The motor control and muscle activities during the voluntary rhythmic movement task

为了了解站立时的运动控制，本研究采用力平台视觉引导跟踪任务对健康青年和老年人的下肢运动表现和肌肉活动进行了研究。运动任务的运动方向、运动幅度和运动速度对运动性能有影响。特别是运动表现与运动速度呈U型关系，两组均表现出完成运动任务的最佳运动速度。膝关节屈肌是双关节肌，其肌肉活动的年龄差异得到证实。这表明双关节肌肉的功能丧失可能会随着年龄的增长而缩小老年人对体位策略的选择范围。

To understand the motor control during standing, this study investigated the motor performance and muscle activities of lower limbs in healthy youths and elders by using the visually guided tracking task on the force platform. The motor performance was influenced by the movement direction, the amplitude and the velocity of the motor task. Especially, there was the U shape relation between the motor performance and the motor velocity, and the optimum motor velocity for the motor task was shown in both groups. Age differences were confirmed in muscle activities of knee flexors which were biarticular muscles. This suggested that the functional loss of biarticular muscles might narrow elder's range of choice for the postural strategy by aging.