| Exercise-rest cycles do not alter local and whole-body heat loss responses. | |
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MedLine Citation:
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PMID: 21270343 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Previous studies have suggested that greater core temperatures during intermittent exercise (Ex) are due to attenuated sweating (SR) and skin blood flow (SkBF) responses. We evaluated the hypothesis that heat loss is not altered during exercise-rest cycles (ER). Ten male participants randomly performed four 120min trials: 1) 60min Ex and 60min recovery (60ER); 2) 3 x 20min Ex separated by 20min recoveries (20ER); 3) 6 x 10min Ex separated by 10min recoveries (10ER), or; 4) 12 x 5min Ex separated by 5min recoveries (5ER). Exercise was performed at a workload of 130 W at 35°C. Whole-body heat exchange was determined by direct calorimetry. Core temperature, SR (ventilated capsule), and SkBF (laser-doppler) were measured continuously. Evaporative heat loss (EHL) progressively increased with each ER, such that it was significantly greater (p≤0.05) at the end of the last compared to the first Ex for 5ER (299±39 vs. 440±41 W), 10ER (425±51 vs. 519±45 W), and 20ER (515±63 vs. 575±74 W). The slope of the EHL response against esophageal temperature significantly increased from the first to the last Ex within the 10ER (376±56 vs. 445±89 W⋅°C(-1), p≤0.05) and 20ER (535±85 vs. 588±28 W⋅°C(-1), p≤0.05) conditions, but not during 5ER (296±96 W⋅°C(-1) vs. 278±95 W⋅°C(-1), p=0.237). In contrast, the slope of the SkBF response against esophageal temperature did not significantly change from the first to the last Ex (5ER: 51±23 vs. 54±19 %⋅°C(-1), p=0.848; 10ER: 53±8 vs. 56±21 %⋅°C(-1), p=0.786; 20ER: 44±20 vs. 50±27 %⋅°C(-1), p=0.432). Overall, no differences in body heat content and core temperature were observed. These results suggest that altered local and whole-body heat loss responses do not explain the previously observed greater core temperatures during intermittent exercise. |
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Authors:
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Daniel Gagnon; Glen P Kenny |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-1-26 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: - ISSN: 1522-1490 ISO Abbreviation: - Publication Date: 2011 Jan |
Date Detail:
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Created Date: 2011-1-28 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Ottawa. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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