Document Detail

Oxygen transport during exercise at altitude and the lactate paradox: lessons from Operation Everest II and Pikes Peak.
MedLine Citation:
PMID:  1623889     Owner:  NLM     Status:  MEDLINE    
It seems unlikely that oxygen-limited metabolism explains the increased lactate concentrations in blood or muscle during exercise at high altitude compared with sea level values because: 1. Even marked hypoxia equivalent to that at the summit of Mt. Everest may not be sufficiently severe to impair function or to impair muscle oxidative metabolism markedly during exercise; 2. At this very high altitude, muscle hypoxemia is probably not the limiting factor for exercise performance; other systems, i.e., the cerebral cortex [24, 33], probably fail before hypoxemia impairs muscle metabolism; 3. The traditional view of oxygen-limited aerobic metabolism during exercise at high altitude does not explain a long-standing dilemma in altitude physiology, the lactate paradox (in which blood lactate accumulation during exercise is increased on arrival at high altitude but falls with acclimatization), because the lactate fall is independent of muscle oxygenation; 4. Net lactate release by the leg during exercise is independent of oxygenation; 5. Kinetic studies show that lactate appearance and disappearance are closely linked and both increase with acute altitude exposure and decrease with acclimatization; 6. Lactate appearance rate is strongly correlated with, and may be influenced by, the extent of beta-adrenergic stimulation; 7. The beta-adrenergic stimulation may be, in part, determined by the degree of arterial oxygenation.
J T Reeves; E E Wolfel; H J Green; R S Mazzeo; A J Young; J R Sutton; G A Brooks
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Exercise and sport sciences reviews     Volume:  20     ISSN:  0091-6331     ISO Abbreviation:  Exerc Sport Sci Rev     Publication Date:  1992  
Date Detail:
Created Date:  1992-08-07     Completed Date:  1992-08-07     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375434     Medline TA:  Exerc Sport Sci Rev     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  275-96     Citation Subset:  IM; S    
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MeSH Terms
Acclimatization / physiology
Atmosphere Exposure Chambers
Epinephrine / blood
Exercise / physiology*
Lactates / blood*
Muscles / metabolism
Oxygen / metabolism*
Oxygen Consumption / physiology
Grant Support
Reg. No./Substance:
0/Lactates; 51-43-4/Epinephrine; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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