Effects of tactile and thermal stimulation on heart rate and its autonomic neuronal mechanisms in healthy young women

Abstract

We investigated the effects of tactile (stroking) and thermal stimulation of the back on heart rate and its autonomic mechanism in healthy young women in a prone position. Three stimuli were added at random: 1) stroking over a towel, 2) stroking over a heated towel (thermal + stroking), and 3) putting a towel on the back without stroking. During stroking stimulation, the heart rate and sympathetic activity indices of low-frequency (LF)/high-frequency (HF) and LFnu decreased, and the parasympathetic activity index HFnu increased. Thermal + stroking stimulation prolonged these effects. Although the same effect was also observed after putting a towel on the back without stroking, the duration of the effects was shorter than that of the stroking stimulation. No effect was observed in the control experiment. The score on the relaxation index significantly increased after stroking stimulation, and the score was even higher when thermal + stroking stimulation was delivered. The above findings suggest that heart rate decreases through changes in both the sympathetic and parasympathetic nerve activities due to mechanical and thermal stimulations to the back. It appears that the psychological relaxation was also partially involved in the decrease of heart rate.