Experimental foundations of EMG biofeedback with the upper extremity: a review of the literature.

This article reviews the experimental foundations of EMG biofeedback with the upper extremity. Considered are investigations on recruitment and training of single and multiple motor units in both normal and nonnormal subjects, on transfer of training effects from trained to untrained muscles, and on the relationship of reduced muscle output to relaxation. Examined are procedures, results, and conclusions of these basic studies. Problems noted in the research are discussed and suggestions are made for further work in the area.