Influence of hyperoxia on pulmonary O 2 uptake kinetics following the onset of exercise in humans
The purpose of this study was to examine the influence of hyperoxic gas (50% O 2 in N 2) inspiration on pulmonary oxygen uptake ( V ˙ O 2 ) kinetics during step transitions to moderate, severe and supra-maximal intensity cycle exercise. Seven healthy male subjects completed repeat transitions to mod...
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Published in | Respiratory physiology & neurobiology Vol. 153; no. 1; pp. 92 - 106 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
01.08.2006
|
Subjects | |
Online Access | Get full text |
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Summary: | The purpose of this study was to examine the influence of hyperoxic gas (50% O
2 in N
2) inspiration on pulmonary oxygen uptake (
V
˙
O
2
) 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
˙
O
2
peak) and supra-maximal (105%
V
˙
O
2
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
˙
O
2
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
V
˙
O
2
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
˙
O
2
kinetics are not normally constrained by (diffusional) O
2 transport limitations during moderate, severe or supra-maximal intensity exercise in young healthy subjects performing upright cycle exercise. |
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ISSN: | 1569-9048 1878-1519 |
DOI: | 10.1016/j.resp.2005.09.006 |