Document Detail

Motor unit activity and surface electromyogram power spectrum during increasing force of contraction.
MedLine Citation:
PMID:  3569235     Owner:  NLM     Status:  MEDLINE    
Twelve male subjects were tested to determine the relationship between motor unit (MU) activities and surface electromyogram (EMG) power spectral parameters with contractions increasing linearly from zero to 80% of maximal voluntary contraction (MVC). Intramuscular spike and surface EMG signals recorded simultaneously from biceps brachii were analyzed by means of a computer-aided intramuscular MU spike amplitude-frequency (ISAF) histogram and an EMG frequency power spectral analysis. All measurements were made in triplicate and averaged. Results indicate that there were highly significant increases in surface EMG amplitude (71 +/- 31.3 to 505 +/- 188 microV, p less than 0.01) and mean power frequency (89 +/- 13.3 to 123 +/- 23.5 Hz, p less than 0.01) with increasing force. These changes were accompanied by progressive increases in the firing frequency of MU's initially recruited, and of newly recruited MU's with relatively larger spike amplitudes. The group data in the ISAF histograms revealed significant increases in mean spike amplitude (412 +/- 79 to 972 +/- 117 microV, p less than 0.01) and mean firing frequency (17.8 +/- 5.4 to 24.7 +/- 4.1 Hz, p less than 0.01). These data suggest that surface EMG spectral analysis can provide a sensitive measure of the relative changes in MU activity during increasing force output.
T Moritani; M Muro
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of applied physiology and occupational physiology     Volume:  56     ISSN:  0301-5548     ISO Abbreviation:  Eur J Appl Physiol Occup Physiol     Publication Date:  1987  
Date Detail:
Created Date:  1987-06-12     Completed Date:  1987-06-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410266     Medline TA:  Eur J Appl Physiol Occup Physiol     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  260-5     Citation Subset:  IM    
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MeSH Terms
Electrodes, Implanted
Isometric Contraction
Motor Neurons / physiology*
Muscle Contraction*

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