Time Course of Change in Movement Structure During Learning of Goal-Directed Movement

Primary and secondary submovements are important in human movements. The purpose of this study was to examine the time course of changes in kinematics and electromyography (EMG) parameters for primary and secondary submovements associated with the learning of a goal-directed aiming movement task. The subjects comprised 9 neurologically normal adults. They were instructed to make horizontal planar movements of elbow flexion that were both fast and accurate. The learning session comprised 20 blocks of 10 movements. Our research found that the kinematics- and EMG-related parameters of the antagonistic triceps brachii muscle gradually changed over the course of the learning period and reached a plateau that fitted an exponential function. However, the EMG parameters of the agonistic biceps brachii muscle did not markedly change. Moreover, the kinematics- and EMG-related parameters for the primary and secondary submovements varied at different rates during the motor learning. Our findings may facilitate the understanding of the learning of a goal-directed aiming movement in sports and rehabilitation settings.