Document Detail

Changes in kinematic and EMG variability while practicing a maximal performance task.
MedLine Citation:
PMID:  12223174     Owner:  NLM     Status:  MEDLINE    
This paper examines changes in the variability of electromyographic (EMG) activity and kinematics as a result of practicing a maximal performance task. Eight subjects performed rapid elbow flexion to a target in the horizontal plane. Four hundred trials were distributed equally over four practice sessions. A potentiometer at the elbow axis of rotation of a manipulandum recorded the angular displacement. The EMG activity of the biceps and the triceps brachii was monitored using Beckman surface electrodes. Limb speed increased while both target error and trajectory (velocity versus position) variability decreased. There was an increase in the absolute measure of total EMG variability (the first standard deviation at each point of the biceps and triceps waveform multiplied together). However, the coefficient of variation (the first standard deviation divided by the mean and the result multiplied by 100) of the mean amplitude value of the individual EMG bursts decreased. The variability of triceps motor time also decreased while the variability biceps motor time remained unchanged. The results demonstrated a clear relationship between kinematic and EMG variability. The EMG and the trajectory data suggest that practice resulted in greater central nervous system control over both the spatial-temporal aspects of movement and the magnitude of the biceps and triceps muscle force-impulses.
David A Gabriel
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology     Volume:  12     ISSN:  1050-6411     ISO Abbreviation:  J Electromyogr Kinesiol     Publication Date:  2002 Oct 
Date Detail:
Created Date:  2002-09-11     Completed Date:  2002-12-19     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9109125     Medline TA:  J Electromyogr Kinesiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  407-12     Citation Subset:  IM    
Biomechanics Laboratory, Brock University, St Catharines, ON, Canada L2S 3A1.
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MeSH Terms
Elbow Joint / physiology*
Muscle, Skeletal / physiology*
Practice (Psychology)

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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