TABLE 2.
Difference of CPX and resting HRV indicators between groups (M ± SD, N = 40).
| Variables | Group I (n = 26) | Group II (n = 14) | T | P |
| CPX | ||||
| VO2 max (ml/min/kg) | 26.232.67 | 25.503.01 | 0.79 | 0.44 |
| VCO2 (ml/min/kg) | 1,653.69239.46 | 1,627.29236.69 | 0.33 | 0.74 |
| AT (L/min) | 15.084.03 | 16.074.03 | −0.91 | 0.37 |
| VE (L/min) | 54.818.42 | 56.039.86 | −0.41 | 0.68 |
| Pre-HRV | ||||
| Pre-SDNN (ms) | 55.1515.46 | 48.2611.80 | 1.45 | 0.16 |
| Pre-RMSSD (ms) | 53.8516.54 | 53.1020.02 | 1.23 | 0.90 |
| Pre-LF (ms2) | 62.6212.10 | 63.0710.50 | −0.12 | 0.91 |
| Pre-HF (ms2) | 39.5411.15 | 38.4310.64 | 0.31 | 0.76 |
| Pre-LF/HF | 1.710.61 | 1.780.61 | −0.37 | 0.71 |
| Resting HR (beats/min) | 72.049.47 | 70.216.66 | 0.64 | 0.53 |
CPX, cardiopulmonary exercise test; Pre-HRV, heart rate variability indicators at resting before the exercise; VO2max, maximum oxygen uptake; VCO2, carbon dioxide ventilation; AT, anaerobic threshold; VE, ventilatory rate; SDNN, standard deviation of normal-to-normal interval; RMSSD, root mean square of the standard deviation; LF, low frequency (refers to 0.04–0.15 Hz); HF, high frequency (refers to 0.15–0.40 Hz); LF/HF, the ratio of low frequency to high frequency; HR, heart rate.