Document Detail

Effect of glycogen depletion on the oxygen uptake slow component in humans.
MedLine Citation:
PMID:  15241714     Owner:  NLM     Status:  MEDLINE    
Previous studies have indicated that the (.-)VO(2) slow component is related to the recruitment of type II muscle fibres. We therefore hypothesised that an exercise and dietary regimen designed to deplete type I muscle fibres of glycogen would result in a greater contribution of type II muscle fibres to the exercise power output and therefore a larger amplitude of the (.-)VO(2) slow component. Eight male subjects took part in this study. On day 1, the subjects reported to the laboratory at 8 a.m., and completed a 9 min constant-load cycling test at a work rate equivalent to 85 % (.-)VO(2) peak. On day 2 at 12 p.m., the subjects were fed a 4200 kJ meal (60 % protein, 40 % fat); at 6 p.m. they completed a 2 h cycling test at 60 % (.-)VO(2) peak. On day 3 at 8 a.m., the subjects performed an exercise test identical to that of day 1. Metabolic and respiratory measurements indicated that our experimental design was effective in reducing the muscle glycogen content. (.-)VO(2) was significantly higher (by approximately 140 ml x min (-1)) throughout exercise following glycogen depletion but no appreciable changes in (.-)VO(2) kinetics were found: neither the time constant of the primary response (from 35.4 +/- 2.5 to 33.2 +/- 4.4 s) nor the amplitude of the slow component (from 404 +/- 95 to 376 +/- 81 ml x min (-1)) was significantly altered. Therefore, we suggest that the increased (.-)VO(2) throughout exercise and the unaltered (.-)VO(2) slow component following glycogen depletion might be explained by a shift towards a greater reliance on fat metabolism in type I muscle fibres with no appreciable change in fibre type recruitment patterns.
J Bouckaert; A M Jones; K Koppo
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Publication Detail:
Type:  Clinical Trial; Journal Article    
Journal Detail:
Title:  International journal of sports medicine     Volume:  25     ISSN:  0172-4622     ISO Abbreviation:  Int J Sports Med     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-07-08     Completed Date:  2004-10-19     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8008349     Medline TA:  Int J Sports Med     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  351-6     Citation Subset:  IM    
Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
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MeSH Terms
Exercise / physiology*
Exercise Test
Glycogen / metabolism*
Muscle Fibers, Slow-Twitch / metabolism,  physiology*
Oxygen Consumption / physiology*
Reg. No./Substance:

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