The Acquisition Process of Movement accuracy and Smoothness in Tracking Task with Varying Acceleration

Abstract

Our purpose was to examine the kinematic and electrophysiological changes during elbow flexion and extension by tracking task acquisition with varying target acceleration. Task acquisition was assessed from the degree of movement error and movement acceleration profiles estimated using the surface electromyographic (EMG) activity and the muscle cocontraction index (CI). Subjects were divided into well-performing and poorly performing groups to compare task acquisition between the 2 groups. The results showed that the movement error decreased with an increase in the number of trials. Moreover, the EMG activity changes differed between the 2 groups. The movement acceleration profiles also appeared similar to the target wave (single peak acceleration). The correlation coefficient between target and movement acceleration increased with the progress of acquisition, indicating acquisition of movement smoothness. EMG activities were regulated by task acquisition, and the pattern of EMG changes depended on the performance level. The CI was lower in the well-performing group than in the poorly performing group, showing difference in muscle activity regulation between the 2 groups. In conclusion, movement error, muscle activity (including CI), and correlation coefficient between target and movement acceleration can be used to evaluate movement smoothness and muscle activity regulation by tracking task acquisition with varying target acceleration.