Antiphasic biarticular arm muscle activities reflects improved smoothness of motor performances in stroke patients

Concerningthe rehabilitation protocols for arm movements in stroke patients, many studies had conducted by executinga point-to-point movement. In general, the point-to-point reachingmovement was forward/backward or right/left direction exercise, whereas the circle-drawingtask needed to achieve these two directions simultaneously. From the viewpoint of the motor planning the circle-drawing movement would be useful as upper limb rehabilitation protocol. However, there is no evidence of restored antiphasic electromyographic (EMG) activities in biarticular arm muscles usingcircle-drawingtasks in a planar plane. The purpose of this study was to investigate whether or not the restored antiphasic EMG activities in biarticular arm muscles reflected improved smooth motor performances in stroke patients after 10 days of two-joint armmovement training. Three male sub-acute stroke patients, whose left arms were paralysis, performed point-topoint movement and circle-drawingtasks using haptic device system (Mitsubishi Precision Co., Ltd.) for upper limb neuromuscular rehabilitation. After the training, the movement velocity and achievement periods increased with the enhancement of the antiphasic EMG activities in biarticular arm muscles, whereas there was a decrease in the jerk after training for the same duration. These results suggested that stroke patients could achieve smooth motor performance with restoringthe antiphasic EMG activities in biarticular arm muscles by practicinga twojoint arm movement, especially, circle-drawing.