Table 5.
Maximal exercise performance
| Values at peak exercise | 490 m | 1,650 m |
|---|---|---|
| Time, min:sec | 9:13 (7:45; 10:50) | 8:41* (6:46; 10:38) |
| Work rate, watts | 92 (73; 120) | 82* (63; 120) |
| % predicted | 75 (59; 94) | 69* (59; 87) |
| Heart rate, 1/min | 127 (115; 138) | 123 (115; 140) |
| % predicted | 80 (75; 88) | 80 (75; 88) |
| V′O2, L/min | 1.21 (0.90; 1.43) | 1.06 (0.88; 1.47) |
| % predicted | 67 (54; 85) | 63 (52; 86) |
| V′O2, mL/min/kg | 15.9 (14.2; 19.8) | 15.0* (12.5; 19.7) |
| % predicted | 78 (61; 85) | 65* (55; 90) |
| V′CO2, L/min | 1.23 (0.90; 1.57) | 1.10 (0.87; 1.54) |
| % predicted | 43 (37; 52) | 41 (29; 55) |
| Respiratory exchange ratio | 1.03 (0.93; 1.09) | 1.03 (0.95; 1.12) |
| Breath rate, L/min | 36 (29; 40) | 36* (32; 40) |
| V′E, L/min | 52 (40; 64) | 53* (38; 66) |
| BR, % | 20 (5; 30) | 12* (−3; 21) |
| V′E/VO2 | 38.4 (33.6; 45.2) | 42.0* (37.0; 48.3) |
| V′E/VCO2 | 37.6 (33.2; 43.8) | 41.0* (36.8; 47.4) |
| Pulse oximetry, % | 95 (88; 98) | 90* (85; 95) |
| Arterial pH | 7.37# (7.34; 7.39) | 7.40* (7.35; 7.42) |
| PaCO2, kPa | 5.4# (5.3; 5.8) | 4.7* (4.4; 4.9) |
| PaO2, kPa | 7.7# (7.1; 9.7) | 7.5* (6.5; 8.2) |
| SaO2, % | 92# (88; 95) | 89* (83; 90) |
| DAaPO2,25 kPa | 5.5# (3.6; 6.1) | 3.7* (3.1; 4.6) |
| Borg CR-10 dyspnea | 5 (4; 7) | 5 (4; 7) |
| Borg CR-10 leg | 3 (2; 5) | 3 (1; 5) |
Notes: Median (quartiles), n=31. Breathing reserve calculated by (MVV-V′E)/MVV*100;
*
P<0.05 vs 490 m;
#
Arterial blood gas analysis during maximal exercise was available in 31 patients at 1,650 m and in 12 patients at 490 m; changes in arterial blood gas between 490 and 1,650 m are presented for the 12 patients.
Abbreviations: BR, breathing reserve; DAaPO2, Alveolar–arterial PO2 difference; MVV, maximal voluntary ventilation; V′O2, oxygen uptake; V′CO2, carbon dioxide output; V′E, minute ventilation.