International journal of exercise science最新文献

The aim of this study was to examine variations in countermovement jump (CMJ) performance after two velocity-based training (VBT) protocols in the half-squat exercise. Sixteen male beach volleyball athletes performed CMJ tests before and after three experimental sessions on the half-squat exercise. The two VBT protocols were performed in three sets, at a mean propulsive velocity (~ 0.49 m•s^-1) associated with relative intensity (~ 85% 1RM), with three minutes interset recovery. In the VL0-10 session, the participants stopped their sets upon reaching a velocity loss (VL) threshold of 10%. In the VL10-20 session, participants stopped their sets upon reaching a VL between 10% and 20%. The VL0-10 session showed progressive increases in CMJ height (P < 0.05). Comparisons between different times-points in each session showed that VL0-10 was greater than VL10-20 (mean difference = 3.7 cm; P < 0.001) after four minutes. Additionally, VL0-10 was greater than both VL10-20 (P = 0.005) and the control (P = 0.006) after six minutes. Thus, CMJ height performance appears to be optimised with VBT protocol involving small VL. For beach volleyball athletes, a half-squat protocol with 0-10% VL improves subsequent acute performance in CMJ height.

The purpose of this study was to assess the effect of a KN95 mask on the performance, physiological response, and perception of high-intensity interval training (HIIT). Twenty college-aged participants (Male: 10, Female: 10) completed a two-visit, crossover, counterbalanced study. The HIIT workout included four 1-minute "all-out" intervals at 3.5% of body mass with 4-minute rest intervals, performed with or without a KN95 mask. Following HIIT, participants remained on the cycle ergometer for a 15-minute recovery period. For each interval, peak power and average power were recorded. Throughout the HIIT workout and recovery, heart rate, blood lactate, muscle oxygenation, perceived exertion, and perceived recovery were measured. All data were assessed using trial×time ANOVAs with post hoc pairwise comparisons. Alpha level was set to p<0.05. All data are presented as mean±standard deviation. No significant interactions were noted for peak power (p=0.432), average power (p=0.674), blood lactate (p=0.533), perceived exertion (p=0.221), perceived recovery (p=0.333), or muscle oxygenation (p=0.991). A significant main effect of trial was noted for heart rate during recovery, with higher heart rate during the masked trial compared to control. A KN95 mask did not affect performance, physiological response, or perception during HIIT, though it led to elevated heart rate during recovery. These results suggest KN95 masks may not impair HIIT performance but can influence short-term post-exercise heart rate recovery.

This study compared performance on the Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) and the agility t-test between two playing surfaces, artificial turf and natural grass. This study also assessed agreement between estimated VO2max from the YYIR1 on artificial turf and natural grass with laboratory measured VO2max. Male collegiate soccer players completed three experimental sessions on separate days: YYIR1 and t-test on artificial turf, YYIR1 and t-test on natural grass, and a laboratory VO2max test. The validated Bangsbo et al. equation was used to estimate VO2max from YYIR1 distance. Participants covered more distance (2370 ± 662 vs. 1441 ± 463 m, p < .001) and reached higher maximal aerobic speed (17.29 ± 0.99 vs. 15.76 ± 0.78 km/h, p < .001) on natural grass. Agility t-test was faster on grass (8.75 ± 0.53 vs. 9.43 ± 0.73 s, p < .001). Grass estimated VO2max was higher than laboratory VO2max and turf estimated VO2max (58.0 ± 4.5 vs. 54.2 ± 3.4 vs. 49.8 ± 3.4 mL/kg/min, p < .001). Grass estimated VO2max was positively correlated with turf estimated VO2max (r = 0.91, p < .001). Bland-Altman analysis indicated that grass estimated VO2max overestimated laboratory VO2max and turf estimated VO2max underestimated laboratory VO2max (p < .001). Findings indicate playing surface is a critical factor in the performance outcome and accuracy of field-based aerobic fitness assessment. Findings emphasize the importance of considering environmental and contextual variables when administering and interpreting assessment data.

Strategic planning of research involves predicting the number of replications of the experiment needed to detect an expected effect. The power analysis to determine sample size for the proposed experiment requires known or estimated characteristics of existing distributions. When used well, power analysis reduces the risk of statistical errors, wasted efforts, and temptations to twist ensuing analyses to eke out a 'significant' result after data collections conclude. This editorial highlights some examples of how this process goes awry. Sections are dedicated to the role of researchers, the case for 'pilot' studies, and the critical involvement of reviewers as arbiters of best practices. Throughout, the importance of reporting standard statistical data to support conclusions is identified as the platform for enabling future power analyses. Logical, evidence-based pre-planning of studies and implementing standard statistical reporting increases transparency of research, the likelihood of a study to be cited in the future, and enhances the body of research that exercise scientists collectively build.

This research aimed to better understand the differences in health-related quality of life (HRQoL: general health, physical functioning), physical activity (PA), and health locus of control (HLOC: internal, external-chance, external-powerful others, God) among various ethnic groups. The study's sample included 185 individuals, 22 - 81 years of age, who were attending or employed by one of three religiously-affiliated higher education institutions during the 2020-2021 academic year. Participants voluntarily answered questions about their ethnic identity, HRQoL, PA level, and HLOC. To analyze the interaction of HRQoL, PA, and HLOC, a multiple regression analysis was conducted. Results showed the majority of respondents of all ethnicities had moderate to high levels of PA, which is opposite of CDC data. However, the scores for HLOC and HRQoL varied widely among ethnicities, with minority groups showing higher scores for external HLOC categories (chance, powerful others, God), as well as lower scores for both HRQoL categories (general health, physical functioning). Such differences call for better understanding of HLOC and HRQoL in different ethnic groups, which would allow for better tailoring of health education and promotion programming.

Prevalence studies with wearable devices are used to understand disparities in health-related physical activity behaviors and whether interventions are efficacious. However, studies have been limited to a binary definition of sex. This example analysis aimed to demonstrate how researchers can investigate differences in data beyond the sex-gender binary. Using a cross-sectional analysis of the All of Us Research Program dataset, participants' self-identified gender was categorized into Cisgender Female (n = 10,401), Additional Options (n = 27), Non-binary (n = 84), Transgender (n = 17), and Cisgender Male (n = 4,470). Fitbit data on active calories, steps, sedentary minutes, and very active minutes were analyzed following a valid statistical decision framework found in the companion editorial to this paper. Data were checked for normality using the Shapiro-Wilk test, and because data were not normally distributed, homogeneity was evaluated using the Brown-Forsyth test. The omnibus test for significant group differences was determined using the Kruskal-Wallis test, with significance accepted at p < 0.05. Effect sizes (ES) for omnibus test results were calculated using Epsilon squared. Results provide evidence for differences in physical activity metrics among gender groups (p < 0.001; active calories ES = 0.069, steps ES = 0.005, and very active minutes ES = 0.026). Cisgender males had higher active calories, steps, and very active minutes than cisgender females (40% more) and non-binary individuals (45% more). No differences were observed among other gender groups studied. These findings highlight that activity patterns vary beyond traditional binary classifications, emphasizing the need for gender-inclusive research in sport and exercise science. Specifically, the disparities observed underscore the importance of nuanced interpretations and tailored recommendations for diverse populations, addressing systemic gaps in supporting gender-diverse individuals in health and exercise behaviors.

It is well established that oral caffeine administration (3-9 mg/kg) is ergogenic, enhancing numerous aspects of physical performance including strength and power. However, the extent to which these effects translate to volleyball-specific skills remains unclear. The purpose of this study was to systematically review the effects of acute caffeine ingestion on performance outcomes in volleyball-specific actions. A systematic review of published studies was conducted using scientific databases from their inception through December 2024 (registered in PROSPERO, CRD420251006314). We included studies with blinded crossover experimental designs that compared caffeine ingestion to a placebo in samples of volleyball players performing physical performance tests or volleyball-specific tasks. The data from these studies were meta-analyzed to calculate standardized mean differences (Hedges' g) between placebo and caffeine conditions, using a random-effects model. The Q and I² statistic was calculated to verify the degree of similarity in the observed mean differences and the degree of heterogeneity, respectively. In total, after examining 60 effect sizes include 9 RCTs, 123 volleyball players with caffeine doses 1.7-6.4 mg/kg and administered 15-60 min pre-exercise, the meta-analysis indicated that caffeine improved performance in jumping activities (g = 0.24, p =0.009), strength-based tasks (g = 0.31, p =0.006) and performance in volleyball-specific skill tasks (g = 0.52, p =0.001). Specifically, subgroup analysis indicated significant improvement with caffeine in attack (g = 0.52, p =0.003), serve (g = 0.44, p =0.046) and accuracy (g = 0.68, p =0.001) tasks, but not in the velocity-based tasks (g = 0.26, p =0.168). Moreover, The I² statistics showed low heterogeneity for the studies (I² = 0 - 34.6). Acute caffeine ingestion appears to enhance physical performance in volleyball, with positive effects translating in jump and strength-based tests translated into improved skill execution during volleyball-specific tasks. Further research is needed to refine dosing strategies, account for individual differences based on habitual caffeine intake and player position, and assess long-term outcomes of caffeine intake.

High-incline walking is a popular mode of exercise and often serves as an alternative to level-grade running for improving cardiovascular fitness. This study examined the muscle activation and biomechanical differences between high-incline walking (HIW) at a 20% grade and level-grade jogging (LGJ) at matched exercise intensities. Nineteen physically inactive adults (18-31 years) participated. Participants completed two isocaloric exercise trials (HIW and LGJ), each lasting ten minutes. EMG data were obtained from eight muscles: biceps femoris (BF), gluteus maximus (GM), lateral gastrocnemius (LG), tibialis anterior (TA), vastus lateralis (VL), anterior deltoid (AD), erector spinae (ES), and soleus (SOL). Resultant accelerations on the foot and sacrum were measured using inertial measurement units (IMUs). At matched isocaloric intensities between LGJ and HIW, mean peak resultant acceleration was significantly higher in LGJ for the foot (22.14 ± 8.44 m/s²) and sacrum (27.21 ± 7.92 m/s²). Peak EMG activation was significantly greater during LGJ in TA (40.9% ± 21.4) and VL (52.6% ± 39.8). The EMG integral was significantly greater in the LGJ for the TA (13.8% ± 5.0) than during HIW. Despite being matched isocalorically, LGJ increased peak and integral muscle activation and produced higher foot and sacrum accelerations. These findings highlight HIW as a lower-impact, yet equally demanding, alternative to LGJ, with implications for exercise prescription and injury prevention.

Isometric handgrip (IHG) coupled with post-exercise muscular ischemia (PEMI) and the cold pressor test (CPT) have been demonstrated to increase measures of hemodynamics and to reduce vagal tone. However, little is known about how acute resistance exercise (RE) alters these responses. The purpose was to evaluate an acute bout of RE in conjunction with a single- or dual-stressor task on hemodynamics and autonomic modulation in resistance-trained individuals. Ten resistance-trained individuals (Mean ± SD; Age: 23 ± 3 years) completed a single-(SS: IHG + PEMI only) or dual-stressor (DS: IHG + PEMI + CPT) task condition. Before and after the acute RE variables were monitored during five minutes of rest (REST), two minutes of IHG, three minutes of PEMI with or without concurrent CPT (STRESS). Hemodynamics included heart rate (HR), mean arterial pressure (MAP), cardiac output (Q,). stroke volume (SV) and total peripheral resistance (TPR), while autonomic data were measured via heart rate variability and heart rate complexity. There were no significant (p > 0.05) three-way interactions for HR, Q, or TPR. However, there was a significant three-way interaction (p = 0.007) for SV such that SV was significantly increased during STRESS compared to REST in the SS condition but did not change in the DS condition. There were no significant (p > 0.05) interactions for measures of autonomic modulation. These data suggest that young, resistance-trained individuals have a significant cardiac sympathetic reserve and thus a large capacity to handle multiple stressors following acute RE.

We investigated the effects of a new approach with mixed session periodization resistance training (MSP) on functional performance, muscular strength, and body composition in older women. Twenty-one participants were tested before and after the intervention (10 weeks) and were allocated for convenience into two groups according to their available time; our schedule made two classes available, one at 6 a.m. (MSP), and one at 7 a.m. (active group-control). Results were analyzed through a mixed-model analysis with repeated measures. There was a group vs. time interaction for timed up and go (p < 0.001, η_p ² = 0.478; MSP: pre = 8.2 ± 1.3s, post = 7.1 ± 1.1 s; CON: pre = 7.8 ± 1.2s, post = 7.6 ± 1.1 s), stair ascent (p = 0.001, η_p ² = 0.478; MSP: pre = 12.5 ± 2.1s, post = 10.8 ± 1.9s; CON: pre = 12.3 ± 2.0s, post = 12.1 ± 1.8s), and stair descent tests (p < 0.001, η_p ² = 0.579; MSP: pre = 13.2 ± 2.3s, post = 11.4 ± 2.0s; CON: pre = 12.9 ± 2.2s, post = 12.7 ± 2.1s). There was also a group vs. time interaction for concentric knee extension (p = 0.001, η_p ² = 0.465; MSP: pre = 120.5 ± 18.7 Nm, post = 135.6 ± 20.1 Nm; CON: pre = 118.3 ± 17.9 Nm, post = 119.8 ± 18.2 Nm), and for bench press (p < 0.001, η_p ² = 0.635; MSP: pre = 25.3 ± 4.5 kg, post = 30.1 ± 5.0 kg; CON: pre = 24.8 ± 4.3 kg, post = 25.2 ± 4.4 kg), lat pulldown (p = 0.005, η_p ² = 0.345; MSP: pre = 30.2 ± 5.1 kg, post = 35.0 ± 5.6 kg; CON: pre = 29.8 ± 5.0 kg, post = 30.1 ± 5.1 kg), deadlift (p < 0.001, η_p ² = 0.606; MSP: pre = 45.6 ± 7.2 kg, post = 52.3 ± 7.8 kg; CON: pre = 44.9 ± 7.0 kg, post = 45.3 ± 7.1 kg), and squat (p < 0.001, η_p ² = 0.694; MSP: pre = 40.5 ± 6.8 kg, post = 47.2 ± 7.5 kg; CON: pre = 39.8 ± 6.7 kg, post = 40.1 ± 6.8 kg). There were no significant changes in body fat percentage, absolute body fat, or lean mass. Our findings demonstrated that independently of sequence, the mixed session periodization model resulted in increased muscle strength and functional capacity in aging adults, but no significant changes in body composition were observed.