Influence of hyperoxia on pulmonary O2 uptake kinetics following the onset of exercise in humans

Respir Physiol Neurobiol. 2006 Aug;153(1):92-106. doi: 10.1016/j.resp.2005.09.006. Epub 2005 Nov 22.


The purpose of this study was to examine the influence of hyperoxic gas (50% O2 in N2) inspiration on pulmonary oxygen uptake (V(O2)) kinetics during step transitions to moderate, severe and supra-maximal intensity cycle exercise. Seven healthy male subjects completed repeat transitions to moderate (90% of the gas exchange threshold, GET), severe (70% of the difference between the GET and V(O2) peak) and supra-maximal (105% V(O2) peak) intensity work rates while breathing either normoxic (N) or hyperoxic (H) gas before and during exercise. Hyperoxia had no significant effect on the Phase II V(O2) time constant during moderate (N: 28+/-3s versus H: 31+/-7s), severe (N: 32+/-9s versus H: 33+/-6s) or supra-maximal (N: 37+/-9s versus H: 37+/-9s) exercise. Hyperoxia resulted in a 45% reduction in the amplitude of the V(O2) slow component during severe exercise (N: 0.60+/-0.21 L min(-1) versus H: 0.33+/-0.17 L min(-1); P < 0.05) and a 15% extension of time to exhaustion during supra-maximal exercise (N: 173+/-28 s versus H: 198+/-41 s; P < 0.05). These results indicate that the Phase II V(O2) kinetics are not normally constrained by (diffusional) O2 transport limitations during moderate, severe or supra-maximal intensity exercise in young healthy subjects performing upright cycle exercise.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adult
  • Exercise / physiology*
  • Exercise Test / methods
  • Humans
  • Hyperoxia / physiopathology
  • Hyperoxia / rehabilitation*
  • Inhalation / physiology*
  • Male
  • Oxygen Consumption / physiology*
  • Pulmonary Gas Exchange / physiology
  • Time Factors