| Whole body hypothermia has central and peripheral influences on elbow flexor performance. | |
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MedLine Citation:
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PMID: 21378082 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The superimposed twitch (SIT) technique was used to study the effect of whole body hypothermia on maximal voluntary activation of elbow flexors. Seven subjects [26.4±4 (SD) yr] were exposed to 60 minutes of either immersion in 8°C water (Hypothermia), or sitting in 22°C air (Control). Voluntary activation was assessed during brief (3 s) maximal voluntary contractions (MVC) and then during a 2-minute fatiguing sustained MVC. Hypothermia (core temperature = 34.8±0.9°C) decreased maximal voluntary torque from 98.2±1.0 to 82.8±5.8%MVC (P<0.001) and increased central conduction time from 7.9±0.4 ms to 9.1±0.7 ms (P<0.05). Hypothermia also decreased maximal resting twitch amplitude from 17.6±4.0 to 10.0±1.7%MVC (P<0.005) and increased the time to peak twitch tension from 55.4±4.0 to 79.0±11.7 ms (P<0.001). During the 2-min contraction, hypothermia decreased initial torque (p<0.01) but attenuated the subsequent rate of torque decline (Control: 95.5±4 to 29.4±8 %MVC; Hypothermia: 85.3±8 to 37.3±5%MVC, P<0.01). Cortical SITs increased as fatigue developed but were always lower in the Hypothermia condition. Cortical SITs increased from a pre-fatigue value of 0.4±0.3%MVC to 3.9±1.4%MVC post-fatigue (P<0.001) in the Hypothermia condition, and from 1.7±0.9%MVC to 5.5±2.3%MVC in the control. Our results suggest that hypothermia decreases MVCs primarily via peripheral mechanisms and attenuates the rate of fatigue development by reducing central fatigue. |
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Authors:
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Farrell Cahill; Jayne M Kalmar; Thea Pretorius; Phillip F Gardiner; Gordon G Giesbrecht |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-3-4 |
Journal Detail:
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Title: Experimental physiology Volume: - ISSN: 1469-445X ISO Abbreviation: - Publication Date: 2011 Mar |
Date Detail:
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Created Date: 2011-3-7 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9002940 Medline TA: Exp Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1 University of Manitoba; |
Export Citation:
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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