Complexity of human postural control in young and older adults during prolonged standing

Autor(es)

Duarte, Marcos ^[1] ; Sternad, Dagmar ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Phys Educ & Sport, Sao Paulo - Brazil

^[2] Penn State Univ, Dept Kinesiol & Integrat Biosci, University Pk, PA 16802 - USA

• Tipo de documento: Artigo Científico
• Fonte: Experimental Brain Research; v. 191, n. 3, p. 265-276, NOV 2008.
• Citações Web of Science: 102

Resumo

Aging is known to have a degrading influence on many structures and functions of the human sensorimotor system. The present work assessed aging-related changes in postural sway using fractal and complexity measures of the center of pressure (COP) dynamics with the hypothesis that complexity and fractality decreases in the older individuals. Older subjects (68 +/- 4 years) and young adult subjects (28 +/- 7 years) performed a quiet stance task (60 s) and a prolonged standing task (30 min) where subjects were allowed to move freely. Long-range correlations (fractality) of the data were estimated by the detrended fluctuation analysis (DFA); changes in entropy were estimated by the multi-scale entropy (MSE) measure. The DFA results showed that the fractal dimension was lower for the older subjects in comparison to the young adults but the fractal dimensions of both groups were not different from a 1/f noise, for time intervals between 10 and 600 s. The MSE analysis performed with the typically applied adjustment to the criterion distance showed a higher degree of complexity in the older subjects, which is inconsistent with the hypothesis that complexity in the human physiological system decreases with aging. The same MSE analysis performed without adjustment showed no differences between the groups. Taken all results together, the decrease in total postural sway and long-range correlations in older individuals are signs of an adaptation process reflecting the diminishing ability to generate adequate responses on a longer time scale. (AU)

• Processo FAPESP: 04/10917-0 - Mecanismos de controle do equilíbrio em adultos e idosos durante as posturas ereta quieta e irrestrita
• Beneficiário: Marcos Duarte
• Modalidade de apoio: Auxílio à Pesquisa - Regular