Table 3.
Hemodynamic, Gas Exchange, and Blood Gas Variables During Normoxic Incremental Exercise on Day 1 and 15 (n = 8)
| Stationary (0 W) | Stage 2 (97 ± 2 W) | Stage 4 (171 ± 5 W) | Peak (D1/D15: 268 ± 17/253 ± 17 W) | ||
|---|---|---|---|---|---|
| Hemodynamic variables | |||||
| Heart rate, beats·min−1 (**) | D1 | 88 ± 5 | 120 ± 5 | 151 ± 5 | 176 ± 2 |
| D15 | 85 ± 6 | 125 ± 5 | 156 ± 5 | 174 ± 3 | |
| Mean arterial pressure, mmHg (**) | D1 | 95 ± 3 | 115 ± 10 | 118 ± 3 | 132 ± 3 |
| D15 | 95 ± 5 | 109 ± 5 | 122 ± 4 | 130 ± 3 | |
| Cardiac output, l·min−1 (**) | D1 | 8.7 ± 0.6 | 15.3 ± 0.6 | 19.4 ± 0.8 | 25.3 ± 1.5 |
| D15 | 9.2 ± 0.7 | 16.4 ± 0.8 | 19.8 ± 1.0 | 23.2 ± 1.8 | |
| Gas exchange variables | |||||
| Oxygen consumption, l·min−1 (**, *,†) | D1 | 481 ± 67 | 1,672 ± 90 | 2,619 ± 112 | 3,622 ± 194 |
| D15 | 452 ± 46 | 1,675 ± 86 | 2,583 ± 99 | 3,260 ± 185† | |
| Carbon dioxide production, l·min−1 (**, *,†) | D1 | 491 ± 68 | 1,419 ± 86 | 2,475 ± 137 | 3,965 ± 221 |
| D15 | 443 ± 50 | 1,366 ± 101 | 2,574 ± 163 | 3,534 ± 167† | |
| Ventilation, l·min−1 (**) | D1 | 23 ± 4 | 44 ± 3 | 71 ± 5 | 138 ± 12 |
| D15 | 23 ± 4 | 46 ± 4 | 84 ± 9 | 132 ± 8 | |
| RER (**) | D1 | 1.04 ± 0.07 | 0.85 ± 0.03 | 0.94 ± 0.02 | 1.10 ± 0.02 |
| D15 | 0.98 ± 0.07 | 0.82 ± 0.04 | 1.00 ± 0.04 | 1.10 ± 0.02 | |
| Ventilatory equivalent for oxygen uptake (**) | D1 | 52 ± 7 | 27 ± 2 | 27 ± 1 | 38 ± 3 |
| D15 | 51 ± 5 | 28 ± 2 | 32 ± 3 | 41 ± 3 | |
| Ventilatory equivalent for carbon dioxide production (**,††) | D1 | 48 ± 3 | 31 ± 1 | 28 ± 1 | 35 ± 2 |
| D15 | 52 ± 2† | 33 ± 1 | 33 ± 2† | 37 ± 2† | |
| Alveolar oxygen partial pressure, mmHg (**,††) | D1 | 112 ± 3 | 100 ± 2 | 105 ± 2 | 115 ± 2 |
| D15 | 113 ± 4 | 101 ± 3 | 109 ± 3† | 121 ± 2† | |
| Alveolar-to-arterial oxygen difference, mmHg (**) | D1 | 8 ± 2 | 10 ± 3 | 16 ± 2 | 27 ± 5 |
| D15 | 10 ± 2 | 10 ± 2 | 18 ± 2 | 25 ± 3 | |
| Blood gas variables | |||||
| Arterial oxygen saturation, % (**,††) | D1 | 96.8 ± 0.2 | 95.9 ± 0.4 | 95.5 ± 0.3 | 93.9 ± 0.7 |
| D15 | 97.2 ± 0.2 | 96.6 ± 0.3† | 96.1 ± 0.4† | 95.8 ± 0.3† | |
| Arterial oxygen partial pressure, mmHg (**,††) | D1 | 103 ± 4 | 90 ± 4 | 89 ± 2 | 88 ± 5 |
| D15 | 105 ± 5 | 94 ± 4 | 95 ± 5† | 96 ± 4† | |
| Arterial carbon dioxide partial pressure, mmHg (**,††) | D1 | 32 ± 2 | 37 ± 1 | 37 ± 1 | 32 ± 3 |
| D15 | 29 ± 2 | 35 ± 1 | 34 ± 2† | 25 ± 2† | |
| Arterial oxygen content, mLO2·100 ml−1 | D1 | 19.8 ± 0.6 | 19.8 ± 0.6 | 20.3 ± 0.7 | 20.7 ± 0.7 |
| D15 | 19.7 ± 0.5 | 20.0 ± 0.6 | 20.4 ± 0.5 | 19.9 ± 0.8 | |
| Delivery of oxygen, ml·min−1 (**) | D1 | 1,738 ± 134 | 3,041 ± 185 | 3,954 ± 266 | 5,199 ± 477 |
| D15 | 1,824 ± 163 | 3,306 ± 249 | 4,070 ± 304 | 4,586 ± 520 | |
| Fractional oxygen extraction, % (**) | D1 | 28 ± 4 | 56 ± 3 | 67 ± 3 | 69 ± 4 |
| D15 | 25 ± 1 | 52 ± 3 | 65 ± 4 | 74 ± 7 | |
| Hb, g·dl−1 (**) | D1 | 14.5 ± 0.5 | 14.6 ± 0.5 | 15.1 ± 0.5 | 15.6 ± 0.5 |
| D15 | 14.3 ± 0.4 | 14.7 ± 0.4 | 15.0 ± 0.3 | 15.6 ± 0.3 | |
| COHb, % of total Hb (**,††) | D1 | 1.1 ± 0.0 | 1.1 ± 0.0 | 1.1 ± 0.0 | 1.0 ± 0.0 |
| D15 | 1.6 ± 0.1† | 1.3 ± 0.1† | 1.3 ± 0.1† | 1.3 ± 0.0† | |
| Bicarbonate, mmol·l−1 (**,††) | D1 | 23 ± 1 | 23 ± 1 | 22 ± 1 | 15 ± 2 |
| D15 | 21 ± 1 | 23 ± 1 | 20 ± 1† | 12 ± 1† | |
| pH (**) | D1 | 7.46 ± 0.02 | 7.42 ± 0.01 | 7.40 ± 0.01 | 7.30 ± 0.03 |
| D15 | 7.49 ± 0.02 | 7.42 ± 0.00 | 7.39 ± 0.01 | 7.28 ± 0.02 | |
| Lactate, mmol·l−1 (**) | D1 | 2.0 ± 0.3 | − | − | 14.5 ± 1.4 |
| D15 | 1.9 ± 0.5 | − | − | 12.9 ± 1.8 | |
Data are mean ± SEM. D1: Day 1. D15: Day 15.
*
,†Significant interaction.
†
Significantly different to Day 1.
**
Significant main effect of exercise.
††
Significant main effect of Day (Drug).