CONTROL OF WHOLE-BODY BALANCE IN THE FRONTAL PLANE DURING HUMAN WALKING

A whole-body inverted pendulum model was used to investigate the contr ol of balance and posture in the frontal plane during human walking. T he model assessed the effects of net joint moments, joint acceleration s and gravitational forces acting about the supporting foot and hip. T hree video cameras and two force platforms were used to collect kinema tic and kinetic data from repeat trials on four subjects during natura l walking. An inverse solution was used to calculate net joint moments and powers. Whole body balance was ensured by the centre of mass (CM) passing medial to the supporting foot, thus creating a continual stat e of dynamic imbalance towards the centreline of the plane of progress ion. The medial acceleration of the CM was primarily generated by a gr avitational moment about the supporting foot, whose magnitude was esta blished at initial contact by the lateral placement of the new support ing foot relative to the horizontal location of the CM. Balance of the trunk and swing leg about the supporting hip was maintained by an act ive hip abduction moment, which recognized the contribution of the pas sive accelerational moment, and countered a large destabilizing gravit ational moment. Posture of the upper trunk was regulated by the spinal lateral flexors. Interactions between the supporting foot and hip mus culature to permit variability in strategies used to maintain balance were identified. Possible control strategies and muscle activation syn ergies are discussed.