Macdonald M, Pedersen P K, Hughson R L
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
J Appl Physiol (1985). 1997 Oct;83(4):1318-25. doi: 10.1152/jappl.1997.83.4.1318.
We examined the hypothesis that O2 uptake (VO2) would change more rapidly at the onset of step work rate transitions in exercise with hyperoxic gas breathing and after prior high-intensity exercise. The kinetics of VO2 were determined from the mean response time (MRT; time to 63% of total change in VO2) and calculations of O2 deficit and slow component during normoxic and hyperoxic gas breathing in one group of seven subjects during exercise below and above ventilatory threshold (VT) and in another group of seven subjects during exercise above VT with and without prior high-intensity exercise. In exercise transitions below VT, hyperoxic gas breathing did not affect the kinetic response of VO2 at the onset or end of exercise. At work rates above VT, hyperoxic gas breathing accelerated both the on- and off-transient MRT, reduced the O2 deficit, and decreased the VO2 slow component from minute 3 to minute 6 of exercise, compared with normoxia. Prior exercise above VT accelerated the on-transient MRT and reduced the VO2 slow component from minute 3 to minute 6 of exercise in a second bout of exercise with both normoxic and hyperoxic gas breathing. However, the summated O2 deficit in the second normoxic and hyperoxic steps was not different from that of the first steps in the same gas condition. Faster on-transient responses in exercise above, but not below, VT with hyperoxia and, to a lesser degree, after prior high-intensity exercise above VT support the theory of an O2 transport limitation at the onset of exercise for workloads >VT.
在高氧气体呼吸的运动中以及在先前进行高强度运动后，氧摄取量（VO₂）在运动中步幅功率转换开始时的变化会更快。在一组七名受试者低于和高于通气阈值（VT）进行运动期间以及另一组七名受试者在有和没有先前高强度运动的情况下高于VT进行运动期间，通过平均反应时间（MRT；达到VO₂总变化的63%所需的时间）以及在常氧和高氧气体呼吸期间对氧亏缺和慢成分的计算来确定VO₂的动力学。在低于VT的运动转换中，高氧气体呼吸不影响运动开始或结束时VO₂的动力学反应。与常氧相比，在高于VT的功率下，高氧气体呼吸加速了运动开始和结束时的瞬态MRT，减少了氧亏缺，并在运动的第3分钟至第6分钟减少了VO₂慢成分。在第二次常氧和高氧气体呼吸的运动中，先前高于VT的运动加速了运动开始时的瞬态MRT，并在运动的第3分钟至第6分钟减少了VO₂慢成分。然而，第二次常氧和高氧步骤中的累积氧亏缺与相同气体条件下的第一步没有差异。在高于VT（而非低于VT）的运动中，高氧以及在较小程度上先前高于VT的高强度运动后更快的运动开始时瞬态反应支持了这样一种理论，即对于工作量>VT的运动开始时存在氧运输限制。
