Table 2.
O2 transport and blood flow data during the 5 min exercise tests
| Variable | Hypoxia | Normoxia | Hyperoxia |
|---|---|---|---|
| WR (W) | 235 ± 6* | 290 ± 5 | 325 ± 6* |
| CO (l min−1) | 27.6 ± 1.2 | 28.4 ± 1.9 | 27.8 ± 1.6 |
| SV (l) | 0.166 ± 0.008 | 0.169 ± 0.019 | 0.166 ± 0.011 |
| HR (beats min−1) | 169 ± 8 | 175 ± 9 | 174 ± 9 |
 legs (ml l−1) |
135.6 ± 9.2* | 170.5 ± 5.2 | 185.3 ± 10.1* |
 f systemic (ml l−1) |
122.7 ± 14.5* | 151.2 ± 27.9 | 158.2 ± 25.5 |
| Syst O2 del (l min−1) | 4.15 ± 0.14* | 5.55 ± 0.32 | 6.07 ± 0.30* |
| Legs O2 ex (%) | 89.9 ± 1.0* | 86.9 ± 1.7 | 84.7 ± 2.2* |
Whole body  (l min−1) |
3.3 ± 0.1* | 4.2 ± 0.1 | 4.3 ± 0.1 |
| IMBF (ml (100 ml)−1 min−1) | 53.6 ± 8.5 | 49.9 ± 5.9 | 52.9 ± 5.9 |
| WOB (J min−1) | 353 ± 29 | 347 ± 34 | 401 ± 29 |
| IMBF/WOB (ml (100 ml)−1 J−1) | 0.151 ± 0.29 | 0.144 ± 0.17 | 0.132 ± 0.20 |
| QMBF (ml (100 ml)−1 min−1) | 100.4 ± 8.7 | 94.4 ± 5.2 | 95.1 ± 7.8 |
| QMBF/WR (ml (100 ml)−1 min−1 W−1) | 0.43 ± 0.9* | 0.33 ± 0.10 | 0.29 ± 0.8 |
WR, work rate; CO, cardiac output; SV, stroke volume; HR, heart rate; 
, arterio-venous difference; O2 del, O2 delivery; O2 ex (%), percentage O2 extraction; 
, oxygen uptake;. RMBF, respiratory muscle blood flow; WOB, work of breathing; IMBF/WOB, intercostal muscle blood flow as a function of the WOB calculated over the same period as IMBF; QMBF, quadriceps muscle blood flow assessed by NIRS; QMBF/WR quadriceps muscle blood flow as a function of the work rate. Asterisks denote significant differences (P < 0.05) compared with normoxia.