Document Detail


Improved VO2 uptake kinetics and shift in muscle fiber type in high-altitude trekkers.
MedLine Citation:
PMID:  21868681     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The study investigated the effect of prolonged hypoxia on central [i.e., cardiovascular oxygen delivery (Q(a)O(2))] and peripheral (i.e., O(2) utilization) determinants of oxidative metabolism response during exercise in humans. To this aim, seven male mountaineers were examined before and immediately after the Himalayan Expedition Interamnia 8000-Manaslu 2008, lasting 43 days, among which, 23 days were above 5,000 m. The subjects showed a decrease in body weight (P < 0.05) and of power output during a Wingate Anaerobic test (P < 0.05) and an increase of thigh cross-sectional area (P < 0.05). Absolute maximal O(2) uptake (VO(2max)) did not change. The mean response time of VO(2) kinetics at the onset of step submaximal cycling exercise was reduced significantly from 53.8 s ± 10.9 to 39.8 s ± 10.9 (P < 0.05), whereas that of Q(a)O(2) was not. Analysis of single fibers dissected from vastus lateralis biopsies revealed that the expression of slow isoforms of both heavy and light myosin subunits increased, whereas that of fast isoforms decreased. Unloaded shortening velocity of fibers was decreased significantly. In summary, independent findings converge in indicating that adaptation to chronic hypoxia brings about a fast-to-slow transition of muscle fibers, resulting in a faster activation of the mitochondrial oxidative metabolism. These results indicate that a prolonged and active sojourn in hypoxia may induce muscular ultrastructural and functional changes similar to those observed after aerobic training.
Authors:
C Doria; L Toniolo; V Verratti; P Cancellara; T Pietrangelo; V Marconi; A Paoli; S Pogliaghi; G Fanò; C Reggiani; C Capelli
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-08-25
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  111     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-14     Completed Date:  2012-04-30     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1597-605     Citation Subset:  IM    
Affiliation:
Department of Neurosciences and Imaging, University of Chieti-Pescara, Chieti, Italy.
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / physiology
Adult
Altitude*
Anoxia / physiopathology
Biomechanics
Exercise / physiology*
Humans
Kinetics
Male
Middle Aged
Mitochondria, Muscle / physiology
Mountaineering / physiology*
Muscle Fibers, Skeletal / classification,  physiology*
Myosins / physiology
Oxygen Consumption / physiology*
Chemical
Reg. No./Substance:
EC 3.6.4.1/Myosins

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


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