| Heat acclimation improves exercise performance. | |
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MedLine Citation:
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PMID: 20724560 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study examined the impact of heat acclimation on improving exercise performance in cool and hot environments. Twelve trained cyclists performed tests of maximal aerobic power (VO2max), time-trial performance, and lactate threshold, in both cool [13°C, 30% relative humidity (RH)] and hot (38°C, 30% RH) environments before and after a 10-day heat acclimation (∼50% VO2max in 40°C) program. The hot and cool condition VO2max and lactate threshold tests were both preceded by either warm (41°C) water or thermoneutral (34°C) water immersion to induce hyperthermia (0.8-1.0°C) or sustain normothermia, respectively. Eight matched control subjects completed the same exercise tests in the same environments before and after 10 days of identical exercise in a cool (13°C) environment. Heat acclimation increased VO2max by 5% in cool (66.8 ± 2.1 vs. 70.2 ± 2.3 ml·kg(-1)·min(-1), P = 0.004) and by 8% in hot (55.1 ± 2.5 vs. 59.6 ± 2.0 ml·kg(-1)·min(-1), P = 0.007) conditions. Heat acclimation improved time-trial performance by 6% in cool (879.8 ± 48.5 vs. 934.7 ± 50.9 kJ, P = 0.005) and by 8% in hot (718.7 ± 42.3 vs. 776.2 ± 50.9 kJ, P = 0.014) conditions. Heat acclimation increased power output at lactate threshold by 5% in cool (3.88 ± 0.82 vs. 4.09 ± 0.76 W/kg, P = 0.002) and by 5% in hot (3.45 ± 0.80 vs. 3.60 ± 0.79 W/kg, P < 0.001) conditions. Heat acclimation increased plasma volume (6.5 ± 1.5%) and maximal cardiac output in cool and hot conditions (9.1 ± 3.4% and 4.5 ± 4.6%, respectively). The control group had no changes in VO2max, time-trial performance, lactate threshold, or any physiological parameters. These data demonstrate that heat acclimation improves aerobic exercise performance in temperate-cool conditions and provide the scientific basis for employing heat acclimation to augment physical training programs. |
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Authors:
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Santiago Lorenzo; John R Halliwill; Michael N Sawka; Christopher T Minson |
Publication Detail:
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Type: Journal Article; Randomized Controlled Trial; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2010-08-19 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 109 ISSN: 1522-1601 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-10-13 Completed Date: 2011-05-23 Revised Date: 2012-05-07 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 1140-7 Citation Subset: IM |
Affiliation:
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Dept. of Human Physiology, Univ. of Oregon, Eugene, OR 97403-1240, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acclimatization* Adaptation, Physiological Adolescent Adult Anaerobic Threshold Bicycling Cardiac Output Cold Temperature Exercise* Female Heart Rate Hot Temperature* Humans Hyperthermia, Induced* Lactic Acid / blood Male Muscle Contraction* Muscle Strength Muscle, Skeletal / metabolism* Oxygen Consumption* Plasma Volume Time Factors Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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HL-081671/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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50-21-5/Lactic Acid |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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