The effect of transcutaneous median nerve stimulation on heart rate variability in healthy young adults

Background: As low heart rate variability (HRV) has been shown to be associated with cardiovascular diseases (CVDs), attempts have been made to increase HRV through a variety of methods. It has recently been suggested that HRV might be increased by nerve stimulation. The aim of this study was to investigate the effect of transcutaneous median nerve stimulation (MNS) on HRV on healthy human subjects with low HRV. Methods: This is a double-blind randomized control trial. Sixty-one healthy adults, male and female, were recruited to the study. Among the 61 participants, only 38 participants with lower than 40 standard deviation of NN interval (SDNN), mean age 49.5±6.8 years, were selected to further participate in the study. Participants underwent two sessions of either MNS (5 Hz, 100–300 μs for 20 minutes) or a sham treatment (control). Their HRV measurements were compared before, immediately after treatment, and then again 10 minutes later. Results: SDNN increased following both treatments, yet there were no effects on other HRV variables, blood pressure (BP), or resting heart rate (HR) (P>0.05). Conclusions: Transcutaneous stimulation of the left median nerve on healthy subjects, as applied in the present study, was safe and tolerable, and SDNN was increased on healthy subjects with low HRV.