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.

Conclusion : 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.

Background
: This study was conducted to find out the relationship between autonomous function and fatigue rating. The subjects were patients with complaints of fatigue who visited the department of family medicine in a general hospital.

Methods : We conducted this study from April to December 2002 in patients complaining of fatigue. The subjects were categorized into low, intermediate, and high fatigue groups. Heart rate variability was measured for five minutes at rest, followed by a five minute mental arithmetic test. We analyzed the relationship between fatigue ratings and autonomous function with SPSS 10.0.

Results : There was a statistically significant increase in the mean heart rate variability in the all three groups at rest and with stress. There was a statistically significant increase in LF norm increase in the low and high fatigue groups. HF norm showed a statistically significant decrease in the intermediate and high fatigue group. The variation in LF norms was highest in the low fatigue group and lowest. With the mental arithmetic test, the low fatigue group showed decreased rMSSD, HF and HF norm values compared to the intermediate group. The above values showed decrease in the high fatigue group compared to the low group.

Conclusion : Overactivity of the sympathetic nervous system was observed as fatigue ratings increased. The cadiovascular autonomic response tended to decrease as fatigue ratings increased.