Non-linear analysis of human stability during static posture

The goal of this paper is to analyze the human stability in the upright position. This is achieved by analyzing the visual input, feet placement, and age affects on the human body equilibrium using stabilometric signals. Twenty eight healthy subjects (14 young and 14 elderly subjects) participated to this study to collect their stabilometric signals under four conditions. Three non linear methods are used: time reversibility, sample Entropy and Lyapunov exponents methods. Lyapunov exponents show the best results especially between feet apart and feet together condition and between young and elderly subjects with significant differences. ROC analysis and Anova test were used and the results show significant differences between groups with p-values less than 0.001.