Table 1.
Energy expenditure (EE), pulmonary ventilation (VE), and heart rate (HR) at rest and each gait speed under three oxygen concentrations. Changes in these variables (Δ) under moderate and severe hypoxia versus normoxia are shown.
| Normoxia | Moderate | Severe | |||
|---|---|---|---|---|---|
| EE, Watts | ΔEE | ΔEE | |||
| Rest | 103 ± 18 | 100 ± 9 | −3 | 106 ± 12 | 3 |
| 0.67 m s−1 | 211 ± 23 | 205 ± 23 | −6 | 218 ± 20 | 7 |
| 0.86 m s−1 | 230 ± 28 | 224 ± 23 | −6 | 236 ± 23 | 6 |
| 1.06 m s−1 | 252 ± 34 | 253 ± 28 | 1 | 261 ± 33 | 9 |
| 1.25 m s−1 | 281 ± 34 | 285 ± 31 | 4 | 288 ± 39 | 7 |
| 1.44 m s−1 | 328 ± 50 | 332 ± 36 | 4 | 338 ± 49 | 10 |
| 1.64 m s−1 | 412 ± 64 | 415 ± 59 | 3 | 424 ± 59 | 12 |
| 1.83 m s−1 | 495 ± 83 | 499 ± 79 | 4 | 513 ± 78 | 18* |
| V E ,L min −1 | ΔV E | ΔV E | |||
| Rest | 10.9 ± 0.8 | 11.2 ± 1.4 | 0.3 | 12.6 ± 1.4 | 1.7 |
| 0.67 m s−1 | 18.5 ± 2.5 | 18.1 ± 2.3 | −0.4 | 21.4 ± 3.2 | 2.9 |
| 0.86 m s−1 | 20.2 ± 2.8 | 19.7 ± 2.7 | −0.5 | 23.9 ± 4.0 | 3.7*† |
| 1.06 m s−1 | 21.8 ± 3.4 | 22.0 ± 3.4 | 0.2 | 26.7 ± 4.9 | 4.9*† |
| 1.25 m s−1 | 24.9 ± 3.1 | 25.5 ± 4.3 | 0.6 | 30.9 ± 6.8 | 6.0*† |
| 1.44 m s−1 | 28.0 ± 3.2 | 28.9 ± 3.9 | 0.9 | 36.7 ± 7.0 | 8.7*† |
| 1.64 m s−1 | 33.3 ± 4.3 | 34.9 ± 5.9 | 1.6 | 45.6 ± 9.4 | 12.3*† |
| 1.83 m s−1 | 40.5 ± 5.3 | 42.2 ± 8.5 | 1.7 | 58.8 ± 15.7 | 18.3*† |
| HR, bpm | ΔHR | ΔHR | |||
| Rest | 80 ± 11 | 83 ± 10 | 3 | 93 ± 11 | 13*† |
| 0.67 m s−1 | 78 ± 10 | 83 ± 8 | 5 | 98 ± 11 | 20*† |
| 0.86 m s−1 | 82 ± 10 | 85 ± 9 | 3 | 103 ± 11 | 21*† |
| 1.06 m s−1 | 84 ± 11 | 89 ± 9 | 5 | 107 ± 11 | 23*† |
| 1.25 m s−1 | 89 ± 11 | 94 ± 9 | 5 | 114 ± 10 | 25*† |
| 1.44 m s−1 | 94 ± 10 | 101 ± 9 | 7‡ | 123 ± 12 | 29*† |
| 1.64 m s−1 | 101 ± 11 | 109 ± 8 | 8‡ | 136 ± 12 | 35*† |
| 1.83 m s−1 | 109 ± 12 | 119 ± 9 | 10‡ | 146 ± 14 | 37*† |
Values are mean ± standard deviation. bpm; beats per minute. *P < 0.05 between normoxia and severe hypoxia, † P < 0.05 between moderate and severe hypoxia, ‡ P < 0.05 between normoxia and moderate hypoxia.