Document Detail

Relationship between electromyographic activity of the vastus lateralis while standing and the extent of bilateral simulated knee-flexion contractures.
MedLine Citation:
PMID:  1741999     Owner:  NLM     Status:  MEDLINE    
The effect of simulated bilateral knee-flexion contractures (KFC) on the electromyographic (EMG) activity of the vastus lateralis was studied by testing 10 normal subjects using surface EMG to test the hypothesis that the activity of the knee extensors would increase as a function of the severity of the contracture. The root mean square of the EMG activity was determined from four 4-s samples taken at 30-s intervals, during 2 min of standing in each of five positions of simulated KFC (0 degree, 10 degrees, 20 degrees, 30 degrees and 40 degrees). A randomly balanced order of conditions was used. KFC were simulated in each subject by means of an adjustable line from the subject's waist to the sole of each foot. An analysis of variance was used to contrast EMG activity, and a significant difference was found between each of the positions (P less than 0.05). The mean (+/- 1 SD) EMG activity, expressed as a percentage of the maximum voluntary contraction, was 0.3% (+/- 0.2) at 0 degree, 7.6% (+/- 5.6) at 10 degrees, 10.9% (+/- 7.6) at 20 degrees, 16.6% (+/- 12.4) at 30 degrees and 24.0% (+/- 14.0) at 40 degrees. A linear relationship was found (r2 = 0.986), expressed by the equation y = 0.62 + 0.56 x, where y represents EMG activity and x represents the extent of simulated KFC (P = 0.0007). The results provide insight into the increased knee extensor activity necessary to stand with KFC and underline the importance of treating this common disorder.
P J Potter; R L Kirby
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of physical medicine & rehabilitation / Association of Academic Physiatrists     Volume:  70     ISSN:  0894-9115     ISO Abbreviation:  Am J Phys Med Rehabil     Publication Date:  1991 Dec 
Date Detail:
Created Date:  1992-01-16     Completed Date:  1992-01-16     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8803677     Medline TA:  Am J Phys Med Rehabil     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  301-5     Citation Subset:  AIM; IM    
Department of Physical Medicine and Rehabilitation, Faculty of Medicine, University of Western Ontario, London, Canada.
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MeSH Terms
Analysis of Variance
Contracture / physiopathology*
Knee Joint / physiopathology*
Muscle Contraction*
Regression Analysis

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

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