Document Detail

Human motor unit activity during concentric and eccentric movements.
MedLine Citation:
PMID:  11039116     Owner:  NLM     Status:  MEDLINE    
Single motor units (MUs) activity was investigated in human m. biceps brachii during movements against an elastic load. A total of sixty-five MUs were studied by means of subcutaneously placed fine-wire branched electrodes. Subjects were asked to perform active shortening and lengthening of the muscle with approximately constant velocities at two different speeds--slow and fast. Both recruitment (RT) and decruitment (DT) thresholds of MU were found to be lower in movement with higher velocity. The recruitment order of MUs was approximately one and the same during concentric movements with a different but constant velocity. The firing onset of MUs is organized so that the peak of the first twitch contraction occurs at approximately the same force level irrespective of how fast the movement is. In contrast, during the eccentric movements the peak of the last twitch contraction of MU occurs at different torque levels depending on the velocity. The decruitment of the MUs during eccentric movement was in a reverse order to their recruitment during concentric movements. Generally, at one and the same velocity the RT of a given MU was lower than DT. Nevertheless, the peaks of the first and the last twitch contractions during concentric and eccentric movements with one and the same velocity occurred at approximately one and the same torque level.
P Christova; A Kossev
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Electromyography and clinical neurophysiology     Volume:  40     ISSN:  0301-150X     ISO Abbreviation:  Electromyogr Clin Neurophysiol     Publication Date:  2000 Sep 
Date Detail:
Created Date:  2001-01-17     Completed Date:  2001-02-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0327533     Medline TA:  Electromyogr Clin Neurophysiol     Country:  BELGIUM    
Other Details:
Languages:  eng     Pagination:  331-8     Citation Subset:  IM    
Institute of Biophysics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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MeSH Terms
Arm / physiology
Electrodes, Implanted
Electromyography / instrumentation
Linear Models
Middle Aged
Motor Neurons / physiology*
Muscle Contraction / physiology*
Muscle, Skeletal / innervation,  physiology*
Recruitment, Neurophysiological / physiology
Stress, Mechanical

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

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