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- Title
Using nonlinear measures to evaluate postural control in healthy adults during bipedal standing on an unstable surface.
- Authors
KĘDZIOREK, JUSTYNA; BŁAŻKIEWICZ, MICHALINA; KACZMARCZYK, KATARZYNA
- Abstract
Purpose: This study examined the use of nonlinear measures - sample entropy (SampEn), fractal dimension (FD), and the Lyapunov exponent (LyE) - to evaluate postural control in adults during standing on an unstable surface, with and without visual feedback. Methods: 14 healthy young adults (24.07 ± 7.32 years) completed bipedal standing trials on an unstable-plate Biodex Balance System (BBS) connected to a Vicon system, with eyes open and closed. Each trial lasted 20 sec. Analysis was performed based on the center of mass (CoM), for which the three nonlinear measures were calculated. Results: Excluding visual feedback was found to cause a significant increase in linear and nonlinear parameters. Moreover, SampEn and FD values were found to be significantly higher in the PD direction, compared to AP or ML, whereas LyE values in this direction were minimal. Conclusions: Results show that the three nonlinear measures provide a useful way of evaluating postural control in healthy adults. Moreover, it seems that introducing an unstable surface meant that the projection of the CoM was not perpendicular to the surface, but rather set at a certain continually changing angle, forcing the whole system to adapt to chaotic and unpredictable conditions. Such refined changes in conditions can be evaluated in a precise way only by using nonlinear measures.
- Subjects
YOUNG adults; CENTER of mass; LYAPUNOV exponents; PSYCHOLOGICAL feedback; FRACTAL dimensions; ADULTS
- Publication
Acta of Bioengineering & Biomechanics, 2022, Vol 24, Issue 1, p9
- ISSN
1509-409X
- Publication type
Article
- DOI
10.37190/ABB-01946-2021-02