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Effects of perturbation magnitude on dynamic stability when walking in destabilizing environments.
MedLine Citation:
PMID:  22749389     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
External perturbations applied to the walking surface or visual field can challenge an individual's ability to maintain stability during walking. Accurately quantifying and predicting changes in stability during walking will further our understanding of how individuals respond to challenges encountered during daily life and guide the development of assessments and rehabilitation interventions for individuals at increased risk of falling. This study is the first to determine how orbital and local dynamic stability metrics, including maximum Floquet multipliers and local divergence exponents, change in response to continuous mediolateral visual and surface perturbations of different amplitudes. Eleven healthy individuals walked in a fully immersive virtual environment. Participants completed two 3-min walking trials each under the following nine conditions: no perturbations, surface perturbations at each of 3 amplitudes, and visual perturbations at each of 5 amplitudes. All perturbations were applied as continuous pseudo-random oscillations. During both surface and visual perturbations, individuals were significantly more orbitally and locally unstable compared to un-perturbed walking. As walking surface perturbation amplitudes increased, individuals were more orbitally (but not locally) unstable. As visual perturbation amplitudes increased, individuals were more locally (but not orbitally) unstable between lower and higher amplitudes. Overall, these dynamic stability metrics were much less sensitive to changes in perturbation amplitudes than to differences between un-perturbed and perturbed walking, or to differences between mechanical and visual perturbations. This suggests that the type of perturbation(s) applied has a far greater impact than the magnitude of those perturbations in determining the response that will be elicited.
Authors:
Emily H Sinitksi; Kevin Terry; Jason M Wilken; Jonathan B Dingwell
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-28
Journal Detail:
Title:  Journal of biomechanics     Volume:  -     ISSN:  1873-2380     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-7-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Elsevier Ltd. All rights reserved.
Affiliation:
Center for the Intrepid, Department of Orthopaedics and Rehabilitation, Brooke Army Medical Center, Ft. Sam Houston, TX 78234, USA.
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