Effects of Acupuncture Sensations on Transient Heart Rate Reduction and Autonomic Nervous System Function During Acupuncture Stimulation

Objective: During acupuncture stimulation, heart rate (HR) transiently decreases and autonomic nervous system (ANS) function becomes parasympathetic-dominant. To clarify the effect of acupuncture sensations (pain, De Qi), the effects of deep acupuncture sensations on HR and ANS functions were determined. Materials and Methods: In this comparative study at Teikyo Heisei University, Tokyo, Japan, 40 healthy, male student volunteers rested for 20 minutes before undergoing manual acupuncture to the Shousanli (LI 10) acupoint on the left forearm for 2 minutes at a frequency of 1 Hz, with concurrent electrocardiography. Depth of stimulation was 15-20 mm. These subjects described their subjective acupuncture sensations. Calculations were performed, using HR variability analysis to find HR and low-frequency (LF) normalized units (nu), the ratio of LF components to total components (as an index of sympathetic nervous system function), high-frequency (HF)nu, the ratio of HF components to total components (as an index of parasympathetic nervous system function), and LF/HF (as an index of sympathetic and parasympathetic balance). Results: For the final analysis, data were available for 32 subjects. Compared to before acupuncture, HR decreased during acupuncture. HR decreased when no acupuncture sensations or when weak De Qi sensations were perceived, and remained unchanged when acupuncture sensations without De Qi or strong De Qi were perceived. LFnu decreased, HFnu increased, and LF/HF decreased, regardless of pain or De Qi. Conclusions: Acupuncture stimulation reduced HR even without De Qi sensations and caused ANS function to be parasympathetic-dominant, irrespective of the perception of acupuncture sensations.