Acute Physiological Responses To Moderate-Load Resistance Exercise In Hypoxia

This study assessed whether hypoxia augments anabolic responses to moderate-load resistance exercise. Fourteen trained males performed moderate-load resistance exercise in normoxia (NORM; fraction of inspired oxygen [FIO2] = 21%) and moderate-level hypoxia (MH; FIO2 = 16%). Exercise comprised 3 sets of 10 repetitions of squats and deadlifts at 60% of 1-repetition maximum, with 60 s inter-set rest. Blood lactate (BLa-) was quantified after each exercise, while arterial oxygen saturation (SpO2) and heart rate (HR) were assessed following each set. Thigh circumference was measured before and following exercise. Muscle activation and oxygenation were monitored via surface electromyography (EMG) and near infrared spectroscopy, respectively. Relative BLa- concentrations were significantly higher following squats (p = 0.041) and deadlifts (p = 0.002) in MH than NORM. SpO2 was lower following each set in MH compared with NORM (p < 0.001), though HR and thigh circumference were not different between conditions. Integrated EMG was higher in MH than in NORM for the squat during several repetitions (p ≤ 0.032). Measures of muscle oxygen status were not significantly different between conditions (p ≥ 0.247). The main findings from this study suggest that hypoxia during moderate-load resistance exercise augments metabolite accumulation and muscle activation. However, a significant hypoxic dose was not measured at the muscle, possibly because of the moderate level of hypoxia employed. The current data supports previous hypotheses that have suggested hypoxia can augment some physiological responses that are important for muscular development, and may therefore provide benefit over the equivalent training in normoxia