International journal of exercise science最新文献

The purpose of this study was to observe the changes in body composition of collegiate marching band artists after a competitive season NCAA Division I football season. Thirty-seven marching artists (7 females, 31 males; age: 21.5 (1.4) years; height: 177.2 (9.5) cm had body fat percentage (BF%), fat mass (FM), android adiposity, gynoid adiposity, bone mineral content (BMC), and lean soft tissue (LST) measured before and after a competitive season of Division I football. Body composition measures were conducted using single-frequency bioelectrical impedance analysis device (Quantum IV, RJL systems, Clinton MI). Pre- and post-season differences in anthropometrics and body composition were evaluated using repeated measures analysis of variance with Cohen's d statistics to estimate the magnitude of effect. Over the 15 weeks, participants experienced an average body mass loss of -0.4 (2.5) kg (d=0.17). BF% and FM increased on average by 1.4 (1.8)% (d=0.78) and 0.95 (1.8) kg, respectively. There were small increases in both android (0.08 (0.2) kg; d=0.36) and gynoid (0.10 (0.3) kg; d=0.38) fat throughout the season. Additionally, BMC showed a trivial increase of 0.002 (0.1) kg (d=0.02), despite a large decrease in mean LST (-1.40 (1.3) kg; d=1.06). Nutrition and physical activity level may have led to physical changes. Interventions designed to maintain adiposity throughout a season may be necessary. Additionally, resistance training programs may be appropriate to help maintain or increase LST throughout a season. Healthcare providers should be aware of changes in body composition which may lead to higher prevalence of injuries.

Firefighters (FFs) and law enforcement officers (LEOs) have heightened cardiovascular disease (CVD), with data suggesting that ≈45% of on-duty FF fatalities are related to CVD, while LEOs have a 1.7 times higher CVD prevalence than the general public. This study compared CVD risk biomarkers, fitness, and body composition between FFs and LEOs. Ninety-eight career, structural male FFs (age = 35.1±9.6 yrs; weight = 94.3±15.4 kg; height = 178.4±13.2 cm) and seventy-three career LEOs (age = 41.4±9.0 yrs; weight = 92.3±16.8 kg; height = 179.6±8.1 cm) from local departments were studied. Participants completed a maximal cardiopulmonary exercise test (CPXT), where VO_2max was estimated from the Foster equation. Fasted blood was collected to assess CVD risk biomarkers. Dual-energy X-ray absorptiometry assessed body composition, and waist and hip measures were taken. Analyses with and without women participants were conducted to assess differences in CVD risk biomarkers, fitness, and body composition between the FFs and LEOs. Effect sizes were calculated and reported as Cohen's d. Univariate general linear model (GLM) analysis of covariance (ANCOVA) were conducted to account for age as a covariate, wherein partial Eta squared (η_p ²) values were used to assess effect size for the GLM statistics. FFs had higher (p<0.05) CPXT exercise times (FFs: 10.9±1.6 min; LEOs: 10.3±2.0 min; d=0.366) compared to LEOs. FFs also had higher (p<0.05) advanced oxidation protein products (FFs: 134.8±90.1 μM; LEOs: 106.8±67.6 μM; d=0.342), blood cortisol (FFs: 14.2±5.0 μg/dL; LEOs: 12.5±5.6 μg/dL; d=0.325), and waist-to-hip ratios (FF: 0.95±0.06; LEO: 0.89±0.08; d=0.792). These findings suggest that while FFs demonstrated greater CPXT time-to-exhaustion, they also expressed higher stress and CVD risk biomarkers concentrations than LEOs. These data suggest that occupation-specific characteristics and stressors may play a role in the CVD risk profile of first responders.

Breakfast consumption has been shown to be an essential component to a healthy lifestyle in various populations, yet research in this area is limited among female athletes. This study aimed to examine the effect of breakfast consumption on collegiate female athletes during a resistance training session and their nutritional habits throughout the remainder of the day. Twenty-three female collegiate Division I athletes (basketball, volleyball, bowling, and soccer) during the offseason participated in this cross-over study. The study included three visits: baseline measures for heart rate (HR), blood glucose (BG), salivary cortisol (SC), and 5-repetition maxes for strength exercises; and two randomized conditions: a resistance training session with breakfast (experimental) and one with breakfast omission (control). For each condition, BG, HR, and SC was collected after a wait period which immediately preceded a resistance training session. Blood glucose, RHR, SC, heart rate recovery (HRR), and rating of perceived exertion (RPE) was collected after resistance training. A two-way multivariate analysis of variance (MANOVA) was used to examine how the condition (breakfast or breakfast omission) and time (pre and post) affected BG, HR, and SC. BG was more stable between pre and post in the experimental condition compared to the control. Lastly, a Wilcoxon signed-rank test showed that breakfast was associated with increased happiness and lower academic stress. This study showed that consuming breakfast could influence female collegiate athletes emotionally and physiologically, promoting further research as it could be of importance to female athletes, coaches, and administration.

Rowing requires strength, endurance, and technique, where stroke efficiency depends on body mechanics, movement sequencing, and stroke rate, which impact speed transfer. This cross-sectional study investigates the role of kinematic differences in stroke mechanics as a key component of performance analysis in Olympic and Traditional rowing. Thirteen elite national-level female rowers (age: 26.9 ± 5.1 years; body mass: 60.6 ± 6.9 kg; height: 166.7 ± 6.7 cm) performed three stroke-rate conditions on two ergometer setups: an Olympic rowing ergometer and a modified ergometer with a static seat replicating Traditional rowing. The stroke rates included 18 spm (120 s), 24 spm (100 s), and 30 spm (60 s), with 2-minute rest intervals between sets. Kinematic data, including leg and trunk angles at the catch and finish, as well as leg, trunk, and arm velocities, were captured using an automated analysis system. A two-way repeated measures ANOVA revealed significant interactions between rowing modality and stroke rate for leg catch angle (η ² =0.254; p=0.05), trunk finish angle (η ² =0.352; p=0.013), leg velocity (η ² =0.624; p<0.001), trunk velocity (η ² =0.665; p<0.001), and arm velocity (η ² =0.348; p=0.014). These findings emphasize distinct biomechanical patterns between modalities, which are crucial for technical optimization and individualized training. Performance analysis of angles and velocities provides valuable insights into improving rowing efficiency and addressing technical deficiencies in each modality.

Individuals after anterior cruciate ligament reconstruction (ACLR) are less physically active than their uninjured peers, but little is known about their sedentary behavior (SB). This study aimed to identify patterns of SB in individuals six and 18 months after ACLR. Eighteen individuals after ACLR wore accelerometers for one week during six- and 18-month post-operative assessments (83.3% female, 19.7±5.6 years old, BMI 23.9±kg/m²). The percentage of awake time spent in SB was estimated. A multilevel (two time points - six and 18 months), multidimensional (13 hours) functional principal component analysis generated two sets of unique personalized principal component scores: between-participant (person level principal components, PPC) and within-participant (follow-up level principal components, FPC). An exploratory analysis compared SB patterns with structural and symptomatic signs of knee health outcomes. Participants averaged 65.4±7.5% and 65.7±9.0% time in SB at six and 18 months after ACLR, respectively. The first PPC identified an overall pattern of high levels of SB throughout the day. The first FPC identified a pattern of decreased SB in the morning and increased SB in the evening 18 months after ACLR compared to six months. Our exploratory analysis identified a potential association between this first FPC and knee health symptoms 18 months after ACLR. Different SB patterns existed six months after ACLR. Our findings suggest the time of day when individuals after ACLR are most sedentary and provide a foundation to develop and test interventions to reduce time in SB by substituting periods of physical activity.

Performance in football depends on different dynamic interactions between players that occur at technical, tactical, physical, psychological, or sociological levels. The objective of this study was to analyze the evolution of match technical-tactical performance indicators according to age category in men's national football teams (U-17, U-20 and senior). A non-experimental retrospective observational design was used. Variables studied were ball possession, goal chances, shots off target, shots on target, corner kicks, effectiveness; goals, offsides, fouls committed, yellow cards, red cards, and second yellow cards. Data were drawn from 917 matches (195 senior, 369 U-20, and 353 U-17) played by teams from 97 nations. For the study of the differences between winners and losers, a T-test and a discriminant analysis were performed. To analyze the change between the different tournaments, a linear regression and its slope were used. Goal chances, shots on target, and effectiveness are the variables that best discriminated match winners. As players' ages increased, their effectiveness increased, there was a decrease in their shots and goal chances, and game actions were more balanced. The evolution of technical-tactical performance indicators between 2003-2009 and 2010-2019 showed a decrease in fouls committed and yellow cards for all categories. In general, the results show an evolution in the game towards strategies that seek to generate more effective situations with a greater chance of scoring. Data can serve as references to understand players' and teams' evolution and factors that correlate with winning (chances, shots on target, and effectiveness).

Knee injuries are very common in soccer players. High loads on the knee during landing or changes of direction can lead to a valgus shift of the knee, known as Dynamic Knee Valgus (DKV). Many studies have shown that a large shift in DKV is a predisposing factor for knee injuries and disease, such as anterior cruciate ligament injury (ACL), patellofemoral pain syndrome or osteoarthritis. Functional training could be a great tool to reduce DKV. Thus, in this pilot study, nine male youth soccer players (mean age: 16.4 ± 0.2 years) took part in six weeks of functional training program. DKV was measured in pre- and post-measurements during single leg squats using Kinect Azure camera with DynaKnee software. In addition, maximal voluntary muscle contraction (MVC) was measured using a dynamometer and muscle activation amplitude (MAA) was measured using electromyography. Data were analysed using a non-parametric Wilcoxon signed rank test to assess differences in DKV, MAA and MVC at a 5% significance level. Data showed a small improvement of DKV in the dominant leg. MVC increased slightly in all variables. The MAA of the involved muscles in the single-leg squat did not show a higher value, but rather a decreasing trend. However, none of the analyses showed significant changes. The small number of participants and the short duration of the training might have been a limiting factor. Further studies should repeat the procedure with a larger group of participants and a longer training period.

The purpose of this investigation was to determine inter-set and inter-session reliability of the HUMAC360 measures for duration (DUR), peak velocity (PV) and mean velocity (MV) across three segments of the bench press. Seventeen recreationally active adults participated in this investigation. During visit one, participants completed a bench press one-repetition maximum (1RM). Visits two and three consisted of two sets of three repetitions at 30%-, 50%-, 60%-, and 70 %-1RM. Segments were defined by dividing total displacement into equal thirds at the bottom (BOT), middle (MID) and top (TOP). Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were used to assess reliability while paired samples t-tests were used to identify differences between sets or sessions with significance set at p≤0.05. Excellent ICCs were present for PV and MV at most intensities in each segment between sets, while ICCs for DUR varied. MV and PV displayed excellent ICCs at lower intensities across segments between sessions, with decreases at higher intensities, while variable inter- session reliability for DUR was present across intensities and segments. The HUMAC360 reliably measured MV and PV during each segment across sets, though caution is warranted for DUR.

Cooling glabrous skin sites, such as the palms, can mitigate core body temperature rise and delay fatigue during physical activity, potentially enhancing performance. However, research on palm cooling (PC) in female athletes remains limited, and existing devices are often costly or impractical. This study evaluated the effects of PC using a novel, cost-effective portable device on repeat sprint ability in female collegiate athletes after a fatiguing protocol. Twenty female athletes (age: 20.1±1.4 years; height: 166.7±6.9 cm; mass: 66.6±9.8 kg; BMI: 24.0±3.9 kg/m²; body fat: 24.9±4.6%) participated in a randomized crossover study. Sessions included a modified Loughborough Intermittent Shuttle Test (LIST) followed by a 20-meter repeat sprint test. Athletes used either the PC device (7-15°C) during rest intervals or no cooling (NC). Physiological (heart rate, blood lactate), perceptual (RPE, thermal perception, affect), and performance outcomes (number sprints) were recorded. PC resulted in significantly more successful sprints (≥90% of maximum velocity) than NC (10.3±12.9 vs. 6.0±8.4; p=0.025). No significant differences were observed in perceptual or physiological measures (p>0.05). Palm cooling with a portable device improved repeat sprint ability in female athletes, supporting its use as a practical performance optimization strategy. Further research is warranted to investigate underlying mechanisms and applications across different sports and environmental conditions.

This study is the first to investigate the role of mental toughness (MT) in predicting strength and conditioning (S&C) performance outcomes and the impact of pressure training (PT) on MT development among NCAA athletes. A women's Division I field hockey team (n = 15) participated in five 1- hour sessions focused on psychological skills training to enhance MT, followed by two S&C sessions under PT conditions. Using the Mental Toughness Index, MT was assessed after the workshops/before PT and following PT. Regression analysis revealed that pre-PT MT scores predicted S&C performance outcomes during PT sessions (F(1, 16) = 4.67, p = .0499, 95% CI [0.154, 0.803]), with a positive correlation between MT scores and performance (R2 = 0.26, β = 0.07, 95% CI [0.00, 0.15]). A paired samples t-test revealed a significant increase in MT scores post-PT (t(12) = -3.34, p = .006, d = 0.93, 95% CI [-3.31, -0.69]), suggesting PT effectively enhances MT. PT sessions incorporated relevant-to-the-team demands and consequences, incidentally leading to increased athlete engagement and performance intensity. Overall, the findings demonstrate the relevance of PT as an innovative and practical tool for S&C coaches, offering initial evidence of its capability to enhance athlete development and optimize performance under high-stake conditions with strong ecological validity due to its application in real-world training environments. Future research should explore the longitudinal application of PT across larger samples, diverse sports, and its long-term effects on performance outcomes.