Abstract
BACKGROUND: The purpose of the present study was to investigate the effects of bradycardia induced by pre-exercise acupuncture on heart rate responses during short-duration exercise. METHODS: A total of 29 healthy subjects underwent two protocols: protocol 1 assessed the effects of manual acupuncture on heart rate response during rest, and protocol 2 tested the hypothesis that the bradycardic effects induced by pre-exercise acupuncture continue during low- and high-intensity exercise. Their average age, height, weight, and body mass index were 21.2 ± 2.0 years, 167.2 ± 8.8 cm, 63.8 ± 12.8 kg, and 22.7 ± 3.5 kg/m(2), respectively. In acupuncture stimulations for protocols 1 and 2, an acupuncture needle was inserted into the lower leg and manual acupuncture stimulation was performed at 1 Hz. RESULTS: In protocol 1 (resting condition), acupuncture stimulation induced a bradycardic response, which continued for 4 min after the cessation of acupuncture stimulation (p < 0.05). In protocol 2, the bradycardic response induced by pre-exercise acupuncture stimulation remained during low-intensity exercise and in the beginning of high-intensity exercise performed immediately after the cessation of acupuncture stimulation (p < 0.05). However, the effects disappeared when post-acupuncture exercise was performed when the heart rate was approximately 140 beats/min during high-intensity exercise. The rating of perceived exertion after exercise differed significantly between the acupuncture stimulation task (7.9 ± 1.6) and no-stimulation task (8.5 ± 2.0) (p = 0.03) only in the low intensity group. CONCLUSION: This study may provide new insights into the effect of acupuncture stimulation on psycho-physiological conditions during exercise.