Frontiers in Physiology最新文献

Objective: This study compared the effects of Flywheel Resistance Squat Training (FRST) vs. Traditional Resistance Squat Training (TRST) on lower body strength in female collegiate basketball players.

Methods: Nineteen participants were randomly assigned to either the FRST group (n = 9) or the TRST group (n = 10) through a random number draw. Both groups underwent a 6-week intervention with training sessions conducted twice a week. The FRST group utilized an inertia of 0.075 kg ·m², while another group trained at 80% of their one-repetition maximum (1RM). Each training session consisted of 4 sets of 8 repetitions with a 3-minute rest between sets. Both groups performed standardized warm-ups and stretches before and after each training session. The effectiveness of the training methods was assessed through the Countermovement Jump (CMJ), Reactive Strength Index (RSI), Eccentric Utilization Ratio, Running Vertical Jump, and 1RM squat.

Results: The FRST and TRST groups showed differences within groups in both CMJ and 1RM squat (p < 0.01), with the FRST group demonstrating moderate effect sizes in CMJ (Hedges' g = 0.59) and 1RM (Hedges' g = 1.01). However, there were no differences between groups (p > 0.05). The Eccentric Utilization Ratio showed a small effect size (p = 0.78; ${\eta }_p^2=0.01$ ). Additionally, Reactive Strength Index and Running Vertical Jump exhibited low test-retest reliability.

Conclusion: The two groups did not exhibit a statistically significant difference. Nonetheless, both FRST and TRST demonstrated positive effects on 1RM squat and CMJ performance compared to baseline values for each method. Therefore, flywheel resistance training can be considered an effective alternative to traditional resistance training for enhancing strength levels in female basketball players.

Contrast-induced acute kidney injury (CI-AKI) has emerged as a global public health concern, ranking as the third most prevalent cause of hospital-acquired acute kidney injury, which is related to adverse outcomes. However, its precise pathogenesis remains elusive. Consequently, researchers are dedicated to uncovering CI-AKI's pathophysiology and signaling pathways, including inflammation, oxidative stress, apoptosis, and ferroptosis, to improve prevention and treatment. This review thoroughly analyzes the signaling pathways and their interactions associated with CI-AKI, assesses the impact of various research models on pathway analysis, and explores more precise targeted treatment and prevention approaches. Aims to furnish a robust theoretical foundation for the molecular mechanisms underpinning clinical treatments.

Introduction: This study aims to investigate the differences in functional movements and core muscle activities between experienced and novice practitioners during Pilates exercises.

Methods: Thirty-eight participants were recruited for the study, comprising 19 experienced and 19 novice Pilates practitioners. Participants performed functional movement screening (FMS) tests and six Pilates exercises at the basic, intermediate, and advanced levels. Surface electromyography (EMG) was utilized to measure muscle activity at four sites: right rectus abdominis (RA), external oblique (EO), multifidus (MU), and longissimus (LO). Mean EMG activity, co-contraction indices, and duration of core muscle activation were analyzed using independent t-tests to examine the differences between groups. Cohen's d was used to calculate effect sizes based on the standard deviations of the groups. Statistical significance was set at p < 0.05.

Results: The experienced practitioners scored significantly higher in total FMS scores and in four sub-units of the FMS scores compared to the novice group (p ≤ 0.01). Mean EO EMG activity was also significantly greater in experienced practitioners during all Pilates exercises (p < 0.05). Additionally, the RA/EO co-contraction index was higher in experienced practitioners during the 'double leg stretch' exercise (p = 0.02).

Conclusion: The results suggest that experienced Pilates practitioners have superior functional movement abilities and greater core muscle activation, particularly in the EO muscle group, compared to novice practitioners. These findings may assist Pilates instructors in refining instructional strategies to cater to different skill levels and enhance training effectiveness.

Objectives: Inertial training, also called flywheel training is more and more popular among sportsmen. The available data concerning the effectiveness of inertial training compared to conventional resistance strength training are contradictory. The aim of this study was to compare the impact of inertial training (IT) vs. traditional gravity-dependent resistance training (TRT) on elbow flexor and knee extensor strength.

Methods: Twenty-six young, recreationally active males were randomized into IT group (n = 13) or TRT group (n = 13). Both groups performed strength training three times a week for 6 weeks. Before and after training, the maximum force of the trained muscles was evaluated under training conditions (one repetition maximum under gravity-dependent conditions and maximal force under inertial conditions) and isometric conditions. Countermovement jump, squat jump, pull-up test, and limb circumference were also evaluated.

Results: Elbow flexor muscle strength and arm circumference increased significantly in both IT and TRT over the course of training. There were no significant differences in relative muscle strength increases between groups. Knee extensor muscle strength also improved significantly in IT, regardless of the tested conditions, while TRT showed significant changes in one repetition maximum and isometric force but no significant changes in force obtained under inertial conditions. Thigh circumference increased in IT (P ≤ 0.05) but was unchanged in TRT. Jumping abilities improved significantly in both groups, without any differences between groups.

Conclusion: We cannot confirm the superiority of inertial training over traditional resistance training definitively. Nevertheless, inertial training had a slight advantage over traditional resistance training when knee extensor muscle training was considered.

Purpose: This study examined the physiological effects of 12 weeks of detraining and retraining in a highly trained master triathlete (age 53.8 years).

Methods: Variables associated with swimming, cycling, and running performance, including $\dot{V}$ O_2max, peak power output (PPO), gross cycling efficiency (CE), running maximal aerobic velocity (MAV), running economy (RE), muscle strength, and body composition were assessed before the last race of the season (baseline), after 12 weeks of detraining, and after 12 weeks of retraining.

Results: Detraining resulted in a 9.1% and 10.9% decrease in relative $\dot{V}$ O_2max for cycling and running, respectively. PPO and MAV declined by 12.7% and 8.6%, respectively. After detraining, CE decreased by 6.2%, and RE was 22% higher than the baseline. The maximal strength capacity of the knee extensor muscles decreased by an average of 8.2%. Body fat percentage increased from 10.5% to 13.8%, while lean mass decreased by 2.2 kg. After retraining, almost all variables returned to baseline or even slightly increased, except RE and lean mass, which did not return to baseline.

Conclusion: After 12 weeks of detraining, a lifelong master triathlete can regain his cardiorespiratory fitness (i.e., $\dot{V}$ O_2max) with 12 weeks of progressive and structured retraining, but his running economy and lean mass remain slightly depressed.

Aim: Assessment of blood pressure during exercise is routine in athletes, but normal values remain equivocal. This study examines the response of systolic blood pressure (SBP) to exercise in a large cohort of athletes and establishes normative values by sex and age.

Methods: Competitive athletes free of cardiovascular disease underwent pre-participation exercise testing on a bicycle ergometer. Resting (SBPrest) and peak blood pressure (SBPpeak), heart rate (HRrest and HRpeak), and power output (WR) were recorded. Workload indexed values were calculated.

Results: The cohort included 12,083 athletes (median age 15 years, 26.9% female). Median peak exercise SBP was similar between sexes, but WR-indexed measures including SBP/WR ratio and SBP/(WR/kg) slope were higher in females (0.9 vs. 0.7, p < 0.001; 10.94 vs. 9.52, p < 0.001). Univariate analyses revealed significant associations between SBPpeak and several predictors, including sex, age, weight, height, SBPrest, DBPrest, HRrest, HRpeak, and WR (all p < .001). Multivariate analysis showed that SBPrest (beta = 0.353, 95% CI [0.541, 0.609], p < 0.001), height (beta = 0.303, 95% CI [0.360, 0.447], p < 0.001), WR (beta = 0.171, 95% CI [0.029, 0.045], p < 0.001), and age (beta = 0.093, 95% CI [0.162, 0.241], p < 0.001) were the strongest predictors of SBPpeak.

Conclusion: This study provides reference values for the interpretation of SBP responses to exercise in athletes. Multivariate analyses highlight the complex interplay of factors influencing peak SBP, including SBPrest, height, WR, age, DBPrest, sex, endurance sport category, and weight. In future studies, these findings may inform the development of personalised training strategies and risk stratification models in athletic populations.

Objective: The purpose of this study was to compare the impact of unilateral (U) and bilateral (B) contrast training on lower limb explosiveness, agility, and balance in college basketball athletes. Methods: Twenty male college basketball players were randomly assigned to either a unilateral group (U, n = 10) or a bilateral group (B, n = 10). Both groups underwent an 8week strength training program, with sessions held twice a week. The unilateral group performed six Bulgarian split squats and ten reverse lunge jump squats, while the bilateral group performed six barbell rear squats and ten double-leg vertical jumps. To comprehensively assess the training effects, the study utilized one-repetition maximum (1RM), countermovement jump (CMJ), 20m sprint, and single-leg hop tests to evaluate explosive power; the 505 and t-test to assess change-of-direction ability; and the Y-balance test (YBT) to evaluate dynamic balance. Paired sample t-tests were used to evaluate within-group changes, and a 2 (pre- and post-) × 2 (experimental and control groups) repeated measures analysis of variance (ANOVA) was used to assess between-group differences. Results: Within-group comparisons indicated that both unilateral and bilateral contrast training significantly improved all performance metrics. Between-group comparisons revealed that bilateral training was superior to unilateral training in improvements in 1RM and CMJ (p > 0.05) (growth rate of 1RM: B: 8.4%, U: 5.15%; growth rate of CMJ: B: 15.63%, U: 6.74%). Unilateral training showed greater improvements in the 20m sprint, dominant leg single-leg hop, YBT left, and YBT right (p > 0.05) (growth rate of 20m sprint: B: 5.43%, U: 10.41%; growth rate of advantage foot touch high: B: 4.56%, U: 9.35%; growth rate of YBT left: B: 3.77%, U: 8.53%; growth rate of YBT right: B: 4.72%, U: 13.8%). Unilateral training also significantly outperformed bilateral training in non-dominant leg single-leg hop, t-test, 505 left, and 505 right improvements (p < 0.05). Conclusion: Unilateral contrast training may offer advantages for enhancing change-of-direction ability and explosive power in the non-dominant leg, and it may also provide benefits for improving short-distance sprinting ability, explosive power in the dominant leg, and dynamic balance. In contrast, bilateral contrast training appears to be more effective for enhancing bilateral explosive power and may be more advantageous for increasing maximal strength.

The lateral habenula (LHb) has been implicated in stress coping and autonomic control. The LHb regulates the midbrain system of monoamine neurotransmitters such as dopamine, serotonin, and noradrenaline. However, how the LHb regulates autonomic cardiovascular control in stressful situations is unclear. In this study, we examined the participation of the midbrain dopaminergic system in the cardiovascular response elicited by activation of the LHb. We used urethane-anesthetized Wistar male rats. We performed electrical stimulation of the LHb to observe changes in heart rate and blood pressure. Stimulation of the LHb caused bradycardia and a pressor response. Application of a nonselective dopamine receptor antagonist attenuated both the heart rate and the blood pressure changes induced by the LHb. We also tested the effects of blockade of dopamine receptor subtypes in the LHb-induced cardiovascular responses. Application of selective dopamine D₁/D₅, D₂/D₃, or D₄ receptor antagonists attenuated the LHb-induced pressor response but did not change the HR response. Furthermore, we examined the effect of inactivation of the ventral tegmental area (VTA) on the cardiovascular response induced by LHb stimulation. Inactivation of the VTA turned bradycardia into tachycardia caused by the LHb stimulation and attenuated the pressor response. Our results indicated that regulation of the dopaminergic system by the LHb mediates the generation of the autonomic cardiovascular response. Dopamine D₁-like and D₂-like receptors mediate the sympathoexcitation resulting from the activation of the LHb. The VTA is one of the dopaminergic origins related to the cardiovascular response originating from LHb activation.

As delayed treatment of septic shock can lead to an irreversible health state, timely identification of septic shock holds immense value. While numerous approaches have been proposed to build early warning systems, these approaches primarily focus on predicting the future risk of septic shock, irrespective of its precise onset timing. Such early prediction systems without consideration of timeliness fall short in assisting clinicians in taking proactive measures. To address this limitation, we establish a timely warning system for septic shock with data-task engineering, a novel technique regarding the control of data samples and prediction targets. Leveraging machine learning techniques and the real-world electronic medical records from the MIMIC-IV (Medical Information Mart for Intensive Care) database, our system, TEW3S (Timely Early Warning System for Septic Shock), successfully predicted 94% of all shock events with one true alarm for every four false alarms and a maximum lead time of 8 hours. This approach emphasizes the often-overlooked importance of prediction timeliness and may provide a practical avenue to develop a timely warning system for acute deterioration in hospital settings, ultimately improving patient outcomes.

Critical illness myopathy (CIM) detrimentally affects muscle function in ICU patients, with a dramatic loss of muscle mass and function where the loss in specific force exceeds the loss in muscle mass (maximum force normalized to muscle cross-sectional area). The preferential loss of the molecular motor protein myosin, representing the hallmark of CIM, exhibiting a significant negative impact on the specific force generation by the muscle. Interestingly however, the preferential myosin loss is a relatively late event, and a specific loss in force generation capacity, is observed prior to the myosin loss. In the current study, employing an optimized cadmium telluride quantum dots (QD) mediated-thermometry approach to assess the efficiency of the myosin, we were able to determine the loss in specific force generated by the muscle, prior to the preferential loss of myosin. Reduction in QD fluorescent intensity correlates with greater heat loss, reflecting inefficient myosin function (less mechanical work performed and more heat loss on ATP hydrolysis by myosin). A significant decrease in myosin efficiency was observed in rats subjected to the ICU condition (immobilization and mechanical ventilation) for 5 days using an established experimental ICU model not limited by early mortality. Thus, qualitative myosin changes preceding quantitative myosin loss offer a mechanism underlying the early loss in specific force generation capacity associated with CIM and opens a venue for future CIM intervention strategies.