Document Detail

The effects of visual input on postural control of the lumbar spine in unstable sitting.
MedLine Citation:
PMID:  12967756     Owner:  NLM     Status:  MEDLINE    
Postural control of the lumbar spine in unstable sitting was quantified through the analysis of the center of pressure (CoP) movement recorded by a force plate situated underneath a seat that incorporated a hemisphere. Thirteen healthy subjects were tested under conditions of increasing seat instability and elimination of visual input. The purpose of this study was to determine the relative effects of visual input and support surface instability on open and closed loop postural control mechanisms in sitting and to determine the association between traditional summary statistics and random walk analysis of CoP movement. The effects of the seat instability level and visual input on the CoP movement parameters were tested with a two-factor, repeated measures ANOVA (p<0.01). In all summary statistics CoP movement parameters increased significantly due to the seat instability level and lack of visual input. The random walk analysis identified two regions, short- and long-term, which has been postulated to represent open and closed loop control mechanism, respectively. While short-term scaling exponents were independent from visual input, CoP displacement in the short-term region was significantly increased in the eyes closed condition. Summary statistic of CoP total path length per second correlated highly with critical point coordinates and short-term diffusion coefficients. The CoP movement in the long-term region was consistent with a closed loop control mechanisms. The findings of visual influence on what is assumed as an open-loop control mechanism does not, at face value, support the hypothesis that two separate mechanisms are working to achieve postural control.
Sheri P Silfies; Jacek Cholewicki; Andrea Radebold
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Human movement science     Volume:  22     ISSN:  0167-9457     ISO Abbreviation:  Hum Mov Sci     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-09-11     Completed Date:  2004-02-06     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8300127     Medline TA:  Hum Mov Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  237-52     Citation Subset:  IM    
Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, P.O. Box 208071, New Haven, CT 06520, USA.
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MeSH Terms
Lumbar Vertebrae / physiology*
Postural Balance*
Posture / physiology*
Visual Perception*
Grant Support

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