Document Detail

Whole body hypothermia has central and peripheral influences on elbow flexor performance.
MedLine Citation:
PMID:  21378082     Owner:  NLM     Status:  Publisher    
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.
Farrell Cahill; Jayne M Kalmar; Thea Pretorius; Phillip F Gardiner; Gordon G Giesbrecht
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-4
Journal Detail:
Title:  Experimental physiology     Volume:  -     ISSN:  1469-445X     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-7     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1 University of Manitoba;
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