Document Detail

Oxygen uptake response during maximal cycling in hyperoxia, normoxia and hypoxia.
MedLine Citation:
PMID:  11601554     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Oxygen uptake (VO2) on-kinetics is decelerated in acute hypoxia and accelerated in hyperoxia in comparison with normoxia during submaximal exercise. However, the effects of fraction of oxygen in inspired air (FIO2) on VO2 kinetics during maximal exercise are unknown. HYPOTHESIS: The effects of FIO2 on VO2 on-kinetics during maximal exercise are similar to submaximal exercise. METHODS: There were 11 endurance athletes who were studied during maximal 7-min cycle ergometer exercise in hyperoxia (FIO2 0.325), hypoxia (FIO2 0.166) and normoxia (FIO2 0.209). The individual VO2 data were fit to a curve by using a three exponential model. RESULTS: In hypoxia, VO2 on-response amplitude during Phase 2 (approximately 20-100 s from the beginning of exercise) was lower (p < 0.05) when compared with hyperoxia; time constant of VO2 Phase 3 (beyond approximately 100 s after beginning of exercise) was shorter (p < 0.05) when compared with hyperoxia; and mean response time (MRT, O-63%) for VO2peak was shorter (p < 0.05) when compared with normoxia and hyperoxia. VO2peak was higher in hyperoxia (4.80 +/- 0.48 L x min(-1), p < 0.05) and lower in hypoxia (4.03 +/- 0.46 L x min(-1), p < 0.05) than in normoxia (4.36 +/- 0.44 L x min(-1)). CONCLUSIONS: Moderate hypoxia or hyperoxia do not affect VO2 time constants at the onset of maximal exercise. However, MRT for VO2peak is shortened in hypoxia. It is suggested that the differences in VO2peak and power output during the latter half of the test and the point that FIO2 was modified only moderately might explain most of the discrepancy with the previous studies.
J E Peltonen; H O Tikkanen; J J Ritola; M Ahotupa; H K Rusko
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  72     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2001-10-16     Completed Date:  2002-01-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  904-11     Citation Subset:  IM; S    
Unit for Sports and Exercise Medicine, Institute of Clinical Medicine, University of Helsinki, Finland.
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MeSH Terms
Anoxia / physiopathology*
Exercise / physiology*
Exercise Test
Heart Rate
Hyperoxia / physiopathology*
Oxidative Stress / physiology
Oxygen Consumption*

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