Muscle glycogen reduction in man: relationship between surface EMG activity and oxygen uptake kinetics during heavy exercise

Osborne, Mark A. and Schneider, Donald A. (2006) Muscle glycogen reduction in man: relationship between surface EMG activity and oxygen uptake kinetics during heavy exercise. Experimental Physiology, 91 1: 179-189. doi:10.1113/expphysiol.2005.031450


Author Osborne, Mark A.
Schneider, Donald A.
Title Muscle glycogen reduction in man: relationship between surface EMG activity and oxygen uptake kinetics during heavy exercise
Journal name Experimental Physiology   Check publisher's open access policy
ISSN 0958-0670
1469-445X
Publication date 2006-01
Sub-type Article (original research)
DOI 10.1113/expphysiol.2005.031450
Volume 91
Issue 1
Start page 179
End page 189
Total pages 11
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Subject 110602 Exercise Physiology
Abstract The purpose of this study was to determine whether muscle glycogen reduction prior to exercise would alter muscle fibre recruitment pattern and change either on-transient O2 uptake ( ) kinetics or the slow component. Eight recreational cyclists ( , 55.6 ± 1.3 ml kg −1 min−1) were studied during 8 min of heavy constant-load cycling performed under control conditions (CON) and under conditions of reduced type I muscle glycogen content (GR). was measured breath-by-breath for the determination of kinetics using a double-exponential model with independent time delays. was higher in the GR trial compared to the CON trial as a result of augmented phase I and II amplitudes, with no difference between trials in the phase II time constant or the magnitude of the slow component. The mean power frequency (MPF) of electromyography activity for the vastus medialis increased over time during both trials, with a greater rate of increase observed in the GR trial compared to the CON trial. The results suggest that the recruitment of additional type II motor units contributed to the slow component in both trials. An increase in fat metabolism and augmented type II motor unit recruitment contributed to the higher in the GR trial. However, the greater rate of increase in the recruitment of type II motor units in the GR trial may not have been of sufficient magnitude to further elevate the slow component when was already high and approaching .
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Human Movement and Nutrition Sciences Publications
 
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Created: Fri, 20 Mar 2009, 11:56:29 EST by Paul Rollo on behalf of School of Human Movement and Nutrition Sciences