Document Detail


Maximal exercise and muscle oxygen extraction in acclimatizing lowlanders and high altitude natives.
MedLine Citation:
PMID:  16581864     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The tight relation between arterial oxygen content and maximum oxygen uptake (Vv(o2max)within a given person at sea level is diminished with altitude acclimatization. An explanation often suggested for this mismatch is impairment of the muscle O(2) extraction capacity with chronic hypoxia, and is the focus of the present study. We have studied six lowlanders during maximal exercise at sea level (SL) and with acute (AH) exposure to 4,100 m altitude, and again after 2 (W2) and 8 weeks (W8) of altitude sojourn, where also eight high altitude native (Nat) Aymaras were studied. Fractional arterial muscle O(2) extraction at maximal exercise was 90.0+/-1.0% in the Danish lowlanders at sea level, and remained close to this value in all situations. In contrast to this, fractional arterial O(2) extraction was 83.2+/-2.8% in the high altitude natives, and did not change with the induction of normoxia. The capillary oxygen conductance of the lower extremity, a measure of oxygen diffusing capacity, was decreased in the Danish lowlanders after 8 weeks of acclimatization, but was still higher than the value obtained from the high altitude natives. The values were (in ml min(-1) mmHg(-1)) 55.2+/-3.7 (SL), 48.0+/-1.7 (W2), 37.8+/-0.4 (W8) and 27.7+/-1.5 (Nat). However, when correcting oxygen conductance for the observed reduction in maximal leg blood flow with acclimatization the effect diminished. When calculating a hypothetical leg V(o2max)at altitude using either the leg blood flow or the O(2) conductance values obtained at sea level, the former values were almost completely restored to sea level values. This would suggest that the major determinant V(o2max)for not to increase with acclimatization is the observed reduction in maximal leg blood flow and O(2) conductance.
Authors:
Carsten Lundby; Mikael Sander; Gerrit van Hall; Bengt Saltin; José A L Calbet
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2006-03-31
Journal Detail:
Title:  The Journal of physiology     Volume:  573     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-06-05     Completed Date:  2006-07-27     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  535-47     Citation Subset:  IM    
Affiliation:
Copenhagen Muscle Center, Rigshospitalet section 7652, Blegdamsvej 9, 2100 Copenhagen O, Denmark. lundby@idraet.au.dk
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / physiology*
Adult
Altitude*
Exercise Test / methods
Humans
Male
Muscle, Skeletal / physiology*
Oxygen Consumption / physiology*
Physical Exertion / physiology*
Comments/Corrections

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