International journal of sports physiology and performance最新文献

Purpose: Maximal muscle strength is often assessed with single-joint or repetition-maximum testing. The purpose of this study was to evaluate the reliability of countermovement-jump (CMJ) velocity-load testing and assess the relationship between CMJ velocity-load kinetics and concentric-isometric-eccentric multijoint leg-extension strength tested on a robotic servomotor leg press in trained athletes.

Methods: University athletes (N = 203; 52% female) completed 3 concentric, isometric, and eccentric maximum voluntary leg-extension contractions on the robotic leg press, followed by CMJ velocity-load testing with an additional external load of 0% (CMJBW), 30% (CMJ30), and 60% (CMJ60) of body mass. A linear model was fit for the CMJ takeoff velocity-load relationship to obtain the load intercept. Force-velocity parameters were obtained for the CMJ eccentric deceleration and concentric phases. Linear mixed-effects models were constructed to predict concentric, isometric, and eccentric leg-press force using the CMJ takeoff velocity-load relationship and CMJ kinetics.

Results: Isometric leg-press strength was predicted by load intercept and sex (P < .001, R2 = .565, prediction error = 14%). Concentric leg-press strength was predicted by load intercept, CMJ60 concentric impulse, and sex (P < .001, R2 = .657, prediction error = 10%). Eccentric leg-press strength was predicted by minimum downward velocity, CMJ60 eccentric deceleration impulse, and sex (P < .001, R2 = .359, prediction error = 14%).

Conclusions: Given the relevance of muscle-strength testing for sport performance and injury prevention, assessing force-velocity mechanics with loaded CMJ testing is a reliable and viable approach to predict maximal concentric, isometric, and eccentric leg-press strength in competitive athletes.

Purpose: The impact of weight cycling (WC)-successive weight loss (WL) and weight regain (WG)-on athlete performance is well documented, but effects on appetite are not. This study assessed the impact of a WC episode on dietary and appetitive profiles in athletes, considering sex and sport type.

Methods: Athletes (28 male, 20 female) from combat (n = 23), strength (n = 12), and endurance (n = 13) sports participated in 3 conditions during a WC episode (baseline, WL, WG). Measurements included body composition (dual-energy X-ray absorptiometry), energy intake (48-h food record), appetite (visual analog scale), dietary profile (questionnaires), and food reward (computer task).

Results: Overall, athletes lost 4.4% (2.3%) of their body weight and regained 4.5% (2.9%) (P < .001). Energy intake decreased during WL (P < .001) with a higher protein intake (% of energy intake) before returning to baseline in WG (P > .05). WL increased hunger, prospective food consumption, and desire to eat compared with the baseline condition, but these changes were not seen in WG. Liking and wanting for fat and sweet foods were higher during WL and remained elevated in WG (P < .05). No eating disorders were found during the WC episode, but combat-sport athletes and females had a higher binge-eating risk than others, independent of the condition.

Conclusions: Moderate WC episodes do not seem to impair appetite responses in athletes experienced with WC, likely due to their maintaining high physical activity levels. However, their long-term eating-behavior traits, especially in combat and female athletes, seem negatively affected. Practitioners should consider the long-term impacts of these WC practices on nutritional health.

Purpose: The aim of this study was to analyze the effects of bilateral and unilateral plyometric-training (PT) programs on jumping, sprinting, and change-of-direction (COD) ability in male postpubertal basketball players.

Methods: Forty-three young male basketball players (14.2 [1.2] y), from 4 squads belonging to an elite basketball club, were randomly assigned to 1 of 3 groups: (1) bilateral PT group (BG), (2) unilateral PT group (UG), and (3) control group (CG). The experimental groups followed a PT program twice weekly for 6 weeks, with BG and UG performing 2- and 1-legged jumps, respectively. Both groups completed the same number of vertical, horizontal, cyclic, and acyclic jumps. Pretraining and posttraining measurements included (1) countermovement jump (CMJ), (2) unilateral CMJ (CMJL and CMJR), (3) horizontal jump (HJ), (4) unilateral HJ (HJL and HJR), (5) straight-line sprint in 20 m (T20), and (6) V-Cut COD test (V-Cut).

Results: CMJ, CMJL, and CMJR were significantly improved by BG and UG (P < .001), while CG did not change. Both the BG and the UG improved their performance significantly (P < .01) in HJL and HJR, but only BG significantly increased (P < .05) HJ and showed significantly greater improvements than CG. Furthermore, only BG improved V-Cut performance (P = .03). Neither group increased T20. CG did not improve in any tests.

Conclusions: BG enhances single-leg and double-leg jump performance in vertical and horizontal directions, as well as COD ability. In contrast, an equivalent volume of unilateral PT only improves vertical jumps and unilateral HJs.

Purpose: To investigate technical regulation mechanisms of long-distance swimmers that differentiate optimal pacing strategies and the underlying kinematic parameters.

Methods: Twenty-one national and international swimmers were equipped with a sacrum-worn inertial measurement unit performed during 5000-m indoor French championships. Percentage of critical swimming speed (CSS), stroke rate, stroke length, jerk cost, stroke index, and mechanical proficiency score were computed by lap. Athletes were divided into groups of pacing effectiveness based on optimal potential performance level (OPPL)-optimal (nearOPPL) and suboptimal (farOPPL)-using functional clustering of percentage of the CSS. Race sections were analyzed with a change-in-slope detection method. Common stroke-regulation abilities and deviations by pacing groups were profiled by fitting hierarchical generalized additive models between mechanical variables and laps.

Results: The 2 clusters were discriminated by percentage of the CSS sustainment (P < .01). Optimal performers showed a +41.4% more stable pacing (2 race sections vs 3 for farOPPL) and a +36.7% higher end spurt, with a trend combining higher overall stroke rate (P = .08) with lower jerk cost (P = .17). Functional profiles showed that maintaining a higher stroke length and stroke index in a fatigued state, rather than overall values, allows the swinner to reach OPPL (P < .001). High regulation of mechanical proficiency score across the race, in line with pacing expectations of particular race sections, is a game changer to sustain CSS (P < .001).

Conclusions: Specific profiles of stroke regulations, regarding tradeoff between stroke smoothness and resultant speed, lead to optimal pacing during the 5000-m. The results of this study enhance the technical understanding of optimal pacing in long-distance pool races for coaches and swimmers.

Background: Practices to routinely monitor athletes are rapidly changing. With the concurrent exponential rise in wearable technologies and advanced data analysis, tracking training exposures and responses is widespread and more frequent in the athlete-coach decision-making process. Within this scenario, the concept of invisible monitoring emerged, which was initially vaguely defined as testing athletes without testing them. Despite sound practical applications and benefits (eg, reduced burden on player staff and more frequent measurement), a clear lack of constitutive definition has led to multiple cleavages in both research and practice, including ethical concerns.

Purpose: The purpose of this study is to (1) extend the current conceptualization of invisible monitoring by considering subdimensions of the concept and (2) its data-related and ethical challenges and (3) provide practical considerations to implement invisible monitoring. Monitoring burden (degree of obtrusion and frequency of measurement) and the number of constructs a single measurement tool can assess have been proposed as subdimensions of the concept of invisible monitoring. Challenges include the governance and analysis of data required to make estimates, validity and reliability of an invisible monitoring measure, and communication to athletes.

Conclusions: This commentary presents a first attempt to conceptualize invisible monitoring in the context of elite sport and provide subdimensions of the concept that can be used to classify choices of measurement tools. A consensus is required from both researchers and practitioners regarding its definition and operationalization to optimize current monitoring services to elite athletes.

Background: The Los Angeles 2028 Olympics will mark the debut of squash, a high-intensity sport characterized by repeated efforts, posing potential thermoregulatory challenges. The demanding nature of squash results in substantial metabolic heat production, with consequential heat strain exacerbated by the indoor environment of squash courts, where low to moderate evaporative potential limits effective cooling. Players often experience increased body-heat storage and thermal strain, with muscle cramps (an early warning sign of more severe heat-related illnesses) commonly observed during tournaments. Despite these challenges, there are limited data on the thermoregulatory responses of elite squash players during match play.

Purpose: We discuss the thermoregulatory challenges faced by squash players and highlight key areas for research. Additionally, practical guidelines are provided for practitioners preparing squash players for the Los Angeles 2028 Olympics.

Evidence: Preliminary findings from international squash tournaments reveal that elite players endure significant physiological strain, with core temperatures rising to 39.0 °C to 40.1 °C, despite matches being played in mild wet-bulb globe temperatures of 19.4 °C (0.9 °C). Sustained heart rates exceeding 90% of maximal heart rate further compound this thermal strain. However, research on how thermal strain affects squash-specific fitness, recovery, and stroke mechanics are lacking. Such information is crucial for evaluating the need and effectiveness of tailored mitigation strategies such as heat training/exposures and precooling and midcooling during warm-up and match play.

Conclusion: Systematic research into the thermal demands of squash and their impact on fitness and skills is needed. These insights can inform evidence-based strategies to safeguard athlete well-being and optimize performance at Los Angeles 2028.

Background: A recent advancement in velocity-based training involves estimating the maximum number of repetitions to failure (RTF) by analyzing the fastest velocity recorded within a set. A systematic review examining the fundamental characteristics of the RTF-velocity relationship is still lacking.

Purpose: This study aimed to (1) determine the basic properties of the RTF-velocity relationships (goodness of fit, reliability, and accuracy) and (2) offer guidance on implementing various methodological factors that can impact the RTF accuracy prediction.

Methods: Data were sourced from 3 databases: PubMed, SPORTDiscus, and Scopus. Studies were qualified for inclusion if they involved at least 2 sets performed to failure with different loads, utilized multijoint weight-lifting exercises, and monitored the RTF and fastest velocity for each set.

Results: Six studies demonstrated (1) robust goodness of fit, (2) acceptable to high between-sessions reliability for the velocities associated to each RTF (1-15 RTF), and (3) acceptable RTF prediction accuracy during fatigue-free sessions (long interset rest), but, when fatigued (ie, short interset rest) the accuracy was compromised except for athletes with high training experience (eg, >2 y training-to-failure experience).

Conclusions: The relationship properties remain unaffected regardless of the exercise (upper- vs lower-body), equipment (Smith- vs free-weight), velocity variable (mean and peak velocity), and resting time (from 5 to 10 min). However, the modeling procedure used (multiple- vs 2-point) did alter the accuracy. The individualized RTF-velocity relationships can be constructed through a linear regression model, but the failure experience seems to be a critical factor to increase its accuracy.

Purpose: Speed is a crucial physical characteristic where each lower-limb ankle plantar-flexor (PF) muscle needs to generate significant force; however, there is limited evidence about the relationship between single-limb isometric, and reactive strength forms, and linear sprint. The aim of this study was to determine the impact of the maximal unilateral isometric strength of the ankle PF muscle and reactive strength on sprint acceleration performance.

Material and methods: Thirty-two male floorball players (mean [SD] age 20.3 [3.0] y, height 181.5 [8.5] cm, body mass 77.4 [12.2] kg, and body mass index 22.3 [2.8]) from 2 clubs in the highest division in Latvia performed 20-m linear sprint, unilateral 10/5 repeated jump (reactive strength index [RSI]), ankle-dorsiflexion range of motion, and isometric seated plantar-flexion strength tests, where all data were used for correlational analysis.

Results: Unilateral RSI was associated with 20-m sprint time (r = -.52, P < .01) and average speed from 10 to 20 m (r = .72, P < .01). Relative PF strength was associated with unilateral RSI (r = .35, P < .05) and 20-m sprint time (r = -.36, P < .05), whereas ankle-dorsiflexion range of motion was associated with unilateral RSI jump height (r = .47, P < .05).

Conclusions: Floorball athletes with higher unilateral RSI and isometric PF muscle strength tend to accelerate faster, but subjects with better ankle-dorsiflexion range of motion jump higher in vertical repeated jumps. These findings suggest that both reactive and isometric strength are key indicators for sprint acceleration performance in floorball athletes, providing coaches with tools to monitor and improve performance.

Background: Mental fatigue (MF) is a psychobiological state that could negatively impact physical and cognitive performance, although the extent of this impact remains controversial. While laboratory studies have provided valuable insights into the acute effects of MF, their ecological validity in real-world sport settings remains limited. Recent research indicates that MF can naturally arise during sport activities, leading to chronic effects on endurance and perceptual-cognitive skills. These effects may persist beyond individual sessions, potentially increasing the risk of injury due to their cumulative nature.

Purpose: This commentary aims to guide future research by emphasizing the need to investigate the natural occurrence and chronic effects of MF in applied sport settings.

Conclusions: Understanding how MF develops and manifests in real-world settings, particularly individual differences in perception and response, is crucial for creating more effective management strategies. Addressing these factors will enable better support for athletes who may experience prolonged periods of MF that could affect their training and competitive performance. Future research should prioritize studying MF in natural sport settings to enhance the ecological validity of findings. By focusing on the chronic and cumulative nature of MF, as well as individual variability, researchers can develop more tailored and effective strategies for managing MF. This research will not only bridge the gap between laboratory studies and real-world applications but also contribute to more precise monitoring and intervention techniques. Ultimately, these advancements will improve athletes' ability to maintain peak performance and reduce the risk of injury, thereby enhancing overall athletic well-being.

Context: Agility is crucial for soccer players, and core training can improve it. One study showed significant agility improvements after an intervention including core training for athletes with groin pain. However, it is unclear if these improvements resulted specifically from the core exercises or the entire program. Additionally, the study lacked a control group, making the findings inconclusive.

Purpose: The current study aimed to explore the effect of core training, previously reported in the context of groin-pain rehabilitation, on agility performance in soccer players with groin pain.

Methods: Twenty soccer players with groin pain volunteered to participate. They were randomly assigned to a core training group (n = 10) and a control group (n = 10). Before and immediately after that period, agility performance (T test and Edgren Side Step Test) and self-reported outcomes (Copenhagen Hip and Groin Outcome Score) were assessed in both groups.

Results: No significant session × group interaction was observed in agility T test (F = 2.55; P = .12; ηp2=.12) and Edgren Side Step Test (F = 3.18; P = .09; ηp2=.15) performances. Besides, Copenhagen Hip and Groin Outcome scores showed significant improvements (P = .007 to <.001) in the core training group following the 12 weeks of core training and compared with the control group.

Conclusion: The results showed that soccer players with groin pain who received or did not receive core training showed similar agility performance. However, significant improvements in self-reported outcomes were observed in soccer players compared with the control group. Clinicians and coaches should therefore consider core training when designing training and rehabilitation programs for this population to enhance recovery.