Document Detail

Acoustic myography of the human quadriceps muscle during intermittent fatiguing activity.
MedLine Citation:
PMID:  1517765     Owner:  NLM     Status:  MEDLINE    
Integrated acoustic myography (IAMG) and electromyography (IEMG) were recorded over rectus femoris (RF) in six healthy subjects during a series of intermittent isometric contractions of quadriceps. Contractions were held for 10 sec with 10 sec rest between each, commencing at 75% maximum voluntary contraction (MVC) force and continuing to 40% MVC. The IAMG activity initially decreased (75%-60% MVC) in a linear relationship (r = 0.9) with fatigue (i.e. force loss) but then plateaued and increased once force fell below 52% MVC. The AMG/force relationship for the whole fatiguing protocol (i.e. 75%-40% MVC) was quadratic (r = 0.87). The IEMG also showed a quadratic relationship with force (r = 0.85) but activity initially increased before decreasing. The results of the present study quantify the relationship between AMG and force in quadriceps during fatigue from intermittent contractions commencing at 75% MVC. The findings confirm previous observations that AMG decreases with fatigue during strong contractions but the quadratic relationship found in the present study differs to that for other muscles during sustained contractions. The results also suggest that simultaneous recordings of AMG and EMG may help distinguish central and peripheral fatigue. Acoustic myography may therefore be a useful non-invasive monitor of force during early fatiguing activity using the present protocol but the need to study AMG during fatigue of different muscles and force levels is stressed.
P A Dalton; M J Comerford; M J Stokes
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the neurological sciences     Volume:  109     ISSN:  0022-510X     ISO Abbreviation:  J. Neurol. Sci.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-10-06     Completed Date:  1992-10-06     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375403     Medline TA:  J Neurol Sci     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  56-60     Citation Subset:  IM    
Department of Physiotherapy, University of Queensland, Brisbane, Australia.
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MeSH Terms
Fatigue / physiopathology
Isometric Contraction*
Motor Neurons / physiology
Muscles / physiopathology
Myography / methods*

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

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