기저면의 크기 변화가 직립 자세제어의 가변성과 복잡성에 미치는 영향

Abstract

The aim of the study was to investigate the effect of base of support on standing postural control. In this study, we measured 24 persons’ COP signals from 20 % to 100% base of support. For the variability measures, mean velocity(MV), root mean square(RMS), sway path (SP), 95% ellipse area were measured for each direction and radial movement. For the frequency domain parameters four well-known quantitative parameters were used: the median frequency, 50, 80, and 90 percentile power spectrum density. As nonlinear dynamic measures, approximate entropy(ApEn), sample entropy(SampEn) and detrended fluctuation analysis(DFA) a. The results showed that only variability measures linearly and significantly increased as base of support decreased (p<.001). However, frequency domain parameters and nonlinear measures drastically change only when base of support reduced up to 20%. Results implied that even though base of support reduced, it did not directly change the postural control strategy. There are some thresholds to change the control process. Therefore, we conclude that persons’s postural control system compensate the reduced the base of support. It is effective until 20-40%.