Document Detail

Influence of an asymmetrical body weight distribution on the control of undisturbed upright stance.
MedLine Citation:
PMID:  16084204     Owner:  NLM     Status:  MEDLINE    
Postural asymmetry in humans is generally associated with different pathologies. However, its specific influence on undisturbed upright stance is poorly understood. To evaluate its separate effects on each support, the centre of pressure (CP) displacements were recorded through two force platforms. In a second step, the complex resultant centre of pressure trajectories (CP(Res)) were computed and decomposed into two elementary components: the horizontal displacements of the centre of gravity (CG(h)) and the difference in the plane of support between the vertical projection of CG(h) and CP(Res) (CP-CG(v)). These motions were then processed through a frequency analysis and modelled as fractional Brownian motion to gain some additional insight into their spatio-temporal organisation. Ten healthy adults were tested in three conditions consisting of various weight distributions. The quality of the mechanism involved in the control of the unloaded support CP motions appears to decrease as the asymmetry becomes more pronounced. To be precise, larger increases of the CP displacements are observed for the unloaded support compared to the loaded one. As a result, the CP(Res) motions are themselves augmented in the ML direction, inducing in turn larger CG(h) and CP-CG(v) motions. Postural asymmetry thus constitutes an important constraint on the control of upright undisturbed stance by generating changes in the control of both supports and by reducing the efficiency of the hip load/unload mechanisms. On the other hand, by inducing larger body sways, postural asymmetry necessitates higher energy expenditure and the setting of particular control mechanisms.
N Genthon; P Rougier
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Publication Detail:
Type:  Journal Article     Date:  2004-11-25
Journal Detail:
Title:  Journal of biomechanics     Volume:  38     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  2005 Oct 
Date Detail:
Created Date:  2005-08-08     Completed Date:  2005-11-29     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2037-49     Citation Subset:  IM    
Laboratoire de modélisation des activités sportives, Université de Savoie, Domaine scientifique de Savoie-Technolac, Le Bourget du lac, France.
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MeSH Terms
Body Weight*
Models, Statistical
Musculoskeletal Physiological Phenomena
Postural Balance / physiology*
Stress, Mechanical

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

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