Adaptation to knee flexion torque during gait

Studies have shown locomotor adaptation of the ankle to assistive torques, but the ability of the knee to adapt to assistive forces has not yet been explored. Understanding how humans modulate knee joint kinematics during gait could be valuable for designing assistive devices for stroke patients. In this study we examined how healthy subjects adapt to knee flexion torque assistance during gait. We hypothesized that 1) when given assistance subjects would adapt their locomotor patterns to walk with kinematics similar to baseline values and 2) removal of assistance following adaptation would result in substantially reduced knee flexion. Contrary to expectations, data from the five subjects show a weak adaptation and an increase in knee flexion kinematics after forces were removed. These results suggest that neuromuscular control of the knee joint during walking is not strongly modulated by feedforward mechanisms.