A subject-specific postural instability parameter

A mathematical modeling approach is applied for deriving subject-specific stabilometric parameters associated with center-of-pressure sway measurements for assessing balancing ability of subjects in quiet standing on a force platform. Based on the inverted pendulum model, a new combined stabilometric parameter including anthropometric characteristics (body height and mass) is obtained which represents a measure of postural instability. A physical meaning of the subject-specific parameter is related to the effective stiffness of the inverted pendulum model.