The present study examined the effects of four days of training on peak torque (PT), muscle thickness (MT), and electromyographic co-activation (Co- Act). Ten untrained women (age=21.6±1.0 years) completed four days of maximal, reciprocal, concentric, isokinetic forearm extension (FE) and flexion (FF) training with six sets of 10 repetitions at 180°·s-1. The subjects completed pre-training and post-training visits, which consisted of collecting FE and FF PT at 180°·s-1, triceps brachii (TB) and biceps brachii (BB) MT, and FE and FF EMG Co-Act (ratio of antagonist to agonist). Separate two-way ANOVAs were used to analyze PT (Movement×Time), MT (Muscle×Time), and EMG Co-Act (Movement×Time). Individual changes from pre-training to post-training were compared to minimal difference (MD) values. For PT, a significant (p=0.040) main effect for Time indicated an increase from pre-training (19.53±5.45 N·m) to post-training (22.47±5.93 N·m). Ten and 20% of the subjects exhibited changes greater than the MD for FE and FF PT, respectively. There was no interaction (p=0.743) or main effect of Time (p=0.106) for MT. There was a decrease (p=0.011) in FF EMG Co-Act (-7.78%), whereas FE EMG Co-Act (+2.32%) did not change (p=0.598). Zero subjects exhibited changes greater than the MD for FF EMG Co-Act. The mean increases in PT were likely due to neural adaptations since there were no changes in MT. Although a mean decrease in FF EMG Co-Act suggested it may have contributed to mean increases in FF PT, none of the subjects expressed "real" changes (change values greater than the MD) in FF EMG Co-Act.
The purpose of this study was to determine the feasibility of heart rate (HR) monitoring using an optical monitor (OHR) across different swimming strokes and intensities. Nineteen collegiate swimmers (7M, 12F) completed two swimming protocols (P1: nine 75m freestyle swims at three intensities, P2: two 100m swims using their preferred stroke). During P1, four swimming bouts were completed at light intensity (HR 145-155 beats per minute [bpm]), three at moderate intensity (HR 155-170bpm) and two at vigorous intensity (HR > 170bpm). During P2, participants completing one swimming bout using their preferred stroke (freestyle [n=7], backstroke [n=5], breast stroke [n=4], and butterfly [n=3]) at moderate intensity and one vigorous intensity with one-minute rest between each swim. A repeated measures ANOVA (RM ANOVA) with post hoc analysis was completed between the OHR and a traditional chest monitor (THR) with significance set at p<0.05. There was an overall significant difference between mean OHR and THR (OHR: 150.7 ± 17.0 vs. THR: 155.9 ± 19.0 bpm, p=0.02) and significant differences during the recovery stage between P1 and P2 (OHR: 126.1 ± 17.8 vs. THR: 122.3 ± 18.0 bpm, p=0.007) and the first 100m swim of P2 (OHR: 148.3 ± 21.3 vs. THR: 159.1 ± 20.1 bpm, p=0.002). The OHR monitor captured 99.9 ± 0.1% of the HR data whereas the THR captured only 58.98 ± 31.3% of the participants' HR data. The OHR significantly underestimated HR compared to the THR but more consistently captured HR than the THR throughout the duration of the swim test.
Understanding the distinct biomechanical and neuromuscular demands of aquatic sports is key to developing targeted training strategies for youth athletes. This study compared neuromuscular profiles between male youth Thai swimmers and Optimist sailors by examining the Dynamic Strength Index (DSI) in upper and lower limbs. A secondary aim was to assess the relationships between the biological maturity, estimated via 2D:4D digit ratios and predicted peak height velocity (PHV) and neuromuscular performance. Forty male athletes (n = 20 per group; mean age: swimmers = 12.9 ± 0.7, sailors = 13.3 ± 0.8 years) completed ballistic (Countermovement Jump, push-up) and isometric (Isometric Mid-Thigh Pull, grip strength) tests. Swimmers showed significantly greater neuromuscular output in both limbs, with higher CMJ peak force (mean diff: 339.78 N; p < 0.001, d = 1.64) and push-up force (mean diff: 135.26 N; p < 0.001, d = 1.51), resulting in higher lower-limb DSI (0.86 vs. 0.70; p < 0.01, d = 0.89). Two-way ANOVA revealed a significant limb effect (p < 0.001, η2 p = 0.631) and a sport × limb interaction (p = 0.002, η2 p = 0.104), indicating sport-specific neuromuscular adaptations. Correlational analysis showed positive associations between lower-limb DSI and right-hand digit lengths and a negative relationship with PHV. These results underscore the importance of tailoring strength training to the sport-specific and maturational profiles of male youth athletes.
Cardiovascular diseases (CVDs) represent a leading global health burden, with risk factors often emerging during college years. Traditional assessment methods like Body Mass Index (BMI) have significant limitations in predicting health outcomes. This study evaluated the relationship between Fitness-Fatness Index (FFI) and cardiovascular outcomes in college-aged students compared to traditional measures. A correlational-predictive non-experimental survey was conducted with 218 healthy, non-smoking young adults (109 male, 109 female; age 20.8±2.9 years). Participants underwent comprehensive anthropometric assessments, body composition analysis, aerobic fitness tests, and cardiovascular measurements, including brachial/central blood pressure and arterial stiffness parameters. Multiple linear regression analysis revealed that metabolic equivalents (METS) were the strongest predictor of arterial stiffness parameters, with the highest beta coefficients for augmentation pressure (β=-0.407, p=0.002), augmentation index (β=-0.398, p<0.001), and pulse wave velocity (β=-0.234, p=0.006). The waist-to-height ratio was the strongest predictor of adjusted brachial systolic blood pressure (β=0.159, p=0.016), while FFI was the strongest predictor of central diastolic blood pressure (β=-0.306, p<0.001). These findings indicate cardiorespiratory fitness is a key determinant of arterial stiffness in college-aged individuals, challenging the hypothesis that FFI would outperform traditional measures. Incorporating both METS and FFI may provide more comprehensive cardiovascular risk assessment in this population.
Neural mobilization (NM) is an acute bout method that aims to directly or indirectly affect the mechanical and physiological properties of the nerve tissue or surrounding structures using manual techniques or exercises. This study aimed to evaluate the immediate effects of incorporating NM into warm-up routines on flexibility, balance, and performance compared with static stretching (SS) and dynamic stretching (DS). Thirty-six amateur soccer players aged 18-25 participated in a randomized controlled, assessor-blinded study. Participants sequentially performed a 5-minute standardized warm-up, group-specific acute bout (SS, DS, or NM), and a 5-minute cool-down. Pre- and post-test assessments consisted of the straight leg raise test (flexibility), Y balance test (balance), single-leg forward hop test (performance), T-test (agility), and BlazePod reaction time. All groups showed significant post-test improvements in flexibility, balance, and performance (all p < 0.05, η2 = 0.06-0.18). The NM group demonstrated a greater reduction in agility T-test time (p = 0.028, η2 = 0.10), while no significant agility changes were observed in the other groups (p > 0.05). Intergroup analysis revealed greater improvement in the anterior reach direction of the Y balance test for the NM group (p = 0.038, η2 = 0.19). No significant group-by-time interaction was found (p > 0.05). These findings suggest that NM, by targeting the neural system rather than muscle tissue, may provide additional neuromechanical benefits and enhance balance performance during warm-up in soccer players.
This study aimed to investigate the sensitivity of low-frequency fatigue (LFF) in high-level road cyclists following two distinct cycling efforts: a 30-minute maximal effort (30'TT) and a 4-minute maximal effort (4'TT). Twenty-one participants were included in this study (age: 22.8 ± 4.8 years; height: 169.9 ± 3.5 cm; body mass: 68.5 ± 8.5 kg), and LFF, perceived fatigue and muscle soreness were monitored at baseline, 30 minutes and 24 hours post-fatigue protocol. Linear mixed model analysis was employed to assess the changes caused by protocol, time, and limb dominance, and a repeated-measures correlation was used to assess the association between LFF and perceived fatigue or muscle soreness. Significant fatigue was induced by both protocols (p < 0.001), with LFF scores returning to baseline after 24 hours. Notably, following the fatigue protocols, a significantly lower LFF score was observed after the 4'TT compared to the 30'TT (d = 0.39, p = 0.032). Furthermore, a large and significant association between LFF scores and perceived fatigue (rmcorr = -0.5, p < 0.001) was identified, as well as a weak and significant association between LFF and perceived muscle soreness (rmcorr = -0.28, p < 0.001). Taken together, these findings seem to support LFF as a sensitive, field-based tool for monitoring acute peripheral fatigue following cycling efforts.
Recent studies have verified the use of the stretch-shortening cycle (SSC) during countermovement pull-ups (CMPs); however, the relationship between CMP performance and maximal strength remains unclear. With the increasing popularity of training guided by mechanical variables, quantifying SSC-related contributions and identifying key CMP variables may provide insights into innovative pull-up training. This study examined correlations between mechanical variables during CMPs and pure concentric pull-ups (PCPs) and maximal muscle strength in athletes, to elucidate the characteristics of CMPs. Fifty male collegiate athletes participated. A linear position transducer measured peak velocity (Vmax), mean velocity (Vmean), mean power, and time to peak velocity (time to Vmax) during CMPs and PCPs. Lat pulldown isometric maximal strength (LP-IMS) was evaluated using a hand-held dynamometer. To control for body weight, residuals from regressions with body weight as the independent variable were analyzed. Spearman's rank correlation coefficients were calculated to evaluate relationships between mechanical variables and maximal strength. Vmean (r s = 0.511) and Vmax (r s = 0.544) of PCPs exhibited significant strong positive correlations with LP-IMS, whereas time to Vmax correlated moderately negatively (r s = -0.319). Conversely, CMP Vmean demonstrated a weak positive correlation with LP-IMS (rs = 0.279), with no significant correlation for Vmax. CMP time to Vmax was strongly negatively correlated with LP-IMS (r s = -0.570). These findings indicate that Vmax and Vmean in CMPs are weakly associated with strength, suggesting the involvement of non-strength factors, such as SSC utilization. This study provides insights into upper-limb SSC and may guide training protocols for pulling exercises.
Sleep is particularly important for student-athletes in the pursuit of both academic success and athletic performance. The primary aim of this study was to investigate the relationship between training load (TL), perceived cognitive workload, and sleep in varsity male volleyball athletes. The secondary aim was to understand the physiological and cognitive mechanisms leading to sleep disturbances following a match. Twelve varsity players on a men's university volleyball team were examined for 12 weeks of the competitive season. Sleep, internal TL and cognitive load were assessed using daily surveys. External TL was assessed using wearable jump monitors during training and matches. Participants filled the Pre-Sleep Arousal Scale to assess pre-sleep arousal and the Ottawa Mental Skills Assessment Tool to assess mental skills after eight matches. Our results show that the perceived cognitive load had a negative impact on total sleep time (p = 0.003) and sleep quality (p = 0.048). Moreover, internal TL had detrimental effects on sleep quality (p = 0.04). We also observed a negative association between cognitive pre-sleep arousal and sleep efficiency (p = 0.004). and sleep onset latency (p = 0.03). Finally, no effect was found between mental skills and post-match sleep. Our results suggest that assessing perceived cognitive workload is essential when monitoring student-athletes. Moreover, higher sleep onset latency and lower sleep efficiency were associated with elevated levels of cognitive arousal supporting the idea that post-match sleep difficulties are due to cognitive arousal rather than physiological arousal.
Obesity prevalence has rapidly increased in the United States to over 40%. The low-grade chronic inflammation with obesity is linked to increased risk of cardiovascular disease. Impairment of endothelium-dependent vasodilation is one of the first subclinical stages in the atherosclerotic process. Although some information exists on the effects of exercise training on endothelial function, there is limited data on the acute effects of maximal exercise on endothelial function in obese individuals. Study Objective: This study aimed to investigate the effects of maximal aerobic exercise on endothelial function, specifically serum C1q-TNF-related-protein-9 (CTRP9), serum total nitric oxide (NOx), and brachial artery flow-mediated dilation (FMD) in obese and normal-weight individuals. Hypothesis: We hypothesized that increased serum CTRP9 following maximal aerobic exercise would be observed in both obese and normal-weight participants; however, only the normal-weight participants would have increased FMD and serum NOx in response to exercise. Methods: Sixteen young male participants (9 obese and 7 normal-weight) participated in a maximal graded exercise test on a treadmill. CTRP9, NOx, and FMD measurements were taken prior to, immediately following exercise, and 1 hour and 2 hours into recovery. Statistical analyses included repeated measures ANOVA and Pearson correlations. Results: There was a significant time effect for serum CTRP9 following maximal exercise (p=0.049) with a significant decrease in serum CTRP9 in both groups from immediately after exercise to 1 hour after exercise (p=0.007). There was also a significant time effect for serum NOx following exercise (p=0.04) with a significant increase in serum NOx levels in both groups from baseline to immediately after exercise (p=0.018) that returned to baseline during recovery. FMD did not significantly change across time (p=0.452), although obese participants had lower FMD vs. normal-weight participants (p=0.017). Additionally, CTRP9 was positively correlated with NOx across all timepoints (r=0.273, p=0.029). Conclusions: Maximal intensity exercise significantly elevates NOx, transiently decreases CTRP9 and does not alter FMD with similar responses between obese and normal-weight participants. The results from this study provide a foundation for additional examination of the acute impacts of maximal intensity exercise on endothelial function in individuals with obesity. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
