Chapman R F, Emery M, Stager J M
Department of Kinesiology, Indiana University, Bloomington 47405, USA.
Respir Physiol. 1998 Jul;113(1):65-74. doi: 10.1016/s0034-5687(98)00043-7.
Increasing ventilation (VE) during hypoxic exercise may help to defend arterial O2 saturation (SaO2) and VO2max however, many athletes experience limitations to ventilatory flow and are not able to increase VE at high workrates. Five of 19 highly trained endurance athletes screened had < 5% of their tidal flow volume loop during maximal exercise meet the boundary set by their maximal resting flow volume loop. These five athletes were grouped as non-flow limited and compared to the five athletes who demonstrated the greatest percent of tidal volume flow limitation (56 +/- 11%) during maximal exercise (flow limited). Each athlete completed two incremental treadmill tests to exhaustion: normoxia and hypoxia (FI(O2) = 0.187). Non-flow limited athletes increased VE at VO2max from normoxia to hypoxia (140.9 +/- 13.4 vs. 154.7 +/- 11.9 L/min, P < 0.05), while flow limited athletes did not (159.5 +/- 9.4 vs. 162.3 +/- 6.0 L/min). The decline in SaO2 at VO2max from normoxia to hypoxia was not significantly different between groups. We conclude that athletes with little or no expiratory flow limitation are able to increase VE during maximal exercise in mild hypoxia, compared to athletes with significantly higher degrees of mechanical limitation. However this 'mechanical ventilatory reserve' does not appear to influence the ability to defend SaO2 or VO2max during maximal exercise in mild hypoxia.
在低氧运动期间增加通气量（VE）可能有助于维持动脉血氧饱和度（SaO2）和最大摄氧量（VO2max），然而，许多运动员存在通气流量限制，无法在高运动强度下增加VE。在19名经过高度训练的耐力运动员中，有5人在最大运动时，其潮气量流量环中只有不到5%符合其最大静息流量环设定的边界。这5名运动员被归类为非流量限制型，并与另外5名在最大运动时表现出最大潮气量流量限制百分比（56±11%）的运动员（流量限制型）进行比较。每位运动员完成两次递增式跑步机测试直至力竭：常氧和低氧（吸入氧分数（FI(O2)）=0.187）。非流量限制型运动员在从常氧到低氧的VO2max时增加了VE（140.9±13.4与154.7±11.9升/分钟，P<0.05），而流量限制型运动员则没有（159.5±9.4与162.3±6.0升/分钟）。两组在从常氧到低氧的VO2max时SaO2的下降没有显著差异。我们得出结论，与机械限制程度明显更高的运动员相比，呼气流量限制很小或没有的运动员在轻度低氧的最大运动期间能够增加VE。然而，这种“机械通气储备”似乎并不影响在轻度低氧的最大运动期间维持SaO2或VO2max的能力。
