The dynamics of balance control during slipping

This study investigates experimentally the velocity of the center of mass w ith 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 furt her insights into the source of any correlation found in reacting to slippe ry perturbation. Twenty-two healthy subjects dressed with safety harness wa lked first without and then with slippery perturbation, guided by a metrono me at 120 steps/min and 90 steps/min cadence. Data were collected from a mo tion analysis system and force plates. Subjects falling had distinguishably slower velocity of center of mass with respect to the lead stance foot com pared to the subjects maintaining balance at contralateral toe off. Larger knee flexion moment and ankle plantar flexion moment in the perturbed leg w ere found among subjects regaining balance. Faster velocity of center of ma ss with respect to base of support is noteworthy in subjects regaining bala nce from slippery perturbation. The response of fewer extremities, especial ly about the thigh and leg in the lead stance limb, were important to impro ve the velocity of the center of mass with respect to base of support.