Document Detail

Intramuscular and surface electromyogram changes during muscle fatigue.
MedLine Citation:
PMID:  3700300     Owner:  NLM     Status:  MEDLINE    
Twelve male subjects were tested to determine the effects of motor unit (MU) recruitment and firing frequency on the surface electromyogram (EMG) frequency power spectra during sustained maximal voluntary contraction (MVC) and 50% MVC of the biceps brachii muscle. Both the intramuscular MU spikes and surface EMG were recorded simultaneously and analyzed by means of a computer-aided intramuscular spike amplitude-frequency histogram and frequency power spectral analysis, respectively. Results indicated that both mean power frequency (MPF) and amplitude (rmsEMG) of the surface EMG fell significantly (P less than 0.001) together with a progressive reduction in MU spike amplitude and firing frequency during sustained MVC. During 50% MVC there was a significant decline in MPF (P less than 0.001), but this decline was accompanied by a significant increase in rmsEMG (P less than 0.001) and a progressive MU recruitment as evidenced by an increased number of MUs with relatively large spike amplitude. Our data suggest that the surface EMG amplitude could better represent the underlying MU activity during muscle fatigue and the frequency powers spectral shift may or may not reflect changes in MU recruitment and rate-coding patterns.
T Moritani; M Muro; A Nagata
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  60     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1986 Apr 
Date Detail:
Created Date:  1986-06-09     Completed Date:  1986-06-09     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1179-85     Citation Subset:  IM    
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MeSH Terms
Action Potentials
Electromyography / methods*
Fatigue / physiopathology*
Muscle Contraction*
Muscles / physiology*

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

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