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Entropy 2017, 19(2), 76;

A Comparison of Postural Stability during Upright Standing between Normal and Flatfooted Individuals, Based on COP-Based Measures

Department of Industrial Engineering and Management, Yuan Ze University, Taoyuan, Chung-Li 32003, Taiwan
Department of Industrial Management, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
Author to whom correspondence should be addressed.
Received: 31 October 2016 / Accepted: 14 February 2017 / Published: 16 February 2017
(This article belongs to the Special Issue Multivariate Entropy Measures and Their Applications)
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Aging causes foot arches to collapse, possibly leading to foot deformities and falls. This paper proposes a set of measures involving an entropy-based method used for two groups of young adults with dissimilar foot arches to explore and quantize postural stability on a force plate in an upright position. Fifty-four healthy young adults aged 18–30 years participated in this study. These were categorized into two groups: normal (37 participants) and flatfooted (17 participants). We collected the center of pressure (COP) displacement trajectories of participants during upright standing, on a force plate, in a static position, with eyes open (EO), or eyes closed (EC). These nonstationary time-series signals were quantized using entropy-based measures and traditional measures used to assess postural stability, and the results obtained from these measures were compared. The appropriate combinations of entropy-based measures revealed that, with respect to postural stability, the two groups differed significantly (p < 0.05) under both EO and EC conditions. The traditional commonly-used COP-based measures only revealed differences under EO conditions. Entropy-based measures are thus suitable for examining differences in postural stability for flatfooted people, and may be used by clinicians after further refinement. View Full-Text
Keywords: center of pressure (COP); entropy; flatfoot; postural stability center of pressure (COP); entropy; flatfoot; postural stability

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Chao, T.-C.; Jiang, B.C. A Comparison of Postural Stability during Upright Standing between Normal and Flatfooted Individuals, Based on COP-Based Measures. Entropy 2017, 19, 76.

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