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Sensitivity and reliability of local dynamic stability: effects of age and altered sensory conditions.

Authors
Kim-S; Nussbaum-MA
Source
Proceedings of the Human Factors and Ergonomics Society 51st Annual Meeting, October 1-5, 2007, Baltimore, Maryland. Santa Monica, CA: Human Factors and Ergonomics Society, 2007 Oct; 51(15):899-903
NIOSHTIC No.
20040997
Abstract
Local dynamic stability was investigated during quiet upright stance with respect to age and altered sensory conditions. From center of pressure (COP) trajectories, the largest Lyapunov exponent (xmax) was extracted to directly parameterize local dynamic stability, and the reliability of xmax was assessed using the intra-class correlation coefficient (ICC). Thirty two participants volunteered for upright quiet stance trials. Vision and somatosenstaion were experimentally altered: vision was modified by eye closure, and somatosensation by using both a hard surface (HS) and a soft surface (SS). Age and vision had main effects on xma, and the age x vision and vision x surface interaction effects were also significant. In general, older participants were less stable (i.e., higher xmax) than younger, and altered sensory information resulted in a decrease in stability. Reliability was higher for older versus younger participants. Use of xmax enabled a direct assessment of age-related differences in local dynamic stability and effects of altered sensory conditions. Such non-linear measures can provide additional information to that available from traditional COP-based analyses.
Keywords
Posture; Humans; Men; Women; Age-groups; Musculoskeletal-system; Muscles; Muscle-physiology; Muscle-function; Physical-capacity; Physical-fitness; Physiological-factors; Physiological-function; Physiological-response; Physiology; Sensory-perceptual-processes
CODEN
PHFSDQ
Publication Date
20071001
Document Type
Conference/Symposia Proceedings
Funding Type
Grant
Fiscal Year
2008
NTIS Accession No.
NTIS Price
ISBN No.
9788945289308
Identifying No.
Grant-Number-R01-OH-004089; Grant-Number-R01-OH-007882
Issue of Publication
15
ISSN
1071-1813
Source Name
Proceedings of the Human Factors and Ergonomics Society 51st Annual Meeting, October 1-5, 2007, Baltimore, Maryland
State
MD; VA
Performing Organization
Virginia Polytechnic Institute and State University
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