Table 2.
Exercise responses at the VT/V̇e inflection and at maximal exercise
| Mild CF |
Controls |
|||
|---|---|---|---|---|
| VT/V̇e inflection | Maximum | VT/V̇e inflection | Maximum | |
| Work rate, W | 122 ± 44* | 166 ± 57* | 192 ± 61 | 235 ± 74 |
| Work rate, %predicted | 63 ± 18* | 85 ± 24* | 86 ± 18 | 108 ± 22 |
| V̇o2, ml/kg/min | 29 ± 6* | 38 ± 8* | 40 ± 11 | 47 ± 12 |
| V̇o2, l/min | 2.05 ± 0.63* | 2.68 ± 0.82* | 3.00 ± 0.89 | 3.47 ± 1.05 |
| V̇o2, % predicted | 78 ± 17* | 102 ± 22* | 101 ± 17 | 119 ± 21 |
| V̇co2, l/min | 2.14 ± 0.66* | 2.92 ± 0.85* | 3.05 ± 0.86 | 3.75 ± 1.04 |
| RER | 1.06 ± 0.08 | 1.10 ± 0.07 | 1.02 ± 0.06 | 1.09 ± 0.06 |
| V̇e, l/min | 65 ± 21* | 95 ± 27* | 88 ± 24 | 125 ± 40 |
| VT, l | 2.34 ± 0.63 | 2.32 ± 0.51† | 2.76 ± 0.78 | 2.72 ± 0.70 |
| Fb, breaths/min | 28 ± 7† | 41 ± 9 | 33 ± 6 | 46 ± 8 |
| V̇e/V̇co2 | 30 ± 4 | 33 ± 4 | 29 ± 2 | 33 ± 3 |
| V̇e/V̇o2 | 32 ± 6 | 36 ± 6 | 30 ± 3 | 36 ± 3 |
| PetCO2, mmHg | 38 ± 6 | 35 ± 5 | 39 ± 2 | 35 ± 3 |
| Estimated VD/VT | 0.14 ± 0.05* | 0.14 ± 0.04* | 0.10 ± 0.05 | 0.11 ± 0.05 |
| ΔIC, l | 0.17 ± 0.43* | 0.02 ± 0.38* | 0.58 ± 0.35 | 0.39 ± 0.38 |
| EELV, %TLC | 49 ± 8 | 51 ± 8 | 46 ± 6 | 49 ± 5 |
| EILV, %TLC | 87 ± 5 | 89 ± 6 | 87 ± 6 | 90 ± 4 |
| IRV, l | 0.80 ± 0.36 | 0.67 ± 0.39 | 0.86 ± 0.36 | 0.66 ± 0.29 |
| VT/IC, % | 75 ± 9 | 78 ± 10 | 75 ± 11 | 80 ± 9 |
| V̇e/MVV, % | 48 ± 12 | 71 ± 14 | 55 ± 11 | 77 ± 12 |
| HR, beats/min | 154 ± 14* | 176 ± 11* | 167 ± 13 | 183 ± 9 |
| HR, %predicted | 81 ± 7* | 92 ± 6* | 87 ± 6 | 96 ± 4 |
| O2 Pulse, ml/beat | 13 ± 4* | 15 ± 4* | 18 ± 5 | 19 ± 6 |
| O2 Pulse, %predicted | 97 ± 18* | 110 ± 22† | 115 ± 20 | 124 ± 22 |
| SpO2, % | 97 ± 1 | 97 ± 1 | 97 ± 2 | 96 ± 4 |
| Breathing discomfort, Borg scale | 2.7 ± 2.0* | 6.0 ± 2.7 | 4.3 ± 2.7 | 7.1 ± 2.6 |
| Leg discomfort, Borg scale | 4.1 ± 2.6 | 8.1 ± 2.3 | 5.3 ± 2.3 | 8.5 ± 2.0 |
V̇o2, oxygen consumption; V̇co2, carbon dioxide production; RER, respiratory exchange ratio; V̇e, minute ventilation; VT, tidal volume; Fb, breathing frequency V̇e/V̇co2, ventilatory equivalent for carbon dioxide; V̇e/V̇o2, ventilatory equivalent for oxygen; PetCO2, partial pressure of end tidal carbon dioxide; VD/VT, dead space to tidal volume ratio; ΔIC, change in inspiratory capacity from rest; EELV, end-expiratory lung volume; EILV, end-inspiratory lung volume; TLC, total lung capacity; IRV, inspiratory reserve volume; MVV, maximal voluntary ventilation; HR, heart rate; SpO2, arterial oxygen saturation via pulse oximetry. Values are means ± SD,
Significantly different from control subjects, P < 0.05;
P = 0.05.