Effects of Hypoxia-Hyperoxia Preconditioning on Indicators of Muscle Damage After Acute Resistance Exercise in Male Athletes.

Purpose: The purpose of this study was to investigate the effects of acute repeated hypoxia-hyperoxia preconditioning on resistance exercise (RE)-induced muscle damage in male athletes. Methods: Eleven young male athletes participated in this randomized double-blind counter-balanced crossover study, and were divided into Normoxia (N) and Hypoxia-Hyperoxia (HH) trials. Subjects of the respective trials were supplied with normoxic (FiO2 = 0.21), or alternating hypoxic/hyperoxic air (FiO2 = 0.10/0.99, 5 min each) for 60 min. Thirty minutes after preconditioning, subjects performed acute bouts of RE consisting of bench press, deadlift, and squats. Each exercise included 6 sets of 10 repetitions at 75% one-repetition maximum (1RM) with 2 min rest between sets. After a 2-week washout period, subjects changed trials and completed the same study procedure after the alternate preconditioning. Muscle soreness, maximal voluntary contraction (MVC), and circulating biochemical markers were tested before preconditioning (baseline) and during recovery at 0, 24, and 48 h after exercise. Results: Acute RE significantly increased levels of muscle soreness, creatine kinase (CK) and myoglobin (Mb), and decreased levels of peak knee extension torque in the N trial. Muscle soreness, CK, and Mb levels of the HH trial were significantly lower than that of the N trial after exercise. Interestingly, interleukin-6 (IL-6) levels of the HH trial increased significantly 0 h after exercise compared to baseline and were significantly higher than that of the N trial 0 and 24 h after exercise. However, no significant differences of thiobarbituric acid reactive substances (TBARS), cortisol, testosterone, peak torque, and average power levels were found between N and HH trials during recovery. Conclusion: Our data suggest that pre-exercise treatment of alternating hypoxic/hyperoxic air could attenuate muscle damage and pain after acute RE, but has no effect on muscle strength recovery in young male athletes.

Night time resistance exercise alters muscular IL-6-related protein signaling, but not muscle growth after 10 weeks of resistance training in male rats.

The present study investigated the time-of-day effects on acute response and chronic adaptations to resistance exercise (RE) in rat skeletal muscle. Male rats were divided into Early and Late training groups and performed climbing RE during the first or last hour of the active (dark) period, respectively. The first experiment measured muscle mass and strength after a 10-week climbing training program. The second experiment examined inflammatory signaling response and satellite cell (SC) numbers following an acute bout of RE. The results showed no significant differences between rats training at early and late active periods in relative muscle weight (muscle-to-weight ratio), cross sectional area (CSA) and strength. The acute study observed increased STAT1 phosphorylation, oxidative stress (2-thiobarbituric acid reacting substances, TBARS), SCs (Pax7+), neutrophils (His48+) and macrophages (CD68+), and decreased interleukin 6 (IL-6) protein expression of skeletal muscle relative to non-exercise control after an acute bout of RE. Interestingly, higher plasma IL-6 and STAT3 phosphorylation response was observed in the late training group when compared to the early training group after an acute bout of RE. The results of this study suggest that animals can adapt to resistance training at different time-of-day, by modulating inflammatory signaling of skeletal muscle.

Low Second-To-Fourth Digit Ratio Has High Explosive Power? A Prepubertal Study.

Hsu, CC, Fong, TH, Chang, HM, Su, B, Chi, CP, Kan, NW, and Hsu, MC. Low second-to-fourth digit ratio has high explosive power? A prepubertal study. J Strength Cond Res 32(7): 2091-2095, 2018-A recent study reported that lower limb explosive power had no correlation with the index finger: ring finger (2D:4D) ratio. However, many studies hypothesized that a lower 2D:4D ratio (reflecting a relative higher testosterone exposure) predicts higher physical fitness. The aim of this study was to replicate the study of explosive power and the 2D:4D ratio in a sample of Taiwanese children. A total of 541 Taiwanese prepubertal children (257 girls and 284 boys aged 9-10 years) participated in this study. This study analyzed the relationship between the 2D:4D ratio and explosive power. Explosive power of the lower limbs was assessed using the standing long jump (SLJ) test. The lengths of the second and fourth fingers of the right hand were measured to calculate the 2D:4D ratio. The SLJ length was correlated with the 2D:4D ratios (r = -0.144, p = 0.015) in boys. After controlling for age and the body mass index, this correlation remained significant (r = -0.134, p = 0.024). For girls, 2D:4D ratios were not significantly correlated with SLJ scores. These results indicate that the SLJ distance was negatively correlated with the 2D:4D ratio in boys, but not in girls. These findings might suggest that prenatal testosterone exposure is negatively correlated with the explosive power in men, but not in women.

Association Between Exercise Participation and Quality of Sleep and Life Among University Students in Taiwan.

This cross-sectional survey study examined exercise, sleep quality, and quality of life (QOL) in 1230 Taiwanese university students. Compared with women, men had higher body mass index (BMI) (22.3 ± 4.1 vs 20.7 ± 3.5 kg/m(2)), higher exercise frequency (2.6 ± 1.7 vs 2.0 ± 1.4 d/wk), better sleep quality (global Pittsburgh Sleep Quality Index 6.0 ± 2.8 vs 6.5 ± 2.7), better physical QOL (physical component summary 52.7 ± 6.2 vs 51.7 ± 6.6), and higher reporting of good self-perceived health (62.2% vs 43.3%) (P <01). However, gender differences were nonsignificant after multivariable adjustment. Exercise frequency, sleep quality, and QOL were significantly intercorrelated. After multivariable adjustment, self-perceived health and satisfaction with exercise participation predicted quality of sleep and QOL (P <01). Exercise frequency was positively correlated (P =012), and exercise intensity was negatively associated (P <001) with physical QOL. In conclusion, those who regularly exercised (at least 1 d/wk or 2.5 h/wk) had better QOL. Students with better self-perceived health or satisfaction with exercise participation also had better quality of sleep and better QOL.

Elite collegiate tennis athletes have lower 2D: 4D ratios than those of nonathlete controls.

The ratio of the length of the second finger (index finger) to the fourth finger (ring finger) (2D:4D ratio) is a putative marker for prenatal hormones. Physiological research has suggested a low 2D:4D ratio correlates with high athletic ability. Athletes of specific sports (e.g., American football) have lower 2D:4D ratios than those of nonathletes, whereas athletes of some sports (e.g., rowing, gymnastics, and soccer) do not. This study investigated the 2D:4D ratios among collegiate tennis athletes, elite collegiate tennis athletes, and nonelite collegiate tennis athletes and compared them with nonathletes of both sexes. The participants included 43 elite collegiate tennis athletes (Level I intercollegiate athletes in Taiwan; 27 males and 16 females), 107 nonelite collegiate tennis athletes (Level II athletes; 55 males and 52 females), and 166 nonathlete college students (80 males and 86 females). The principle findings suggest that (a) regardless of sex, collegiate tennis athletes have lower 2D:4D values than those of nonathletes; (b) elite collegiate tennis athletes have lower 2D:4D values than those of nonathletes; (c) among females but not males, athletes and nonelite athletes have lower 2D:4D values than those of nonathletes; and (d) males have lower 2D:4D values than those of females.