Document Detail

Patterns of motor recruitment can be determined using surface EMG.
MedLine Citation:
PMID:  18029198     Owner:  NLM     Status:  MEDLINE    
Previous studies have reported how different populations of motor units (MUs) can be recruited during dynamic and locomotor tasks. It was hypothesised that the higher-threshold units would contribute higher-frequency components to the sEMG spectra due to their faster conduction velocities, and thus recruitment patterns that increase the proportion of high-threshold units active would lead to higher-frequency elements in the sEMG spectra. This idea was tested by using a model of varying recruitment coupled to a three-layer volume conductor model to generate a series of sEMG signals. The recruitment varied from (A) orderly recruitment where the lowest-threshold MUs were initially activated and higher-threshold MUs were sequentially recruited as the contraction progressed, (B) a recurrent inhibition model that started with orderly recruitment, but as the higher-threshold units were activated they inhibited the lower-threshold MUs (C) nine models with intermediate properties that were graded between these two extremes. The sEMG was processed using wavelet analysis and the spectral properties quantified by their mean frequency, and an angle theta that was determined from the principal components of the spectra. Recruitment strategies that resulted in a greater proportion of faster MUs being active had a significantly lower theta and higher mean frequency.
James M Wakeling
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Publication Detail:
Type:  Journal Article     Date:  2007-10-29
Journal Detail:
Title:  Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology     Volume:  19     ISSN:  1873-5711     ISO Abbreviation:  J Electromyogr Kinesiol     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-02-09     Completed Date:  2009-06-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9109125     Medline TA:  J Electromyogr Kinesiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  199-207     Citation Subset:  IM    
School of Kinesiology, Simon Fraser University, Burnaby, BC, Canada V5A 1S6.
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MeSH Terms
Computer Simulation
Electromyography / methods*
Models, Neurological*
Motor Neurons / physiology*
Muscle Contraction / physiology*
Muscle, Skeletal / physiology*
Neuromuscular Junction / physiology*
Recruitment, Neurophysiological / physiology*

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