Heart rate and finger pulse amplitude during muscular relaxation with frontalis versus forearm EMG feedback.

Twenty-nine volunteers participated in a one-session experiment consisting of 10 min rest followed by a 30 min treatment period. Brief relaxation instructions were given at the beginning of the rest period. The treatment was either frontalis EMG feedback, forearm EMG feedback, or non-contingent stimulation. The two feedback groups showed EMG decreases in their respective target muscles during the no-feedback rest period, with no further decrease during feedback training, indicating that feedback was no more effective than relaxation instructions. Heart rate decreased significantly in both feedback groups. Finger pulse amplitude decreased significantly in the forearm feedback group. It is pointed out that the latter change does not necessarily indicate peripheral vasoconstriction, but may be due to a fall in pulse pressure as a consequence of increased blood flow to the relaxing muscles. The results are unsupportive of the assumption that frontalis relaxation is particularly effective in inducing a generalized relaxation.