Document Detail


Do anticipatory postural adjustments occurring in different segments of the postural chain follow the same organisational rule for different task movement velocities, independently of the inertial load value?
MedLine Citation:
PMID:  10836638     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Dynamic phenomena, termed anticipatory postural adjustments (APA), are known to precede the onset of voluntary movement. Their anticipatory nature confers a particular status on APAs: as they cannot be triggered reflexly by afferent signals induced by a voluntary movement, it can be asked whether the APA parameters are centrally programmed as a function of some task movement parameters or are only the peripheral consequence of control variables. To this end the present study aims to determine whether the APAs occurring at the different sites of the postural chain yield the same accelerometric patterns and follow the same organisational rules when the task movement velocity changes, independently of the inertial load value. Subjects performed unilateral shoulder flexions at maximal and submaximal velocities, with (IUF) and without (OUF) an additional inertial load. Accelerometers were attached to the wrist and trunk, and on both sides of the body at shank, thigh, hip and shoulder. The results show that: 1) there was evidence of anticipatory acceleration in all segments of the postural chain; 2) each acceleration profile for the anticipatory phase was maintained over different focal movement velocities whether there was an additional load or not; 3) there were significant linear relationships between the amplitude of each segmental anticipatory acceleration and the square of the task movement velocity, the slope of which differs as a function of the inertial load; 4) there were close intersegmental correlations between these anticipatory accelerations which did not depend on the inertial load. In addition the correlation between the lower limbs and the opposite side of the body was positive, suggesting a diagonal postural pattern. A comparison of the present kinematic data with the corresponding EMG data reported in the literature argues in favour of a centrally determined kinematic pattern. It is proposed that the diagonal postural pattern between postural segments be considered as one of the order rules which could simplify the control process of asymmetrical movement. The anticipatory kinematics of each of the body segments would be calibrated with the velocity and the inertial load and scaled to the other segments to counteract the perturbing effect of the asymmetrical focal movement on body balance.
Authors:
S Bouisset; J Richardson; M Zattara
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Experimental brain research     Volume:  132     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-08-30     Completed Date:  2000-08-30     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  79-86     Citation Subset:  IM; S    
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MeSH Terms
Descriptor/Qualifier:
Acceleration
Adaptation, Physiological / physiology*
Adult
Female
Humans
Male
Movement / physiology*
Posture / physiology*
Regression Analysis
Shoulder / physiology
Time Factors
Weight Lifting / physiology*

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


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