Fig. 4

Power spectra of the medial-lateral （M-L） direction （upper 4 graphs）, the anterior-posterior （A-P） direction （middle 4 graphs）, and vertical （VER） direction （lower 4 graphs）, for the same subjects as in Fig. 1 and 2. The abscissa represented frequency （Hz）. The ordinate represented power, and the dimension was all adjusted same as for all the directions.