Modelling of the biomechanics of posture and balance

A technique for studying the relationship of posture to balance has been developed. To investigate this relationship quantitatively, the human body was treated as consisting of 11 rigid body segments, each with six degrees of freedom. A bilateral Selspot II/TRACK data acquisition system provides position and orientation kinematic data for estimation of the trajectories of the individual body segment centers of gravity. From these, the whole body center of gravity is estimated and compared to concurrent force plate center of force data. Center of gravity and center of force excursions agree where dynamics are not significant. The technique may be employed to study quiet stance, response to postural disturbances, or the initiation and coordination of complex movements such as gait.