Agonist and Antagonist Muscle EMG Activity Pattern Changes with Skill Acquisition

Abstract

The purpose of this research was to investigate the modifications in the control of the biceps brachii (agonist) and triceps brachii (antagonist) muscles during the learning of two elbow flexion tasks in sixteen college-age women. A positioning and a coincidence task were each performed at 40° and 200° per second angular velocity while bipolar surface electrodes recorded the electromyographic (EMG) activity of the muscles involved. Data on the EMG activity, angular kinematics, and timing and angular displacement error were quantified and subjected to statistical analyses. The results of the error analyses indicated that subjects did learn the various tasks over the 120 trials. Because there were no significant changes in the angular velocity patterns over trials, the EMG activity modifications are suggested to reflect differences in the control of the muscles monitored during the movements. In addition, EMG activity pattern modifications which occurred in discrete portions of the movements in both muscles indicate an increased cocontraction of the opposing muscles as subjects learned the tasks. Temporal periods in which modifications were observed appear to represent the critical periods in each movement task.

Key Words:

• motor learning
• motor control
• electromyography
• muscles
• skill acquisition