Fig. 3

Example of the experimentally obtained center of pressure (COP) fluctuations during: a Unsupported quiet sitting and b FES-assisted quiet sitting for one participant. AP represents anterior-posterior and ML medial-lateral sway direction. The planar representations (left) show spatial fluctuations of the combined AP and ML sway. Time series plots (right) show the corresponding AP and ML postural sway time series separately. Note that only a representative 15 s of data is shown to describe the postural sway behaviour