Table 3. Comparison of CPET parameters between mMRC grades <2 and ≥2.
| CPET parameters | mMRC grade <2 | mMRC grade ≥2 | P value |
|---|---|---|---|
| Age, years | 68.3±7.8 | 68.0±15.0 | 0.895 |
| VO2 max, L/min | 1.15±0.32 | 0.81±0.30 | <0.001 |
| VO2 max, mL/kg/min | 17.4±4.6 | 12.9±4.19 | <0.001 |
| AT, L/min | 0.69±0.23 | 0.57±0.29 | 0.028 |
| AT, % predicted VO2 max | 40.5±13.3 | 36.2±17.1 | 0.163 |
| WR max, W | 91.8±26.6 | 58.1±26.7 | <0.001 |
| HR max, beats/min | 135.5±20.8 | 124.0±13.3 | 0.001 |
| HRR, beats/min | 24.0±18.0 | 34.8±12.8 | 0.004 |
| O2 pulse max, mL/beat | 9.15±5.12 | 6.77±2.63 | 0.024 |
| O2 pulse max, % predicted | 82.1±24.0 | 69.0±26.7 | 0.011 |
| Systolic BP max, mmHg | 201.3±32.2 | 196.8±36.0 | 0.515 |
| VE max, L/min | 53.1±14.7 | 39.4±14.7 | <0.001 |
| MVV, L/min | 84.9±23.8 | 57.2±21.0 | <0.001 |
| Peak PETCO2, mmHg | 37.1±4.9 | 34.3±6.6 | 0.012 |
| Breathing reserve, % | 34.7±18.1 | 29.3±15.5 | 0.120 |
| VD/VT at rest | 0.38±0.07 | 0.39±0.05 | 0.483 |
| VD/VT peak | 0.23±0.04 | 0.27±0.06 | 0.006 |
Data are presented as mean ± standard deviation. CPET, cardiopulmonary exercise testing; mMRC, modified Medical Research Council; VO2 max, maximal oxygen uptake; AT, anaerobic threshold; WR, work rate; HR, heart rate; HRR, heart rate reserve; BP, blood pressure; SpO2, saturation of percutaneous oxygen; VE, minute ventilation; MVV, maximal voluntary ventilation; PETCO2, end-tidal PCO2; VD, dead space volume; VT, tidal volume.