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| Research article summary (published 29 Nov 2002): |
Changes in center-of-pressure dynamics during upright standing related to decreased balance control in young adults: fractional Brownian motion analysis.
Full Abstract
We investigated the relationships between the ability to maintain balance in an upright stance and center-of-pressure (COP) dynamic properties in young adults. Included in this study were 10 healthy male subjects in each of two groups with respect to balance ability. Balance ability was evaluated according to the length of time a subject stood on one leg with his eyes closed. The means and ranges of this one-leg balancing time were 17.9 s (3-43 s) and 118.3 s (103-120 s) for the off-balance and balance groups, respectively. The time-varying displacements of the COP under a subject's feet during quiet two-leg (normal) standing were measured by an instrumented force platform. Each subject was tested in both the eyes-open and eyes-closed conditions. The COP trajectories were analyzed as fractional Brownian motions according to the procedure of 'stabilogram-diffusion analysis', proposed by Collins and De Luca (1993). The extracted parameters were the effective diffusion coefficients (D) for the short-term (less than about 1.0 s) and long-term intervals, respectively, as well as the Hurst exponents (H) for the short-term and long-term intervals, and some critical-point coordinates (i.e., critical mean square displacements and critical time intervals). The off-balance group showed significantly higher values for short-term D, short-term H, and critical mean square displacements than the balance group. No significant differences between the groups were found in the long-term D and H or in the critical time intervals. That is, for the off-balance subjects, an increase in the stochastic activity and positively correlated (persistent) behavior of the postural sway during shorter timescales may cause postural instability. These results suggest that the difference in balance ability for young adults is related to the open-loop (i.e., short-term) control mechanisms but not to the corrective feedback (i.e., long-term) mechanisms used to maintain balance in an upright stance.
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Author information
Author/s: Tanaka, Hideyuki (H); Uetake, Teruo (T); Kuriki, Satoshi (S); Ikeda, Satoshi (S);
Affiliation: Department of Human-Computer Interaction Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan. tanahide(-atsign-)cc.tuat.ac.jp
Journal and publication information
Publication Type: Journal Article; Research Support, Non-U.S. Gov't
Journal: Journal of human ergology (J Hum Ergol (Tokyo)), published in Japan. (Language: eng)
Reference: 2002-Dec; vol 31 (issue 1-2) : pp 1-11
Dates: Created 2003/08/11; Completed 2003/09/10; Revised 2006/11/15;
PMID: 12908330, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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