Antagonist EMG temporal patterns during rapid voluntary movement.

This study of 10 normal college-aged women was designed to clarify possible antagonist control mechanisms during the silent period of the agonist in rapid elbow extension tasks. Antagonist electromyographic temporal patterns were observed after agonist silence under various conditions to determine if antagonist activity in the rapid movement was controlled supraspinally (preprogrammed), spinally (reflexively), or by a combination of the two mechanisms. The subjects followed a velocity-controlled dot displayed on an oscilloscope. The antagonist latencies remained constant during intentionally and unintentionally terminated movements, but were altered by load conditions. This was seen as an automatic deceleration response, elucidating differences between antagonist control during ballistic and rapid movements.