身体重心動揺の推定と外周面積・総軌跡長の新しい解釈

We devised a method for evaluating the sway of the center of pressure (COP) in stabilometry. Data from 365 healthy adults without dizziness and 2 patients with vestibular disorders were examined. For each subject, the COP was recorded with 100 Hz sampling for 60 seconds under the eyes open and eyes closed conditions while standing upright with the inner sides of both feet in contact. We separated the COP data into the sway of the center of gravity (COG) component and the sway control component. For this purpose, the DFT (discrete Fourier transform) and its inverse transformation were applied to sampled data. Using this method, the COP data were separated into frequency bands up to and including 0.4 Hz and frequencies above 0.4 Hz. Considering the former as the body’s center of gravity sway (COG) component and the latter as the sway control component, we created XY diagrams for each. We calculated the enveloped area, total length, and Romberg’s ratio of the XY diagram, and examined the characteristics and age-related changes in these data. The COP Romberg ratio of patients with vestibular disorders did not necessarily match with the COG component and/or the sway control component. We consider that this finding could be useful to evaluate the state of diseases such as central vestibular compensation.