Table 3.
Absolute values are means ± SD (n = 9)
| Period | NN | HH 3000 m | HN | NH | HH 5500 m | |
|---|---|---|---|---|---|---|
| VE (L/min) | Baseline | 12.1 ± 1.4 | 12.5 ± 1.4 | 10.3 ± 1.4 | 12.1 ± 2.7 | 16.0 ± 2.7*§#† |
| Hyperventilation | 39.5 ± 7.7 | 35.0 ± 8.0 | 35.6 ± 9.2 | 35.4 ± 6.9 | 40.4 ± 10.5† | |
| Hypercapnia | 15.2 ± 4.4 | 13.6 ± 3.0 | 11.4 ± 2.0 | 17.8 ± 4.0# | 14.1 ± 2.9† | |
| BF (cycle/min) | Baseline | 15.9 ± 2.6 | 16.7 ± 2.8* | 17.9 ± 3.0 | 17.0 ± 3.6 | 17.9 ± 2.7* |
| Hyperventilation | 12.7 ± 3.9 | 12.0 ± 2.9 | 12.0 ± 2.5 | 15.0 ± 4.8 | 11.5 ± 1.5 | |
| Hypercapnia | 16.1 ± 2.4 | 16.4 ± 2.1 | 17.2 ± 2.8 | 17.3 ± 2.8 | 16.0 ± 3.4 | |
| VT (L) | Baseline | 0.82 ± 0.21 | 0.79 ± 0.20 | 0.62 ± 0.21 | 0.79 ± 0.27 | 0.98 ± 0.31 (*)§ |
| Hyperventilation | 3.35 ± 0.99 | 3.04 ± 0.90 | 3.12 ± 1.02 | 2.52 ± 1.00* | 3.62 ± 0.80§† | |
| Hypercapnia | 1.04 ± 0.23 | 0.84 ± 0.17* | 0.68 ± 0.16* | 1.06 ± 0.24# | 0.93 ± 0.26 (†) | |
| PETO2 (mmHg) | Baseline | 99.4 ± 8.0 | 59.7 ± 6.7* | 85.3 ± 9.4* | 45.0 ± 3.3*# | 36.1 ± 4.7*§# |
| Hyperventilation | 125.8 ± 4.7 | 81.4 ± 5.4* | 102.6 ± 12.7* | 58.9 ± 9.1 | 50.0 ± 7.1*§# | |
| Hypercapnia | 117.2 ± 7.1 | 70.0 ± 5.8* | 86.8 ± 12.9* | 58.6 ± 6.2*# | 41.4 ± 4.5*§#† | |
| PETCO2 (mmHg) | Baseline | 34.5 ± 2.8 | 28.5 ± 2.5* | 22.3 ± 2.4* | 30.8 ± 2.2*# | 19.9 ± 1.3*§† |
| Hyperventilation | 24.0 ± 3.9 | 20.8 ± 3.0 | 17.0 ± 3.2* | 24.2 ± 4.3# | 15.5 ± 2.6*§† | |
| Hypercapnia | 42.0 ± 2.8 | 31.4 ± 3.3* | 25.1 ± 1.7* | 40.5 ± 2.1# | 22.1 ± 1.7*§#† |
Ventilatory parameters: Minute ventilation (VE), breathing frequency (BF), tidal volume (VT), end‐tidal pressure in oxygen (PETO2) and carbon dioxide (PETCO2). For time period: baseline, hyperventilation, and hypercapnia (5% CO2). In normobaric normoxia (NN, Dübendorf altitude level of 440 m), hypobaric hypoxia (HH, at altitude level of 3,000 m and 5,500 m), hypobaric normoxia (HN, altitude level of 5,500 m in normoxia), and normobaric hypoxia (NH, altitude simulation of 5,500 m in normobaria). Statistical analysis was performed separately for altitude comparison in HH (NN, 3,000 m and 5,500 m HH) and for conditions comparison (NN, HN, NH, and 5,500 m HH). (*) p = .061, *p < .05 different from NN conditions; §p < .05 different from 3,000 m HH; #p < .05 different from HN; and (†) p = .058, †p < .05 different from NH.