The Dynamics of Balance Control During Slipping

This study investigates experimentally the velocity of the center of mass with respect to the base of support while subjects step on slippery flooring. The moments of the joints of both legs are also investigated to gain further insights into the source of any correlation found in reacting to slippery perturbation. Twenty-two healthy subjects dressed with safety harness walked first without and then with slippery perturbation, guided by a metronome at 120 steps/min and 90 steps/min cadence. Data were collected from a motion analysis system and force plates. Subjects falling had distinguishably slower velocity of center of mass with respect to the lead stance foot compared to the subjects maintaining balance at contralateral toe off. Larger knee flexion moment and ankle plantar flexion moment in the perturbed leg were found among subjects regaining balance. Faster velocity of center of mass with respect to base of support is noteworthy in subjects regaining balance from slippery perturbation. The response of lower extremities, especially about the thigh and leg in the lead stance limb, were important to improve the velocity of the center of mass with respect to base of support.