Women's First Division academy were monitored over a 19-week competitive period. Players reported sRPE after each training session and match. TL was calculated as sRPE × session duration. Individual- and team-level analyses were performed.

Results: Players completed 95% (4%) of sessions. Total and weekly team sRPE-TL averaged 19,717 (1708) and 1200 (104) AU (arbitrary units), respectively. Playing position had no significant effect (P > .05), whereas training day significantly influenced session TL (P < .001), with matches showing substantially lower TL than training sessions (Cohen d: 2.85-4.34). Interplayer variability was small to moderate (coefficient of variation 7%-14%). Differences between individual and team means ranged from -26% to +25%, trivial to very large. Intraplayer variability was moderate to very large (coefficient of variation 10%-53%), with session-level variability classified as very large for all players. The interaction between individual-team difference and intraplayer variability was analyzed.

Conclusions: Despite consistent team-level TL, marked individual differences emerged. Two individual TL profiles were identified: (1) mean-aligned versus mean-divergent and (2) stable versus unstable. Combining both dimensions enhances individual TL profiling and supports tailored training strategies. These findings emphasize the need to move beyond team averages to ensure appropriate monitoring and individualized development in elite youth female football.

Purpose: Although previous studies have compared strength-training adaptations between free weights (FW) and machine-guided exercises, those studies did not use a Smith machine (SM), which most closely replicates the exercises performed with FW. Thus, the aim of the present study was to investigate the chronic effects of strength-focused, velocity-based training regimens using FW versus SM.

Methods: Thirty-seven sport-science students (14 female) were assigned, balanced by sex and relative strength, to either an FW or SM training group. The training program lasted 8 weeks (2 sessions/wk), and participants performed 4 sets per exercise (back squat and bench press) at 70% of their 1-repetition maximum with moderate effort levels (20%-25% velocity loss). Load-velocity profile parameters (load-axis intercept, velocity-axis intercept, and area under the load-velocity relationship line), cross-sectional areas of the vastus lateralis and pectoralis major muscles, and the number of repetitions to failure in the bench-press exercise were assessed before and after the training program. Mechanical variables were assessed using both FW and SM.

Results: All variables, with the exception of back-squat velocity-axis intercept (P = .124), improved in both training groups. The changes in load-axis intercept and area under the load-velocity relationship line were more pronounced when the training and testing conditions matched. Failure in the bench-press exercise and cross-sectional areas of the vastus lateralis and pectoralis major showed comparable improvements for both training groups, while velocity-axis intercept tended to improve more in the SM group.

Conclusions: The general population, unconcerned with the specificity of strength adaptations, can choose a training modality (FW or SM) based on personal preferences.

Purpose: The purpose of this research was to report isometric hip adduction and abduction strength reference values of men's and women's Gaelic football and rugby union players and compare values between sexes and between sports.

Methods: This cross-sectional cohort study consisted of 331 club-level athletes. Maximum isometric hip adduction squeeze and abduction press strength values were measured with a ForceFrame across several testing positions.

Results: Hip adduction squeeze and abduction press strength reference values for men's and women's Gaelic and rugby union footballers were provided with mean and 1 SD. A 2-way analysis of variance demonstrated significant sport × sex interaction main effects for hip adduction squeeze (η2 = .159-.228), abduction press (η2 = .099-.144), and adduction:abduction ratio (η2 = .120). Men demonstrated significantly greater relative (Newtons per kilogram) maximum isometric hip adduction squeeze (15.5%-26.4%, 0.48-1.00 N/kg) and hip abduction press (9.6%-19.6%, 0.20-0.67 N/kg) strength across all testing positions when compared with women of the same sport. Male Gaelic football players demonstrated significantly greater hip adduction (8.7%-14.0%, 0.30-0.52 N/kg) and abduction (6.1%-8.6%, 0.16-0.31 N/kg) strength (Newtons per kilogram) than their rugby counterparts, while no significant between-sports differences in strength were observed between female athletes.

Conclusion: Reference values are provided with mean and 1 SD. Sport and sex interaction had significant main effects for hip adduction, abduction, and adduction:abduction ratio, with medium to large effect sizes. Male athletes demonstrate significantly greater hip strength than female athletes of the same sport, and male Gaelic players demonstrate greater hip strength than male rugby players.

Purpose: The recently announced Enhanced Games (EG) positions itself as a revolutionary alternative to the Olympic Games, proposing a sporting event in which performance-enhancing drugs are not only permitted but medically supervised and celebrated. Founded by Dr Aron D'Souza, the initiative markets itself as a more transparent, scientific, and technologically progressive and equitable model of elite sport. In contrast to the World Anti-Doping Agency's long-standing global commitment to banning doping substances, the EG advocates for full transparency and deregulation of enhancement practices, aiming to eliminate what is perceived as hypocrisy in contemporary elite athletics. The purpose of the current commentary is to critically evaluate the medical, societal, ethical, and regulatory consequences of the EG. Conclusions: We argue that many of the claims made by the advocates of the EG are flawed and the use of scientific rhetoric is often misleading. Moreover, we argue that the EG represents a high-risk social experiment with potentially profound medical, societal, and ethical consequences that abandons the principles that govern current elite sports: respect for athlete autonomy and health, fair competition, and the quest for sporting and human excellence. We point to the need for a renewed commitment to these principles, not their abandonment. Contrary to the EG, strengthening antidoping systems and investing in safe, evidence-based performance support are all viable paths forward. The EG may produce new records but challenge radically the moral relevance and nature of sport.

Purpose: This study aimed to explore the use of predictive and prescriptive machine-learning models for managing training loads in professional soccer, with a focus on the rating of perceived exertion (RPE). Using data from a Belgian Pro League club, we evaluated the effectiveness of these models in predicting and prescribing optimal training regimens.

Methods: Data from 14 players across a full competitive season were analyzed. Predictive models including linear regression, random forest, and XGBoost were compared using the root-mean-square error and the mean absolute error. SHapley Additive exPlanations values were used to interpret feature importance. A prescriptive model based on the counterfactual recurrent network was developed to optimize training inputs for desired outcomes.

Results: The XGBoost model demonstrated the best predictive performance (root-mean-square error: 1.262), with session distance identified as the most significant driver of RPE. While the prescriptive counterfactual recurrent network model showed slightly lower predictive accuracy (root-mean-square error: 1.379), its unique advantage lies in estimating counterfactual outcomes, allowing for the simulation of future RPE trajectories under different potential training plans and providing actionable insights for personalized training prescription.

Conclusions: Predictive modeling effectively estimates RPE, and prescriptive modeling offers the added benefit of optimizing training strategies. The integration of these approaches supports data-driven decisions in professional soccer, enhancing player performance and recovery. Future research should expand sample sizes and validate these methods across diverse sports and contexts.

Purpose: This study aimed to (1) compare sprint- and jump-performance outcomes 6 hours following sprint-priming stimuli involving different external loads and (2) investigate whether maximal dynamic strength level influences sprint-priming outcomes.

Methods: Sixteen recreationally active males completed 5 sprint-priming activities (control [no physical activity] and 0%, 10%, 20%, and 30% body mass) in randomized order. Twenty-meter-sprint, countermovement-jump, and squat-jump tests assessed performance outcomes.

Results: Faster 0- to 20-m sprint times were observed following 0% (mean difference [MD] = -0.124 s; 95% CI, -0.184 to -0.064; P < .001), 30% (MD = -0.099 s; 95% CI, -0.160 to -0.039; P = .002), 10% (MD = -0.072 s; 95% CI, -0.132 to -0.012; P = .020), and 20% (MD = -0.070 s; 95% CI, -0.130 to -0.010; P = .024) sprint- priming stimuli compared with control. The 0% sprint-priming stimulus (MD = -0.068, -0.053 s; 95% CI, -0.115 to -0.008; P = .005-.024) elicited faster 0- to 5- and 0- to 10-m sprint times than 10%, 20%, and control. Faster 0- to 10-m sprint times were also observed following the 0% sprint-priming stimulus (MD = -0.096, -0.053 s; 95% CI, -0.153 to 0.000; P = .001-.049) compared with 10%, 20%, and control conditions. Additionally, the 30% sprint-priming stimulus (MD = -0.059 s; 95% CI, -0.115 to -0.002; P = .043) elicited significantly faster 0- to 10-m sprint times than control. Jump measures were unaffected. Maximal dynamic strength was not associated with sprint-performance outcomes.

Conclusion: Sprint priming may enhance performance in tasks requiring maximal acceleration over 20 m when assessed 6 hours later.

Purpose: This study aimed to (1) evaluate the acute metabolic, mechanical, and perceptual responses to curve versus linear repeated-sprint-training (RST) protocols in highly trained youth soccer players and (2) analyze whether the sprint trajectory influences the time course of recovery following RST protocols.

Methods: Twenty-seven highly trained youth soccer players randomly performed 2 RST protocols (12 × 17 m with 15-s intervals) with different trajectories: linear or curve (radius of 9.15 m). Blood lactate concentration, countermovement-jump height, modified reactive strength index, and myotonometric measurements of the biceps femoris long head (stiffness, frequency, and decrement) were assessed before and 0 minutes, 5 minutes, and 24 hours after the protocols. Likewise, best and average sprint velocities were recorded in both protocols, and perceptual responses were evaluated using Borg and Hooper scales.

Results: Linear RST showed higher velocity outputs than curve RST (P < .001). No significant time × condition interactions were observed for blood lactate concentration, countermovement-jump height, modified reactive strength index, time to takeoff, or myotonometric measurements (all P < .05), except for right-leg stiffness (P = .047), which significantly increased from 0 minutes to 24 hours only after curve RST (P < .05). Additionally, players also reported poorer sleep quality (P = .045) following the curve RST.

Conclusions: Overall, these findings suggest that the acute metabolic, mechanical, and perceptual demands of RST are not trajectory dependent. Therefore, strength and conditioning coaches can use both trajectories to address soccer-specific sprint demands in elite youth soccer players.