歩行中の下肢関節間シナジーにおける足関節の寄与

抄録

Some previous studies about human walking have suggested that the variance of the toe position relative to the hip position is suppressed by joint synergy which is a compensatory inter-joint coordination, especially during double support phase and at the moment of the minimum toe clearance. However, the ankle position would also be an important variable to be controlled around the end of swing phase just before heel strike against the ground. We hypothesized that the leg joint synergy changes according to the stage in a gait cycle in order to switch the variable to be controlled, i.e., from the toe position in some stages to the ankle position in the others, and investigated the validity of this hypothesis by analyzing gait kinematics. Hip, knee, ankle, and toe trajectories of eight adult subjects were recorded during level walking by a motion capture system by 200fps. The uncontrolled manifold analysis was applied to quantify the joint synergy. The results showed that the leg joint synergy worked so as to adjust the toe position relative to the hip position from the second double support phase to the middle of the swing phase, i.e., from the push-off phase to the moment of the minimum toe clearance, and the ankle joint was strongly involved in the formation of the synergy during these periods. Contrary, the joint synergy worked so as to adjust the ankle position rather than the toe position in the end of the swing phase. These results suggest that the toe or ankle position is selected as a controlled variable according to the distance from the ground during walking and the switching of the joint synergy occurs so as to stabilize the controlled variable.