| Cardiorespiratory dynamics to hypoxia at the onset of cycling exercise in male endurance subjects. | |
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MedLine Citation:
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PMID: 16208284 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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AIM: It is well established that altering O2 delivering to contracting skeletal muscle affects human performance. In this respect, a reduced O2 supply (e.g., hypoxia) increases the rate of muscle fatigue. This study aimed to determine the effects of moderate hypoxia and exercise intensity on oxygen uptake (VO2) and cardiac output (CO) kinetics during moderate [below the ventilatory threshold (VT)] and heavy (above VT) constant work rate cycling exercises. METHODS: Eight trained males (age, mean+/-SD, 22+/-3 years; height 182+/-5 cm; body mass 71+/-12 kg) performed at the same relative intensity in normoxic (FIO2=0.21) and hypoxic (FIO2=0.13) conditions moderate and heavy exercises during which pulmonary gas exchange was determined breath-by-breath and CO was monitored beat-by-beat with Doppler echocardiography. RESULTS: The rate of increase (t63%, corresponding to time constant and time delay of a monoexponential response) in CO was significantly faster than that of VO2 in 3 out of 4 experimental conditions (p<0.05). Moreover VO2 kinetics were significantly slowed by hypoxia and speeded by exercise intensity, while CO responses were unaffected by such conditions. A slowed CO response was apparent in hypoxia compared to normoxia (p>0.05) in heavy exercise. CONCLUSIONS: These results suggest an absence of coupling between CO and VO2 kinetics, and that cardiorespiratory O2 delivery is likely different at exercise onset as a function of exercise intensity and FIO2. |
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Authors:
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S Perrey; C Cleuziou; A M Lecoq; D Courteix; P Obert |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of sports medicine and physical fitness Volume: 45 ISSN: 0022-4707 ISO Abbreviation: J Sports Med Phys Fitness Publication Date: 2005 Mar |
Date Detail:
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Created Date: 2005-10-06 Completed Date: 2006-10-13 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0376337 Medline TA: J Sports Med Phys Fitness Country: Italy |
Other Details:
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Languages: eng Pagination: 7-12 Citation Subset: IM |
Affiliation:
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Laboratoire Efficience et Déficience Motrices EA 2991, Montpellier, France. stephane.perrey@univ-montp1.fr |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anaerobic Threshold / physiology Analysis of Variance Anoxia / physiopathology* Bicycling / physiology* Cardiac Output Echocardiography, Doppler Humans Least-Squares Analysis Male Muscle Fatigue / physiology Oxygen Consumption / physiology* Physical Endurance / physiology* Pulmonary Gas Exchange / physiology |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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