EMG investigation of the effects of peripheral feedback on goal-directed wrist movements

The objective of this investigation was to determine whether timing of the wrist musculature could be altered when changing the goal of the movement or the sensory feedback needed to complete the movement. Electromyographic (EMG) data from seven wrist and finger muscles as well as simultaneous wrist and finger joint positions were recorded from five normal adults. Subjects performed wrist flexion and extension through different arcs of motion, as fast as possible against a physical stop, and as accurately as possible using visual feedback for speed and joint position. Next, the tonic vibratory reflex was elicited and topical anaesthetic spray was applied; no changes were observed afterwards. The subjects then repeated the wrist movements, and it was evident that activation of agonist and antagonist muscle groups varied according to the goal of the movement.