Lack of task-related motor unit activity in human triceps brachii muscle during elbow movements

Surface electromyographic (EMG) recordings have been associated with the acceleration and deceleration characteristics of single joint elbow movements [J. Neurophysiol., 63 (1990) 465-472]. To explore further the neural control of single joint movements, we investigated the behavior of motor units in triceps brachii muscle during elbow flexion and extension movements. In this communication, we provide evidence that individual motor units can contribute to each of the surface EMG bursts. This finding suggests that the nervous system can use the same motor units during movement regardless of whether the muscle is acting as an agonist or antagonist or functioning to initiate or terminate the movement.