What insights can be gained when analysing the resultant centre of pressure trajectory?

This article reviews the main aspects of the interpretation of centre of pressure trajectories measured from a force platform during undisturbed upright stance control. This objective measure has been used for more than 40 years by both clinicians and fundamental scientists to assess the postural stability of both healthy and disabled individuals. Besides rough summary statistics, which provide global information on the position of the body relative to the base of support, various techniques have been proposed such as frequency analysis, fractional Brownian motion modelling, and chaos systems, to give more relevant insights from neurophysiological and biomechanical points of view. Concurrently, the contribution of the joints and muscles of the lower legs has been studied trough EMG measures as well as indices computed from data from separate measures under each foot.