Covert neuromuscular activity of the dominant forearm during visualization of a motor task.

This study evaluated specific covert neuromuscular activity during a silent visualization exercise. 30 subjects participated in a dual-baseline single-subject procedure. The experimental test condition required the subjects to visualize themselves squeezing a hand-size rubber ball as tightly as possible for 1 min. In the comparison test condition, subjects were asked to imagine the 'sun setting on the horizon' for 1 min. Visualization of the motor task brought about significant (p <.05) increases in dominant forearm EMG (microV) and heart-rate activity (bpm) from rest to the experimental test condition. Nondominant forearm activity showed no significant changes from rest to either test condition, and heart-rate activity (bpm) showed no significant change from rest to the comparison visualization task.