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

Daryl P. Wilkerson, Nicolas Berger, Andrew M. Jones

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    The purpose of this study was to examine the influence of hyperoxic gas (50% O2 in N2) inspiration on pulmonary oxygen uptake (over(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 over(V, ̇)O2 peak) and supra-maximal (105% over(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 over(V, ̇)O2 time constant during moderate (N: 28 ± 3 s versus H: 31 ± 7 s), severe (N: 32 ± 9 s versus H: 33 ± 6 s) or supra-maximal (N: 37 ± 9 s versus H: 37 ± 9 s) exercise. Hyperoxia resulted in a 45% reduction in the amplitude of the over(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 over(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.

    Original languageEnglish
    Pages (from-to)92-106
    Number of pages15
    JournalRespiratory Physiology and Neurobiology
    Issue number1
    Publication statusPublished - 1 Aug 2006


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