Document Detail


A novel shoulder-elbow mechanism for increasing speed in a multijoint arm movement.
MedLine Citation:
PMID:  20454785     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The speed of arm movements is normally increased by increasing agonist muscle activity, but in overarm throwing, an additional effect on speed may come from exploitation of interaction torques (a passive torque associated with motion at adjacent joints). We investigated how the central nervous system (CNS) controls interaction torques at the shoulder and elbow to increase speed in 2-D overarm throwing. Twelve experienced throwers made slow, medium, and fast 2-D throws in a parasagittal plane. Joint motions were computed from recordings made with search coils; joint torques were calculated using inverse dynamics. For slow and medium-speed throws, elbow extension was primarily produced by elbow muscle torque. For fast throws, there was an additional late-occurring elbow extensor interaction torque. Parceling out this elbow extension interaction torque revealed that it primarily arose from shoulder extension deceleration. Surprisingly, shoulder deceleration before ball release was not caused by shoulder flexor (antagonist) muscle torque. Rather, shoulder deceleration was produced by passive elbow-to-shoulder interaction torques that were primarily associated with elbow extension acceleration and velocity. It is concluded that when generating fast 2-D throws, the CNS utilized the arm's biomechanical properties to increase ball speed. It did this by coordinating shoulder and elbow motions such that an instantaneous mechanical positive feedback occurred of interaction torques between shoulder and elbow before ball release. To what extent this mechanism is utilized in other fast multijoint arm movements remains to be determined.
Authors:
Derek B Debicki; Sherry Watts; Paul L Gribble; Jon Hore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-08
Journal Detail:
Title:  Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale     Volume:  203     ISSN:  1432-1106     ISO Abbreviation:  Exp Brain Res     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-25     Completed Date:  2010-09-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  601-13     Citation Subset:  IM    
Affiliation:
Department of Physiology and Pharmacology, The University of Western Ontario, Medical Science Bldg, London, ON, N6A 5C1, Canada.
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MeSH Terms
Descriptor/Qualifier:
Analysis of Variance
Arm / physiology*
Biomechanics
Brain / physiology
Elbow / physiology*
Elbow Joint / physiology
Feedback, Physiological
Humans
Male
Movement / physiology*
Muscle, Skeletal / physiology
Shoulder / physiology*
Shoulder Joint / physiology
Spinal Cord / physiology
Torque
Young Adult
Grant Support
ID/Acronym/Agency:
//Canadian Institutes of Health Research

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


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