Hyperoxia significantly increased the maximum number of repetitions during a low-intensity single-joint repetitive muscle contraction task compared to normoxia (132 vs 114 repetitions, P < 0.001).
RCT (n=25)
Single-blind
Counterbalanced
No
Does mild hyperoxia improve dynamic muscular endurance during low-intensity repetitive exercise in healthy young men?
Mild hyperoxia (FiO2 = 0.30) acutely enhances dynamic muscular endurance during low-intensity repetitive exercise, with the magnitude of benefit correlating with individual whole-body endurance capacity (VO2max).
Absolute Event Rate: 132% vs 114%
p-value: p=<0.001
Low-intensity training involving high repetitions is recommended to enhance muscular endurance. Hyperoxic conditions could increase the number of repetitions until exhaustion and thereby improve the results of muscular endurance training. This study aimed to investigate the acute effects of hyperoxia on dynamic muscular endurance, and determine individual factors that may be related to these effects. A single-blinded, counterbalanced crossover design was used. Twenty-five young men performed repetitions of the one-arm preacher curl at 30% of their 1-repetition maximum until exhaustion under hyperoxic and normoxic conditions. The maximum number of repetitions was recorded as an index of muscular endurance. Electromyogram (EMG) and near-infrared spectroscopy parameters were measured in the biceps brachii. The maximum number of repetitions was greater (P < 0.001) under hyperoxic conditions (132 ± 59 repetitions) than under normoxic conditions (114 ± 40 repetitions). The root mean square amplitude of EMG and oxygenated hemoglobin concentration for the last five repetitions under normoxic conditions were greater than those under hyperoxic conditions (P = 0.015 and P = 0.003, respectively). The percent change in the maximum number of repetitions between hyperoxic and normoxic conditions had significant positive correlations with individual maximal oxygen uptake measured using an incremental cycle ergometer test (r = 0.562, 95% confidence intervals CI = 0.213-0.783, P = 0.003), but not with muscle strength (τ = -0.124, 95% CI = -0.424-0.170, P = 0.387). The 95% CI for the correlation coefficient between the percent change in the maximum number of repetitions and muscular endurance included 0 (τ = 0.284, 95% CI = -0.003-0.565, P = 0.047); this indicated no significant correlation between the two parameters. The results suggest that hyperoxia can acutely enhance dynamic muscular endurance, with delayed elevation of EMG amplitude due to fatigue, and the effects are associated with individual whole-body endurance capacity.
Kojima et al. (Tue,) conducted a rct in Healthy (n=25). Hyperoxia vs. Normoxia (FiO2 = 0.21) was evaluated on Maximum number of repetitions of one-arm preacher curl at 30% 1-RM until exhaustion (p=<0.001). Hyperoxia significantly increased the maximum number of repetitions during a low-intensity single-joint repetitive muscle contraction task compared to normoxia (132 vs 114 repetitions, P < 0.001).
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