International journal of sports physiology and performance最新文献

Purpose: To characterize the time structure of K1 kickboxing matches of Glory World Series (Glory) and to determine potential differences between winners and losers.

Methods: Seventeen matches of Glory 2019 (17 first rounds, 13 second rounds, and 8 third rounds) were video-analyzed to quantify (1) the time expended in high- and low-intensity activity and pauses, (2) the number and pattern of attacks, and (3) the number of effective attacks. Fighters were professional male athletes (age 27.9 [2.7] y) of the middle-weight category (85 kg). The number and the pattern of attacks and the number of effective attacks were compared between winners and losers.

Results: The mean times expended in high- and low-intensity activity and pauses were 234.6 (133.9) seconds, 97.4 (60.1) seconds, and 36.0 (19.9) seconds, respectively, resulting in an effort-to-pause ratio of ∼1.8:1. Compared with losers, winners presented (1) a greater number of attacks in the second round (P = .004) and entire match (P = .009), (2) a greater number of attacks containing 3 attacks in sequence in the second round (P = .001) and attacks containing >3 attacks in the third round (P = .049), and (3) a greater number of effective attacks in the second round (P = .011) and entire match (P = .008).

Conclusions: The findings of the present study indicate that K1 kickboxing in Glory matches presents a ∼1.8:1 effort-to-pause ratio and that winners perform more attacks, effective attacks, and attacks in sequence. These data provide useful insights to improve the training specificity of kickboxing athletes.

Purpose: To assess the effect of whole-body cryotherapy (WBC) on postmatch recovery in basketball.

Methods: Using a crossover design, 17 youth male players (age 16.2 [1.2] y, stature 190.5 [9.4] cm, body mass 79.2 [9.6] kg, experience 9.9 [3.9] y) completed 2 simulated matches, followed by WBC (4 min, -75 to - 85 °C) or a placebo intervention (CON). Countermovement-jump height, change-of-direction performance, 10- and 20-m sprint times, heart-rate variability (log-transformed squared root of the mean sum of the squared differences between R-R intervals [Ln-rMSSD]), muscle soreness, and perceived recovery (Perceived Recovery Status Scale [PRS]) were recorded at prematch, postmatch, postrecovery, and 24 hours postmatch. Additionally, Ln-rMSSD was recorded upon awakening on match day and the following morning.

Results: Compared with CON, higher PRS values were reported in WBC at prematch and postrecovery (P ≤ .026), while no significant between-interventions differences were found for any other measure (P > .05). Regarding the effect of time, our findings revealed that 20-m sprint times, Ln-rMSSD, and PRS deteriorated in both interventions from prematch to postmatch (ie, acute changes, P ≤ .045), while muscle soreness worsened in WBC only (P ≤ .003). Conversely, countermovement-jump height, change-of-direction, and 10-m sprint performance were unaffected by match play in the acute phase (P > .05), while none of the investigated measures showed impairments at 24 hours postmatch, compared with prematch (P > .05).

Conclusions: Overall, these findings suggest that WBC was mostly ineffective for improving postexercise recovery in the investigated sample, with benefits observed for perceived recovery being potentially influenced by the participants' status at baseline (ie, higher prematch PRS scores in WBC compared with CON).

Purpose: To investigate the effects of transcranial direct-current stimulation (tDCS) applied over the primary motor cortex (M1) and cerebellum on balance control and shooting accuracy in elite ice hockey players.

Methods: Twenty-one elite ice hockey players underwent anodal tDCS over the M1 (a-tDCSM1), anodal tDCS over the cerebellum (a-tDCSCB), concurrent dual-site anodal tDCS over the M1 and the cerebellum (a-tDCSM1+CB), and sham stimulation (tDCSSHAM). Before and after receiving tDCS (2 mA for 15 min), participants completed an ice hockey shooting-accuracy test, Pro-Kin balance test (includes stance test and proprioceptive assessment), and Y-balance test in randomized order.

Results: For static balance performance, the ellipse area in the 2-legged stance with eyes open and the 1-legged stance with the dominant leg significantly improved following a-tDCSM1, a-tDCSCB, and concurrent dual-site a-tDCSM1+CB, compared with tDCSSHAM (all P < .05, Cohen d = 0.64-1.06). In dynamic balance performance, the average trace error of the proprioceptive assessment and the composite score of the Y-balance test with the dominant leg significantly improved following a-tDCSM1 and concurrent dual-site a-tDCSM1+CB (all P < .05, Cohen d = 0.77-1.00). For the ice hockey shooting-accuracy test, shooting-accuracy while standing on the unstable platform significantly increased following a-tDCSM1 (P = .010, Cohen d = 0.81) and a-tDCSCB (P = .010, Cohen d = 0.92) compared with tDCSSHAM.

Conclusion: tDCS could potentially be a valuable tool in enhancing static and dynamic balance and shooting accuracy on unstable platforms in elite ice hockey players.

Purpose: This study both investigated and compared Gaelic games players' and practitioners' perceptions of the importance of postexercise recovery strategies.

Methods: Gaelic players (n = 1178 [n = 574 female], age 24.6 [6.6] y) and practitioners (n = 148 [n = 29 female], age 35.9 [8.7] y) completed a questionnaire assessing their perceptions of various postexercise recovery strategies (importance ranked out of 5 [1 "not important at all" to 5 "extremely important"]). Players were further categorized by playing standard into developmental (club/collegiate; n = 869) and national (intercounty; n = 309) levels and by sport: Gaelic football (n = 813), camogie/hurling (n = 342), and Gaelic handball (n = 23). Practitioners were categorized as sport coaches (n = 67), strength and conditioning staff (n = 34), nutrition staff (n = 15), and athletic rehabilitation staff (n = 32).

Results: Gaelic players prevalently perceived sleep (76.4%), rehydration (72.5%), postexercise meal (48.4%), stretching (47.6%), active cool-down (25.1%), foam rolling (23.1%), and massage by therapist (22.6%) as "extremely important." Practitioners prevalently perceived sleep (90.1%), rehydration (83.6%), postexercise meal (76.6%), daytime naps (36.2%), stretching (25.4%), discussion with teammates (24.6%), and getting into nature (19.4%) as "extremely important."

Conclusions: While strategies with well-documented efficacy such as sleep, nutrition, and rehydration were rated as most important, a distinct and possibly problematic disconnect exists between the perceived importance of many strategies and their empirically demonstrated effectiveness. For instance, active cool-downs and stretching were perceived as highly important despite prevailing evidence suggesting that their effects are often small in magnitude. Collectively, work promoting optimal recovery practices and aligning player-practitioner perspectives would be beneficial to maximize time and resource allocation and enhance player buy-in.

Purpose: Agility in young soccer players has long been associated with physical attributes like strength, speed, and power. The aims of this study were to investigate the relationship between cognitive factors and agility performance in this unique population.

Methods: 39 young soccer players age 13.56 (SD 0.58) years were assessed for leg-muscle function (jump tests) and maturation status (peak height velocity). The Y-Agility Test, which included decision making in players, was used to measure performance. Cognitive factors such as perceptual skills and decision making were evaluated with the Y-Agility Test.

Results: The linear regression showed an absence of significance between the Y-Agility Test and drop-jump contact (P = .283), Y-Agility Test and drop-jump flight (P = .185), Y-Agility Test and squat jump (P = .868), and Y-Agility Test and countermovement jump (P = .310). The linear mixed-model analyses suggested a difference between early-average maturers (P = .009) and early-late maturers (P = .005) but did not show a difference between average-late subjects (P = 1.000). Drop-jump flight did not show a difference in maturation (early-average P = 1.000; early-late P = 1.000; average P = 1.000). Squat-jump performance did not demonstrate any significance (early-average P = .618; early-late P = 1.000; P = 1.000). Countermovement-jump performance did not show any significance (early-average P = 1.000; early-late P = 1.000; average-late P = .492). Finally, agility performance does not show any significance between maturation levels (early-average maturer P = .450; early-late P = 1.000; average-late P = .830).

Conclusion: Agility in young soccer players appears to follow a nonlinear trajectory, with cognitive factors possibly playing a more significant role than previously thought.

Purpose: The objective of this study was to investigate the effects of morning versus evening plyometric training (PT) on performance adaptations in male volleyball players.

Methods: A total of 30 collegiate national-level young male volleyball players (age = 21.9 [2.1]; height = 186 [4.1]; body mass = 82.4 [4.6]) were randomly divided into 3 groups: morning PT (MPT), evening PT (EPT), and an active control group, each group consisting of 10 subjects. The players engaged in PT sessions twice weekly for a period of 6 weeks. The evaluation of biomotor abilities such as countermovement vertical jump, standing long jump, spike jump, block jump, 10-m sprint, T-test, sit and reach, and Y-balance test took place in the morning and evening before and after the intervention.

Results: Both the MPT and EPT groups indicated significant (P < .05) improvements in all biomotor abilities from pretraining to posttraining during both the morning and evening testing sessions. Furthermore, the MPT group displayed greater adaptive responses in the vertical jump (P = .001), standing long jump (P = .023), and Y-balance test (P ≤ .01) compared to the EPT group. Time-of-day fluctuations were the same between the MPT and EPT groups at the pretest. Conversely, EPT demonstrated significantly more daytime variations than MPT in the jump, sprint, and balance tests at postintervention (P < .05).

Conclusion: Engaging in PT at specific times of the day has a significant impact on biomotor ability adaptations, with a focus on morning being more favorable than the evening for achieving greater gains in jump and balance performance of volleyball players.

Purpose: Maximal speed is an important physical-fitness attribute for female Australian footballers. The effects of sprint training, maximal strength, and technical training have been reported in laboratory studies. However, no study has determined the combined effect and relative contribution of these training modalities on maximal speed adaptation in situ. Therefore, the aim of this study was to determine the training factors affecting maximal speed adaptation during a preseason in subelite female Australian Rules footballers.

Methods: Maximal speed during field training, predicted 1-repetition maximum (1RM) for box squat and hip thrust, and sprint biomechanics were assessed during early and late preseason (∼9 wk apart) in 15 female subelite Australian Rules Football players (age 20 [3] y). On-field training volume and intensity (total distance, high-speed running, very-high-speed running, and maximal speed) were determined using a Global Positioning System. A multivariate regression model was used to determine the factors associated with changes in maximal speed across the preseason.

Results: The preseason training program had a small effect on maximal speed and large to very large effects on strength and sprint biomechanics. The multivariate regression with the greatest fit (P < .001, R2 = .939) included change in estimated 1RM box squat (β = -0.63), total distance per week (β = -0.55), and change in hip projection (β = 0.16) as factors. Multivariate regression of biomechanical factors (P = .044, R2 = .717) and maximal strength factors (P = .003, R2 = .676) were also significant.

Conclusion: The development of maximal speed across a preseason is dependent on (1) total distance per week, (2) maximal strength adaptation, and (3) sprint technique adaptation in female subelite Australian rules football players.

Purpose: To compare the effects of 6-week barbell weighted-jump-squat (WJS) training with and without eccentric load reduction on explosive performance.

Methods: Twenty well-trained male athletes were randomly assigned to either an experimental group (n = 10) or a control group (n = 10). Participants completed 12 WJS training sessions (6 sets of 5 repetitions of barbell back squat at 30% of 1-repetition maximum [1RM]) twice a week over a 6-week period. While the control group used 0% eccentric loading (ie, traditional WJS), the experimental group utilized a 50% eccentric loading reduction with a mechanical braking unit (ie, eccentric load set at 15% of 1RM). Performance assessments, including countermovement jump, 20-m sprint, standing long jump, and 1RM barbell back squat, were conducted both before (pretests) and after (posttests) the intervention.

Results: Both the experimental group and the control group demonstrated a significant increase in countermovement-jump height (+6.4% [4.0%] vs +4.9% [5.7%]; P < .001) and peak power output (+2.3% [2.7%] vs +1.9% [5.1%]; P = .017), faster 20-m sprint times (+9.4% [4.8%] vs +9.2% [5.5%]; P < .001), longer standing long jump (+3.1% [2.5%] vs +3.0% [3.3%]; P < .001), and higher 1RM back squat (+6.4% [4.0%] vs +4.9% [5.7%]; P < .001) from pretests to posttests. However, there was no significant condition × time interaction for any variable (all P ≥ .294).

Conclusions: Both WJS training methods, with and without load reduction in the eccentric phase, effectively enhance explosive performance. Nevertheless, athletes in later stages of injury rehabilitation or intense training may find reducing eccentric load a more tolerable strategy for achieving similar performance gains compared with traditional isoinertial loading.

Background: The benefits of oral caffeine intake to enhance several aspects of physical performance, such as aerobic endurance, strength, power, and muscle endurance performance, are well supported. However, how the physical performance benefits of caffeine supplementation are translated into better specific actions in intermittent sports during real or simulated competition has been the topic of fewer investigations, and their results need to be appropriately reviewed and meta-analyzed.

Objective: The aim of the study was to investigate the effects of acute caffeine intake on specific actions in intermittent sports involving decision making and high-intensity efforts (eg, team, racket, and combat sports) during real or simulated competitions.

Methods: All studies included had blinded and crossover experimental designs, and we conducted a risk-of-bias analysis. In total, we included 24 studies. A meta-analysis was performed using the random-effects model to calculate the standardized mean difference (SMD) estimated by Hedges g and 95% CIs.

Results: Caffeine ingestion increased high-intensity sport-specific actions during competition, such as the number of sprints (SMD: 0.48; 95% CI, 0.23-0.74), body impacts (SMD: 0.28; 95% CI, 0.08-0.49), accelerations (SMD: 0.35; 95% CI, 0.06-0.63), decelerations (SMD: 0.63; 95% CI, 0.12-1.14), and high-intensity offensive efforts (SMD: 0.36; 95% CI, 0.11-0.61). Additionally, caffeine ingestion induced a higher positive or success rate of actions during real or simulated competition (SMD: 0.44; 95% CI, 0.19-0.69).

Conclusion: The current meta-analysis provides evidence of caffeine supplementation in increasing high-intensity efforts and the success rate of sport-specific actions during real or simulated competition.

Purpose: This study explored the effects of 4 bench-press (BP) training programs with different velocity-loss (VL) thresholds (0%, 15%, 25%, and 50%) on strength gains and neuromuscular adaptations.

Methods: Forty-six resistance-trained men (22.8 [4.4] y) were randomly assigned into 4 groups that differed in the VL allowed within the set: 0% (VL0), 15% (VL15), 25% (VL25), and 50% (VL50). Training loads (40%-55% 1-repetition maximum), frequency (2 sessions/wk), number of sets (3), and interset recovery (4 min) were identical for all groups. Participants completed the following tests before and after an 8-week (16-session) BP training program: (1) maximal isometric test, (2) progressive loading test, and (3) fatigue test in the BP exercise. During all tests, triceps brachii muscle electromyography was assessed.

Results: After completing the resistance-training program, no significant group × time interactions were noticed for isometric and dynamic BP strength variables. The dose-response relationship exhibited an inverted U-shaped relationship pattern, with VL25 showing the greatest effect sizes for almost all strength variables analyzed. The total number of repetitions performed during the training program increased as the VL magnitude increased.

Conclusions: The group that trained with high VL threshold (50%), which performed a total of 876 repetitions, did not experience additional strength gains compared with those experienced by the 0%, 15%, and 25% of VL groups, which performed significantly fewer repetitions (48, 357, and 547, respectively). These findings suggest that when light loads (40%-55% 1-repetition maximum) are used, low and moderate VL thresholds (0%-25%) provide a higher training efficiency.