Document Detail

Postural adjustments associated with rapid voluntary arm movements. II. Biomechanical analysis.
MedLine Citation:
PMID:  3346688     Owner:  NLM     Status:  MEDLINE    
Normal subjects performed bilaterally symmetric rapid elbow flexions or extensions ("focal movements") while standing. Specific patterns of electromyographic activity in leg and trunk muscles ("associated postural adjustments") were seen for each type of movement. The biomechanical significance of these postural adjustments was analysed by means of the ground reaction forces and motion of the various body segments. Experimental data were compared with that from a theoretical model of the body consisting of a six segment kinetic chain with rigid links. Distinct patterns of the ground reaction forces with elbow flexion were opposite in direction to those seen with elbow extension. Movements of the various body segments were small and specific for a certain focal movement. Dynamic perturbations arising from the arm movement in an anteroposterior direction were found to be compensated by postural adjustments, whereas vertical perturbations were not compensated. The muscular activity acting about different joints in the different movements was found to correlate with the predictions of activity needed to compensate for net joint reaction moments arising from the focal movement. Motion of the various body segments could be understood as resulting from the interplay of the net reaction moments and the net muscular moments at the different joints. Dynamic postural requirements are accomplished by a precise active compensation initiated before the focal movement.
W G Friedli; L Cohen; M Hallett; S Stanhope; S R Simon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of neurology, neurosurgery, and psychiatry     Volume:  51     ISSN:  0022-3050     ISO Abbreviation:  J. Neurol. Neurosurg. Psychiatr.     Publication Date:  1988 Feb 
Date Detail:
Created Date:  1988-04-11     Completed Date:  1988-04-11     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985191R     Medline TA:  J Neurol Neurosurg Psychiatry     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  232-43     Citation Subset:  IM    
Department of Orthopedic Surgery, Children's Hospital Medical Center, Boston, MA.
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MeSH Terms
Elbow / innervation*
Middle Aged
Motor Activity / physiology*
Motor Neurons / physiology*
Muscle Contraction
Muscles / innervation*

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

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