The Concept Of Metastability For One-Legged Standing

Standing on one foot has been characterized by a continuum between static equilibrium (standing) and dynamic equilibrium (walking). This suggests that sways of the body are important for a person to maintain the upright position and prevent a fall. We examine the center of pressure (COP) changes with and without visual input, and find that the character of the COP dynamics is different on different timescales; it is random (stochastic) on short timescales ($0< t< 20 \, \mbox{ms}$), ballistic (deterministic) on intermediate timescales ($20 \, \mbox{ms} < t < 200 \, \mbox{ms}$), and random on long timescales.