Improved Sympathetic Activity With Short-Term Effects of Yoga in Young Adults.

The purpose of this study was to clarify the heart rate variability (HRV) transition after a single yoga program. Participants were 22 females who were healthy university students and had never practiced yoga before. They practiced yoga while recording their HRV. Heart rate (HR), high frequency (HF; 0.15-0.4 Hz) as parasympathetic and low frequency (LF; 0.04-0.15 Hz) components were extracted, and then the LF/HF ratio as sympathetic and normalized units of HF HFnu = HF/(LF + HF) as parasympathetic modulation in autonomic activity were calculated. HR and HRV indices after yoga were divided into four 5-minute periods (after 5, 10, 15, and 20 minutes) and compared before yoga. HR and LF/HF at all periods after yoga were significantly lower than before yoga (P < .01, all). HF after yoga was not significantly changed, but HFnu after 5, 10, and 15 minutes was significantly higher than before yoga (P < .01, <.01, and =.02, respectively). The short-term effects of yoga on HRV implied a decrease in sympathetic modulation and a relative increase in parasympathetic modulation. Therefore, yoga may be used as a fast-acting alternative therapy to significantly improve sympathetic activity.