SMOOTHNESS USING ANGULAR JERK COST OF THE KNEE JOINT MOVEMENT AFTER A REDUCTION IN WALKING SPEED

摘要

The angular jerk cost (AJC) was proposed to objectively represent the smoothness of joint movement by calculating the time-dependent changes in acceleration during motion. There are currently no reports focusing on smoothness using AJC measurements of the knee joint movement during the stance phase of gait. The purpose of this study was to verify whether a reduced walking speed affects the smoothness of the knee joint movement during the stance phase of gait. The gaits of 12 healthy adults were assessed. A slower walker showed a significant reduction in the AJC value in the period between the initial contact and the loading response, as compared with someone walking at a comfortable speed.The maximum ground reaction force of the stance phase at a comfortable walking speed was significantly larger than that at a slower walking speed. Thus, although the smoothness of the knee joint was impaired by a rapid load in the early stance phase, a slower walking speed reduced the ground reaction force and angular acceleration of the knee joint and created a smoother movement. The AJC can be an important index for understanding the smoothness of the knee joint in the early stance phase.