Document Detail


Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans.
MedLine Citation:
PMID:  21088208     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We examined whether less convective heat loss during exercise at high altitude than at sea level was partially caused by reduced cutaneous vasodilation due to enhanced plasma water loss into contracting muscles and whether it was caused by hypoxia rather than by hypobaria. Seven young men performed cycling exercise for 40 min at 50% peak aerobic power in normoxia at (710 mmHg) 610 m, determined before the experiments, in three trials: 1) normobaric normoxia at 610 m (CNT), 2) hypobaric hypoxia [low pressure and low oxygen (LPLO)] at 3,200 m (510 mmHg), 3) normobaric hypoxia [normal pressure and low oxygen (NPLO)] at 610 m, in an artificial climate chamber where atmospheric temperature and relative humidity were maintained at 30°C and 50%, respectively. Subjects in CNT and LPLO breathed room air, whereas those in NPLO breathed a mixed gas of 14% O₂ balanced N₂, equivalent to the gas composition in LPLO. We measured change in PV (ΔPV), oxygen consumption rate (Vo₂), mean arterial blood pressure (MBP), esophageal temperature (T(es)), mean skin temperature (T(sk)), forearm skin blood flow (FBF), and sweat rate (SR) during exercise. Although Vo₂, MBP, T(sk), and SR responses during exercise were similar between trials (P > 0.05), the sensitivity of forearm vascular conductance (FBF/MBP) in response to increased T(es) was lower in LPLO and NPLO than in CNT (P < 0.05), whereas that of SR was not, resulting in a greater increase in T(es) from minute 5 to 40 of exercise in LPLO and NPLO than in CNT (P = 0.026 and P = 0.011, respectively). ΔPV during exercise was twofold greater in LPLO and NPLO than in CNT. These variables were not significantly different between LPLO and NPLO. Thus reduced convective heat loss during exercise at 3,200 m was partially caused by reduced cutaneous vasodilation due to enhanced PV loss. Moreover, this may be caused by hypoxia rather than by hypobaria.
Authors:
Ken Miyagawa; Yoshi-Ichiro Kamijo; Shigeki Ikegawa; Masaki Goto; Hiroshi Nose
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-11-18
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  110     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-13     Completed Date:  2011-08-02     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:  157-65     Citation Subset:  IM    
Affiliation:
Department of Sports Medical Sciences, Institute on Aging and Adaptation, Shinshu University Graduate School, Matsumoto, Japan.
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MeSH Terms
Descriptor/Qualifier:
Adult
Altitude*
Body Temperature Regulation / physiology*
Exercise / physiology*
Humans
Hyperthermia, Induced
Male
Oxygen Consumption / physiology
Physical Exertion / physiology*
Skin Physiological Phenomena*
Vasodilation / physiology*
Water
Water Loss, Insensible / physiology*
Chemical
Reg. No./Substance:
7732-18-5/Water

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


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