Please use this identifier to cite or link to this item:
|Title:||Effect of acute severe hypoxia on peripheral fatigue and endurance capacity in healthy humans|
|Keywords:||Severe hypoxia;Limb locomotor muscles|
|Citation:||American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 292:1, pp. R598 - R606, 2007|
|Abstract:||We hypothesized that severe hypoxia limits exercise performance via decreased contractility of limb locomotor muscles. Nine male subjects [mean ± SE maximum O2 uptake (V̇o2 max) = 56.5 ± 2.7 ml·kg−1·min−1] cycled at ≥90% V̇o2 max to exhaustion in normoxia [NORM-EXH; inspired O2 fraction (FiO2) = 0.21, arterial O2 saturation (SpO2) = 93 ± 1%] and hypoxia (HYPOX-EXH; FiO2 = 0.13, SpO2 = 76 ± 1%). The subjects also exercised in normoxia for a time equal to that achieved in hypoxia (NORM-CTRL; SpO2 = 96 ± 1%). Quadriceps twitch force, in response to supramaximal single (nonpotentiated and potentiated 1 Hz) and paired magnetic stimuli of the femoral nerve (10–100 Hz), was assessed pre- and at 2.5, 35, and 70 min postexercise. Hypoxia exacerbated exercise-induced peripheral fatigue, as evidenced by a greater decrease in potentiated twitch force in HYPOX-EXH vs. NORM-CTRL (−39 ± 4 vs. −24 ± 3%, P < 0.01). Time to exhaustion was reduced by more than two-thirds in HYPOX-EXH vs. NORM-EXH (4.2 ± 0.5 vs. 13.4 ± 0.8 min, P < 0.01); however, peripheral fatigue was not different in HYPOX-EXH vs. NORM-EXH (−34 ± 4 vs. −39 ± 4%, P > 0.05). Blood lactate concentration and perceptions of limb discomfort were higher throughout HYPOX-EXH vs. NORM-CTRL but were not different at end-exercise in HYPOX-EXH vs. NORM-EXH. We conclude that severe hypoxia exacerbates peripheral fatigue of limb locomotor muscles and that this effect may contribute, in part, to the early termination of exercise.|
|Appears in Collections:||Sport|
Dept of Life Sciences Research Papers
Items in BURA are protected by copyright, with all rights reserved, unless otherwise indicated.