International journal of exercise science最新文献

The Bulgarian split squat (BSS) is a unilateral exercise that emphasizes hip extension more than knee extension, compared to other squat variations. This study aimed to (1) empirically verify the existence of the rear leg-derived moment (M_RL)-a theoretically plausible but previously untested external resistive hip moment acting against the net hip extension moment (M_HE) of the front leg-and (2) examine how stance width and forward trunk-leaning angles affect M_RL during the BSS. Nine trained male participants performed bodyweight BSS under two stance conditions (wide and narrow) and three trunk-leaning conditions (additional, natural, and reduced forward lean). A motion capture system and force platforms were used to calculate M_RL, head-arm-trunk segment-derived gravitational moment (M_HAT), and M_HE. M_RL substantially contributed to the total external resistance acting against the front hip extensors, ranging from 76 to 86 Nm in the wide stance and 49 to 71 Nm in the narrow stance, accounting for 70-97% and 62-98% of the total resistance (M_HAT + M_RL), respectively. In the narrow stance, M_RL increased significantly as the trunk became more upright. The combined M_RL and M_HAT closely matched M_HE, supporting the validity of the proposed mechanical model. These findings provide the first experimental evidence of M_RL as a key resistance factor in the BSS. Moreover, M_RL may enable practitioners to increase mechanical loading on the hip extensors while maintaining a more upright trunk posture, offering a potential advantage for strength training programs aiming to target the hip extensors with minimal forward trunk inclination.

Optimizing bike position is essential for enhancing cycling performance, improving comfort, and reducing injury risk. This study examined the acute effects of a bike fit using the idmatch^® system on power output, rate of perceived exertion (RPE), and discomfort in recreational cyclists. Twelve participants (10 males, 2 females; 37.0 ± 9.4 years) underwent an idmatch system bike fit, which employs three-dimensional motion capture to optimize rider position. Cyclists completed a six-second peak power test (PPT6) and a 20-minute functional threshold power (FTP) test before and after the fit. Performance metrics (power, cadence, and torque) and subjective measures (RPE, discomfort and region-specific pain) were recorded. Post-fit, peak power during the PPT6 test was 8.6% higher (pre: 952.1 ± 268.2 W; post: 1033.6 ± 263.6 W; p = 0.043). In the post-fit FTP test, average power output (pre: 190.0 ± 50.0 W; post: 198.7 ± 47.8 W; p = 0.047) and torque (pre: 15.6 ± 3.5 ft-lb.; post: 16.6 ± 2.2 ft-lb.; p = 0.035) were increased, while RPE (p = 0.029) and discomfort (p = 0.035) were decreased compared to pre-fit values. Performance improvements in both tests were positively correlated with the magnitude of saddle-to-handlebar distance adjustment (p < 0.05). Self-reported hand, foot, and hamstring pain trended lower following the bike fit (all: p = 0.125). These findings suggest that optimizing bike configuration using the idmatch system acutely improves power production and reduce discomfort in recreational cyclists. Motion-capture-based fitting systems may offer a practical solution for enhancing cycling performance.

This study aimed to establish whether a laboratory (lab) based 3-minute all-out (3MT) protocol and a field-based 3MT protocol would yield similar peak power (P_max), critical power (CP), and curvature constant (W') profiles and the implications of parameter estimation for informing a 40-km time trial (TT) performance. Nine competitive male cyclists (mean ± SD: age 36.5 ± 10.42 y, mass = 80.5 ± 10.6 kg, height 1.8 ± 0.1 m) completed two 3MTs on separate days, as well as a 40-km time trial. Both lab and field-based protocols evoked similar CP (p = 0.160) and W' (p = 0.200) profiles, but P_max (p = 0.012) may be more sensitive to biomechanical disparities and testing environment. Strong positive associations were observed with W'-kinetics (r = 0.73) and W' (r = 0.83) and moderate-to-strong negative associations with mean TT power (r = -0.75) and CP (r = -0.68). TT power outputs occur at 59-65% of CP, and finishing times appear to be informed by CP, W' and P_max with high degrees of accuracy (R2 > 0.90). Although TT performances occur predominantly within the moderate-to-heavy intensity domains, the mean intensity from a cardiovascular and core temperature perspective was high (i.e., ~90% HR_max; ~39°C). TT performances appear to be accurately informed by CP, W' and P_max, with W' dominating the predictive capacity associated with longer TT performances.

Blood flow restriction (BFR) combined with exercise has been shown to enhance muscle hypertrophy, strength, and aerobic capacity. While previous studies have evaluated the use of BFR among various practitioners, none have investigated its use exclusively among licensed U.S. physical therapists (PTs). A cross-sectional survey was distributed electronically to licensed U.S. PTs. Participants were required to use BFR currently in clinical practice. Survey items included respondents' demographics, practice setting, exercise mode, the type of BFR equipment used, and adverse events. A total of 134 licensed PTs from 20 states completed the survey. BFR was most commonly used in outpatient orthopedic settings, primarily in conjunction with resistance exercises. The Delfi unit was the most frequently used device (64%). No major adverse effects reported (e.g., thrombosis, rhabdomyolysis, nerve damage). Minor adverse effects, including dizziness, numbness, nausea, and delayed onset muscle soreness, were reported by 8% of participants (n = 11). This survey found no major adverse effects and a low prevalence of minor, transient adverse effects. These findings are consistent with previous BFR safety literature and provide a foundational overview of BFR practices among U.S. PTs.

This longitudinal study explored entry route- and age-related fitness differences between cadet (CR) and general population (GR) firefighter recruits. Fitness data were collected from eight separate firefighter recruit academy cohorts (N = 317; 122 CR, 195 GR; 27.17 ± 7.58 yrs, 177.30 ± 8.72 cm, 88.65 ± 17.78 kg). In the first week of the academy, recruits completed an assessment battery including: body composition via skinfold measures to estimate body fat (BF, %) and fat-free mass (FFM, kg); aerobic fitness (VO_2peak, mL· kg^-1· min^-1) and heart rate recovery (HRR_1min, %) estimated from the five-minute Forestry Step Test; movement quality via a squat-based movement screen (MES, 0-100); muscular strength via the sum of right and left handgrip (SHG, kg); and muscular endurance via a two-minute push-up test. Due to non-normally distributed data, non-parametric statistical tests were used. Wilcoxon rank-sum tests (α < 0.05) evaluated fitness differences between entry routes. Kruskal-Wallis tests evaluated differences between four age groups: A1 (19-21 yrs), A2 (22-29 yrs), A3 (30-39 yrs), and A4 (40+ yrs). CR had significantly (p < 0.05) lower age, BM, BF, and FFM, but greater MES, VO_2peak, HRR_1min, and PU. A1 had lower BM, BF, and FFM; and greater VO_2peak, HRR_1min, and PU (p < 0.01) than all other ages. The range of fitness in recruits upon academy entry necessitates careful programming to support optimization of fitness in all recruits, regardless of age. The fitness elements of an academy may present opportunities to build health and fitness literacy, necessary for career longevity.

The intensity of aerobic exercise is influenced by maximum heart rate (MHR), which can be assessed through an incremental exercise test. However, this method requires specialized equipment and a level of fitness that individuals who are sedentary or overweight may lack. Therefore, estimating MHR using formulas is essential. Various methods exist to calculate MHR, but their effectiveness in real exercise programs for obese individuals remains unclear. This study aimed to investigate the effects of aerobic exercise using different intensity calculation methods, specifically comparing Fox's and Tanaka's maximum heart rate (MHR) equations, as well as the Percentage and Karvonen methods for target heart rate (THR). Seventy-eight men aged 20 to 30 with a body fat percentage of over 20% were divided into one control group and four aerobic exercise groups. EG1 and EG3 used Fox's and Tanaka's equations for MHR and THR from the percentage, while EG2 and EG4 applied the Karvonen method for THR. Participants engaged in 45 minutes of moderate-intensity walking or running on a treadmill four days a week for 12 weeks. Body weight, body fat percentage, BMI, resting heart rate (RHR), and VO₂ max were measured at baseline and after the intervention. After 12 weeks, all exercise groups demonstrated significant improvements in VO₂ max, as well as reductions in body weight, body fat percentage, BMI, and resting heart rate (RHR), whereas the control group showed no changes. No significant differences were found among the exercise groups. Aerobic exercise at various intensities effectively enhances cardiovascular fitness and body composition in obese individuals, indicating that these methods are equally beneficial.

The objective was to investigate screen time (ST) and objectively measured sleep quality in college students. Participants were undergraduate students attending a large metropolitan public university in the southeastern U.S. Participants wore accelerometers on their wrist for 24hr/day for 14 days to capture sleep outcomes, and completed a survey reporting ST duration. Analyses explored weight-status, race/ethnicity, and sleep patterns (presence of daytime sleep) differences among students. Participants (n=29, 86% female, ~21.5 years old, 38% White, 35% Overweight/Obese) slept for an average of 433.8 minutes/night, reported 419.1 minutes of daily ST, and 112 minutes of ST after 10:00PM. College students with daytime sleep (i.e., napping) reported approximately -92 minutes less of daily ST than peers (p=0.04; effect size=0.86). Further studies in larger, diverse samples are needed to explore ST and sleep, specifically the causal relationship and its potential to impact the health of college students at greatest risk of poor health outcomes.

Motion analysis is used to measure proper bicycle fit, avoid injury, and improve cycling performance. Small changes in position can impact joint kinematics and risk for overuse injury. Concerns regarding the often-used biomechanical model Plug-in-Gait (PIG) resulted in the creation of Conventional Gait Model 2 (CGM2). This study aims to compare kinematic outputs of these two models for cycling biomechanics plus between-day reliability of each model. Thirty-five participants participated in two experimental sessions. PiG and CGM2 marker sets were applied, and data was collected while cycling between 80-90 rpm. Model outputs were compared using session one kinematic data. Reliability tests used session one and session two data. Differences in kinematics were found between models for hip flexion (CGM2 - PiG mean difference = -8.2° ± 5.2°, p < .001), hip frontal plane (mean = 5.4 ± 4.1°, p < .001), hip transverse plane (mean = -5.3° ± 11.6°, p = .011), knee extension (mean = 1.8° ± 4.2°, p = .015), knee frontal plane (mean = -10.8° ± 9.6°, p < .001), dorsiflexion (mean = -1.7° ± 3.6°, p = 0.005), and plantarflexion (mean = 3.3° ± 5.4°, p < 0.001). CGM2 ICCs were good-to-excellent (> 0.75) for all motions except frontal plane knee motion. PiG ICCs were > 0.75 only for ankle dorsiflexion and plantarflexion. If CGM2 is used to assess bicycle fit, reference values should be adjusted based on the difference between models to ensure an appropriate fit is obtained. CGM2 has better between-day reliability, therefore practitioners may consider using CGM2 for serial fit sessions.

Accurate physical activity (PA) measurement is crucial for public health surveillance. While self-report questionnaires are commonly used, they have limitations, especially in young children. An affordable and user-friendly device like Feelfit® offers a promising alternative particularly for countries with limited research resources. This study aimed to evaluate Feelfit®'s performance against the widely used ActiGraph® accelerometer in measuring PA among children. A quasi-experimental design was applied. Thirty-nine children (19 boys; 20 girls; aged 11.4 ± 0.5 years) wore both Feelfit® and ActiGraph® during sequentially specified activities of varying intensity ranging from sedentary to vigorous. Data were analysed using paired t-tests, Bland-Altman plots, and intra-class correlation coefficients (ICCs) to assess agreement, precision, and reliability. Feelfit® showed good agreement with ActiGraph® for moderate-to-vigorous PA (MVPA) but overestimated sedentary time and underestimated light PA. It demonstrated better precision for MVPA but low reliability for light PA. Intra-class correlation coefficients were moderate for MVPA (ICC = 0.43), but poor for sedentary time (ICC = 0.11). Feelfit® is a suitable option for measuring MVPA in children, offering acceptable validity and reliability compared to ActiGraph®. However, improvements are needed for accurate measure of sedentary and light activities. Despite these limitations, Feelfit®'s affordability and ease of use make it a valuable tool for use in small- to large-scale research and in resource-limited settings.

Although acutely donning compression garments improves several markers of athletic performance, the effects of training in compression garments remains largely unexplored. Thus, this study aimed to determine the effects of exercise training while donning a novel full-body compression garment on multiple measures of anaerobic performance. Sixteen sedentary males (age: 21±3 y; BMI: 25±3 kg/m²) completed 4 weeks of training with (CG; n=8) or without (CON; n=8) a novel full-body compression garment. Subjects performed a 40m sprint (time and velocity), a 5-repetition maximum barbell back squat (barbell weight and serratus anterior activity), a countermovement vertical jump (VJ; displacement, force, power, velocity, and acceleration), and a Wingate Anaerobic Test (WAnT; peak power, mean power, and fatigue index) before (PRE) and after (POST) training. Data are presented as mean ± SD changes from PRE and were analyzed via two-way repeated measures ANOVAs. CG showed a significant increase when compared to CON for the change in sprint velocity (-0.68±0.26 m/s, P = 0.014), VJ velocity (+0.15±0.07 m/s, P = 0.033), WAnT relative peak power (+0.88±0.49 W/kg P = 0.018), WAnT absolute mean power (+62.37±52.11 W, P = 0.006), and WAnT relative mean power (+0.83±0.53 W/kg, P = 0.004). While there were statistically significant improvements from PRE to POST in other measures, only the aforementioned five variables demonstrated intergroup significance. Overall, donning this novel full-body compression garment during training led to enhanced performance in specific anaerobic measures when compared to not training in the garment.