Document Detail

Effects of exercise in the heat on thermoregulation of Japanese and Malaysian males.
MedLine Citation:
PMID:  16079566     Owner:  NLM     Status:  MEDLINE    
The effect of low-intensity exercise in the heat on thermoregulation and certain biochemical changes in temperate and tropical subjects under poorly and well-hydrated states was examined. Two VO2max matched groups of subjects consisting of 8 Japanese (JS) and 8 Malaysians (MS) participated in this study under two conditions: poorly-hydrated (no water was given) and well-hydrated (3 mL x Kg(-1) body weight of water was provided at onset of exercise, and the 15th, 35th and 55th min of exercise). The experimental room in both countries was adjusted to a constant level (Ta: 31.6+/-0.03 degrees C, rh: 72.3+/-0.13%). Subjects spent an initial 10 min rest, 60 min of cycling at 40% VO2max and then 40 min recovery in the experimental room. Rectal temperatures (Tre) skin temperatures (Tsk), heart rate (HR), heat-activated sweat glands density (HASG), local sweat rate (M sw-back) and percent dehydration were recorded during the test. Blood samples were analysed for plasma glucose and lactate levels.The extent of dehydration was significantly higher in the combined groups of JS (1.43+/-0.08%) compared to MS (1.15+/-0.05%). During exercise M sw-back was significantly higher in JS compared to MS in the well-hydrated condition. The HASG was significantly more in JS compared to MS at rest and recovery. Tre was higher in MS during the test. Tsk was significantly higher starting at the 5th min of exercise until the end of the recovery period in MS compared to JS. In conclusion, tropical natives have lower M sw-back associated with higher Tsk and Tre during the rest, exercise and recovery periods. However, temperate natives have higher M sw-back and lower Tsk and Tre during experiments in a hot environment. This phenomenon occurs in both poorly-hydrated and well-hydrated states with low intensity exercise. The differences in M sw-back, Tsk and Tre are probably due to a setting of the core temperature at a higher level and enhancement of dry heat loss, which occurred during passive heat exposure.
Mohamed Saat; Yutaka Tochihara; Nobuko Hashiguchi; Roland Gamini Sirisinghe; Mizuho Fujita; Chin Mei Chou
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of physiological anthropology and applied human science     Volume:  24     ISSN:  1345-3475     ISO Abbreviation:  J Physiol Anthropol Appl Human Sci     Publication Date:  2005 Jul 
Date Detail:
Created Date:  2005-08-04     Completed Date:  2005-10-20     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  100930389     Medline TA:  J Physiol Anthropol Appl Human Sci     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  267-75     Citation Subset:  IM    
Department of Ergonomics, Faculty of Design, Kyushu University.
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MeSH Terms
Adaptation, Physiological / physiology*
Analysis of Variance
Blood Glucose
Body Temperature
Body Temperature Regulation / physiology*
Dehydration / ethnology,  physiopathology*
Exercise / physiology*
Heart Rate
Hot Temperature*
Lactic Acid / blood
Sweating / physiology
Reg. No./Substance:
0/Blood Glucose; 50-21-5/Lactic Acid

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