Selected parameters at peak exercise
| Healthy (n=11) | Mild–mod COPD (n=8) | Severe COPD (n=11) | |
|---|---|---|---|
| Stopped 2° breathing; n (%) | 2 (18) | 5 (63) | 10 (91) |
| Dyspnoea Borg (×/10) | 3 (1–5) | 4 (2–5) | 4 (3–5) |
| Load (W) | 133 (15) | 82 (13)* | 44 (8)** |
| VO2 (L/min) | 1.85 (0.19) | 1.31 (0.14)* | 0.83 (0.15)** |
| VO2 (mL/min/kg) | 24.6 (1.8) | 15.9 (1.7)** | 12.0 (0.4)** |
| VO2% predicted | 100 (6) | 77 (5)* | 49 (4)**†† |
| HR (b/m) | 147 (7) | 131 (7) | 107 (4)**† |
| HR reserve (%) | 8 (5) | 18 (4) | 33 (3)**† |
| VE (L/min) | 66 (10) | 46 (6) | 28 (2)** |
| BR (%) | 49 (5) | 41 (3) | 16 (6)**†† |
| SpO2 (%) | 98 (0) | 98 (1) | 94 (1)**†† |
| VT (L) | 2.15 (0.24) | 1.56 (0.22) | 1.11 (0.08)** |
| TI/TTot | 0.45 (0.07) | 0.41 (0.02)* | 0.36 (0.01)**† |
| IC (L) | 3.44 (0.27) | 2.52 (0.28)* | 1.99 (0.15)** |
| Delta IC (%IC rest) | −0.35 (2.90) | 12.10 (3.54) | 15.26 (4.08)** |
| DHI | −0.01 (0.06) | 0.46 (0.18) | 0.96 (0.27)** |
Data shown as mean (SEM) or median (range). *p<0.05, **p<0.01 from healthy, †p<0.05, ††p<0.01 from mild–mod COPD. Operational lung volume data available in 7 patients with mild–moderate COPD and 10 patients with severe COPD.
BR, breathing reserve; DHI, dynamic hyperinflation index; HR, heart rate; IC, inspiratory capacity; SpO2, peripheral oxygen saturation; TI/TTOT, respiratory duty cycle; VE, minute ventilation; VO2, oxygen consumption; VT, tidal volume.