High-Altitude Acclimatization Improves Recovery from Muscle Fatigue

摘要

Purpose We investigated the effect of high-altitude acclimatization on peripheral fatigue compared with sea level and acute hypoxia. Methods At sea level (350 m), acute hypoxia (environmental chamber), and chronic hypoxia (5050 m, 5-9 d) (partial pressure of inspired oxygen = 140, 74 and 76 mm Hg, respectively), 12 participants (11 in chronic hypoxia) had the quadriceps of their dominant leg fatigued by three bouts of 75 intermittent electrically evoked contractions (12 pulses at 15 Hz, 1.6 s between train onsets, and 15 s between bouts). The initial peak force was 30% of maximal voluntary force. Recovery was assessed by single trains at 1, 2, and 3 min postprotocol. Tissue oxygenation of rectus femoris was recorded by near-infrared spectroscopy. Results At the end of the fatigue protocol, the impairments of peak force and peak rates of force development and relaxation were greater (all P 0.05). Conclusions Muscle adaptations occurring with chronic hypoxia, independent of other adaptations, positively influence muscle contractility during and after repeated contractions at high altitude.