Effects of Aerobic Exercise on Heart Rate Variability (HRV)

Background: This study was conducted to find out the difference of heart rate variability between practicing Tai Chi and walking at 6 km/hr. Methods: Twelve healthy volunteers aged 25 to 35 were recruited through advertisement. All the subjects gave their informed consent, and the study was approved by the Institutional Review Board of the Catholic Medical Center Research Foundation. The subjects either practised Tai Chi or walked at 6 km/hr on a treadmill machine, maintaining 5-minute rest, 20-minute exercise, and 30-minute rest. After 1 week, they switched and performed the other form of exercise. During the exercise, beat-to-beat HRV data was recorded by Polar S-810. We calculated HRV indices using Matlab software program and analyzed the mean value of HRV indices. Results: The differences of the mean value of HRV indices of pre-exercise resting period were not significant. However, repeated ANOVA revealed that there were significant differences of change in the mean of SDNN (-14.27 +/- 13.03 ms, -33.67 +/- 20.23 ms; P=0.023), RMSSD (-10.17 +/- 9.59 ms, -21.90 +/- 12.60 ms; P=0.087), and STIDX (171.60 +/- 196.84, 1003.49 +/- 812.56; P=0.003) between practising Tai Chi and walking. The differences of change in mean heat rate, LF/HF ratio, LF, HF and TP were not significant. The differences of the mean value of HRV indices of the post-exercise resting period were not significant compared to the pre-exercise period. The result of this study suggest that exertional intensity of practising Tai Chi is similar to that of walking. Moreover, practising Tai Chi may be more profitable than walking in the aspect of HRV.