Document Detail

Motor unit recruitment and the gradation of muscle force.
MedLine Citation:
PMID:  8248292     Owner:  NLM     Status:  MEDLINE    
The capabilities of the different types of motor units are reviewed, and their properties in a variety of muscles are discussed. Because the tension-generating capacities of motor units are so different, the order in which they are recruited will have a strong influence on the way force output of the whole muscle is graded. Activation of motor units in a random order produces a roughly linear force increase with progressive recruitment, whereas recruitment of motor units in order of increasing force produces an approximately exponential force increase as the number of active motor units increases. The latter scheme allows fine control of weak movements and rapid production of powerful movements. Motor units are shown to be well adapted to the tasks they must perform, and a "compromise" motor unit will not fulfill all the tasks demanded of it. Finally, changes in motor unit properties produced by different activity patterns and by muscle reinnervation are reviewed, and the implications for rehabilitation are discussed.
H P Clamann
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Physical therapy     Volume:  73     ISSN:  0031-9023     ISO Abbreviation:  Phys Ther     Publication Date:  1993 Dec 
Date Detail:
Created Date:  1993-12-29     Completed Date:  1993-12-29     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0022623     Medline TA:  Phys Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  830-43     Citation Subset:  AIM; IM; S    
Department of Physiology, University of Berne, Switzerland.
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MeSH Terms
Adaptation, Physiological
Models, Neurological
Motor Neurons / physiology*
Motor Skills
Movement / physiology
Muscle Contraction / physiology*
Muscles / anatomy & histology*,  innervation*,  physiology
Myofibrils / classification,  physiology
Physical Exertion
Recruitment, Neurophysiological / physiology*
Time Factors

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

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