Document Detail


Comparison of hyperthermic hyperventilation during passive heating and prolonged light and moderate exercise in the heat.
MedLine Citation:
PMID:  22923504     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Elevation of core temperature leads to increases in ventilation in both resting subjects and those engaged in prolonged exercise. We compared the characteristics of the hyperthermic hyperventilation elicited during passive heating at rest and during prolonged moderate and light exercise. Twelve healthy men performed three trials: a rest trial in which subjects were passively heated using hot-water immersion (41°C) and a water-perfused suit and two exercise trials in which subjects exercised at 25% (light) or 50% (moderate) of peak oxygen uptake in the heat (37°C and 50% relative humidity) after first using water immersion (18°C) to reduce resting esophageal temperature (T(es)). This protocol enabled detection of a T(es) threshold for hyperventilation during the exercise. When minute ventilation (Ve) was expressed as a function of T(es), 9 of the 12 subjects showed T(es) thresholds for hyperventilation in all trials. The T(es) thresholds for increases in Ve during light and moderate exercise (37.1 ± 0.4 and 36.9 ± 0.4°C) were both significantly lower than during rest (38.3 ± 0.6°C), but the T(es) thresholds did not differ between the two exercise intensities. The sensitivity of Ve to increasing T(es) (slope of the T(es)-Ve relation) above the threshold was significantly lower during moderate exercise (8.7 ± 3.5 l · min(-1) · °C(-1)) than during rest (32.5 ± 24.2 l · min(-1) · °C(-1)), but the sensitivity did not differ between light (10.4 ± 13.0 l · min(-1) · °C(-1)) and moderate exercise. These results suggest the core temperature threshold for hyperthermic hyperventilation and the hyperventilatory response to increasing core temperature in passively heated subjects differs from that in exercising subjects, irrespective of whether the exercise is moderate or light.
Authors:
Bun Tsuji; Yasushi Honda; Naoto Fujii; Narihiko Kondo; Takeshi Nishiyasu
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-08-23
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-05     Completed Date:  2013-04-12     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:  1388-97     Citation Subset:  IM    
Affiliation:
Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
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MeSH Terms
Descriptor/Qualifier:
Adult
Body Temperature Regulation / physiology
Exercise / physiology*
Fever / complications*,  physiopathology*
Hot Temperature / adverse effects*
Humans
Hyperventilation / etiology*,  physiopathology*
Male
Models, Biological
Respiratory Physiological Phenomena
Skin Temperature / physiology
Young Adult

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


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