Inspiratory muscle work in acute hypoxia influences locomotor muscle fatigue and exercise performance of healthy humans
Inspiratory muscle work in acute hypoxia influences locomotor muscle fatigue and exercise performance of healthy humans
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DOI：
10.1152/ajpregu.00442.2007
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发表时间：
2007-11-01
影响因子：
2.8
通讯作者：
Dempsey, Jerome A.
中科院分区：
文献类型：
--
作者：
Amann, Markus;Pegelow, David F.;Dempsey, Jerome A.
我们的目的是分离1）吸气肌功（W-b）和2）急性缺氧大强度运动期间动脉低氧血症对运动肌疲劳的独立影响。8名自行车运动员在低氧条件下[吸入氧分率（FIO 2）= 0.15，动脉血红蛋白饱和度（SaO（2））= 81 +/- 1%; 8.6 +/- 0.5 min，273 +/- 6 W;低氧对照组（Ctrl）]和在常氧条件下以相同的工作速率和持续时间（SaO（2）= 95 +/- 1%;常氧-对照）。重复这些试验，但通过比例辅助通气（PAV）实现Wb降低35 - 80%。在运动前和运动后2 min通过磁刺激股神经来评估股四头肌的抽搐力。通过比较相同SaO（2）水平下的低氧-对照组和低氧- PAV组，揭示了低氧条件下Wb对股四头肌疲劳的单独影响，与SaO（2）的降低无关（P = 0.10）。在低氧运动后，股四头肌的增强性肌颤力量（Q（tw，pot））立即降低了30 +/-3%，低于运动前的基线，而这种降低在PAV运动后减弱了约三分之一（21 +/-4%; P = 0.0007）. Wb对股四头肌疲劳的这种影响发生在运动工作率期间，在常氧下，降低Wb对疲劳没有显着影响。通过比较相同W-b水平下的低氧- PAV和常氧- PAV，揭示了SaO（2）降低对股四头肌疲劳的单独影响，与Wb的变化无关。在常氧- PAV后，Q（tw，pot）比运动前基线降低15 ± 2%，在低氧-PAV后，这种降低加剧了约三分之一（-22 ± 3%; P = 0.034）.我们的结论是，动脉低氧血症和W-B有助于显着的运动肌肉疲劳的发展速度在急性缺氧的运动过程中，这发生在工作率，在此期间，在常氧，W-B外周疲劳没有影响。
Our aim was to isolate the independent effects of 1) inspiratory muscle work ( W-b) and 2) arterial hypoxemia during heavy- intensity exercise in acute hypoxia on locomotor muscle fatigue. Eight cyclists exercised to exhaustion in hypoxia [ inspired O-2 fraction ( FIO2) = 0.15, arterial hemoglobin saturation ( SaO(2)) = 81 +/- 1%; 8.6 +/- 0.5 min, 273 +/- 6 W; Hypoxia- control ( Ctrl)] and at the same work rate and duration in normoxia ( SaO(2) = 95 +/- 1%; Normoxia- Ctrl). These trials were repeated, but with a 35 - 80% reduction in Wb achieved via proportional assist ventilation ( PAV). Quadriceps twitch force was assessed via magnetic femoral nerve stimulation before and 2 min after exercise. The isolated effects of Wb in hypoxia on quadriceps fatigue, independent of reductions in SaO(2), were revealed by comparing Hypoxia- Ctrl and Hypoxia- PAV at equal levels of SaO(2) ( P = 0.10). Immediately after hypoxic exercise potentiated twitch force of the quadriceps (Q(tw,pot)) decreased by 30 +/- 3% below preexercise baseline, and this reduction was attenuated by about one- third after PAV exercise ( 21 +/- 4%; P = 0.0007). This effect of Wb on quadriceps fatigue occurred at exercise work rates during which, in normoxia, reducing Wb had no significant effect on fatigue. The isolated effects of reduced SaO(2) on quadriceps fatigue, independent of changes in Wb, were revealed by comparing Hypoxia- PAV and Normoxia- PAV at equal levels of W-b. Q(tw,pot) decreased by 15 +/- 2% below preexercise baseline after Normoxia- PAV, and this reduction was exacerbated by about one- third after Hypoxia- PAV ( - 22 +/- 3%; P = 0.034). We conclude that both arterial hypoxemia and W-b contribute significantly to the rate of development of locomotor muscle fatigue during exercise in acute hypoxia; this occurs at work rates during which, in normoxia, W-b has no effect on peripheral fatigue.