Table 1.
Effects of clamping PetCO2 at 50 Torr throughout incremental exercise in normoxia
| Control Trial |
Clamp at 50 Torr from 0 W to Wmax |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Variable | 0 W | 100 W | 200 W | Wmax | Preclamp 0 W | 0 W | 100 W | 200 W | Wmax |
| Power, W | 0 ± 0 | 100 ± 0 | 200 ± 0 | 366 ± 45 | 0 ± 0 | 0 ± 0 | 100 ± 0 | 200 ± 0 | 344 ± 42.6‡ |
| HR, beats/min | 82 ± 13 | 108 ± 5 | 139 ± 10 | 183 ± 8 | 78 ± 15 | 81 ± 13 | 111 ± 13 | 141 ± 17 | 175 ± 8‡ |
| V̇e, l/min | 19.5 ± 7.1 | 42.7 ± 4.2 | 74.1 ± 5.4 | 169.4 ± 17.7 | 18.7 ± 3.4 | 51.3 ± 17.9* | 86.4 ± 20.5‡ | 113.7 ± 17.7‡ | 159.7 ± 25.7 |
| RR, breaths/min | 16 ± 6 | 22 ± 7 | 29 ± 5 | 58 ± 6 | 16 ± 7 | 20 ± 5 | 29 ± 6† | 35 ± 6‡ | 56 ± 10 |
| Vt, l/breath | 1.3 ± 0.3 | 2.1 ± 0.5 | 2.7 ± 0.5 | 2.9 ± 0.2 | 1.3 ± 0.3 | 2.5 ± 0.6* | 3.0 ± 0.5‡ | 3.2 ± 0.3‡ | 2.9 ± 0.4 |
| PetCO2, Torr | 34 ± 4 | 42 ± 15 | 46 ± 16 | 33 ± 3 | 33 ± 4 | 50 ± 1* | 51 ± 1‡ | 50 ± 2† | 52 ± 5‡ |
| PetO2 Torr | 84 ± 7 | 75 ± 7 | 78 ± 5 | 91 ± 4 | 84 ± 4 | 110 ± 5* | 98 ± 7‡ | 92 ± 6‡ | 92 ± 5† |
| V̇e/V̇co2 | 34 ± 9 | 23 ± 5 | 26 ± 6 | 40 ± 9 | 33 ± 6 | 116 ± 35* | 51 ± 11‡ | 41 ± 6‡ | 43 ± 7 |
| V̇e/V̇co2 | 36 ± 9 | 28 ± 7 | 26 ± 6 | 32 ± 8 | 37 ± 3 | 177 ± 59* | 62 ± 18‡ | 39 ± 9‡ | 37 ± 6 |
| V̇co2, l/min | 0.6 ± 0.2 | 1.9 ± 0.4 | 3.0 ± 0.4 | 4.3 ± 0.6 | 0.6 ± 0.2 | 0.5 ± 0.1 | 1.7 ± 0.3 | 2.8 ± 0.2 | 3.8 ± 0.7† |
| V̇co2, l/min | 0.6 ± 0.4 | 1.6 ± 0.6 | 3.1 ± 1.1 | 5.5 ± 1.5 | 0.5 ± 0.1 | 0.3 ± 0.1* | 1.4 ± 0.1 | 3.0 ± 0.3 | 4.4 ± 0.7 |
| CBFv, cm/s | 47 ± 9 | 55 ± 10 | 59 ± 13 | 56 ± 11 | 43 ± 5 | 71 ± 14* | 77 ± 17‡ | 76 ± 12‡ | 78 ± 13‡ |
| SpO2, % | 97 ± 2 | 96 ± 3 | 95 ± 3 | 91 ± 5 | 97 ± 2 | 99 ± 2* | 99 ± 2 | 98 ± 3 | 91 ± 5 |
| Cerebral oxygenation | |||||||||
| ΔTSI, % | 0 ± 0 | −3.6 ± 4.1 | −4.8 ± 4.7 | −18.9 ± 11.4 | 0 ± 0 | 9.5 ± 4.6* | 9.1 ± 5.5‡ | 5.9 ± 7.0‡ | −5.9 ± 10.8‡ |
| ΔO2Hb, μM | 0 ± 0 | −4.5 ± 2.0 | −2.6 ± 4.7 | −1.7 ± 6.3 | 0 ± 0 | 5.1 ± 2.4* | 3.3 ± 2.9‡ | 1.8 ± 3.3‡ | 2.6 ± 6.4‡ |
| ΔHHb, μM | 0 ± 0 | 1.1 ± 1.2 | 1.9 ± 2.7 | 7.7 ± 5.4 | 0 ± 0 | −1.7 ± 1.5* | −1.6 ± 1.6‡ | −0.6 ± 2.7‡ | 6.7 ± 5.7 |
| ΔTHb, μM | 0 ± 0 | −3.4 ± 1.8 | −0.7 ± 3.0 | 6.0 ± 6.8 | 0 ± 0 | 3.4 ± 2.7* | 1.8 ± 2.8‡ | 1.2 ± 3.6 | 9.0 ± 8.0 |
| Muscle oxygenation | |||||||||
| ΔO2Hb, μM | 0 ± 0 | −8.8 ± 3.2 | −12.8 ± 4.5 | −16.3 ± 5.8 | 0 ± 0 | −1.0 ± 1.5 | −6.5 ± 3.4 | −10.4 ± 4.9 | −14.1 ± 3.0 |
| ΔHHb, μM | 0 ± 0 | 6.9 ± 4.7 | 13.8 ± 6.1 | 18.5 ± 6.3 | 0 ± 0 | 0.5 ± 2.3 | 6.1 ± 4.2 | 12.5 ± 6.0 | 18.3 ± 5.1 |
| ΔTHb, μM | 0 ± 0 | −1.8 ± 4.8 | 1.0 ± 5.6 | 2.2 ± 6.1 | 0 ± 0 | −0.5 ± 2.6 | −0.5 ± 3.4 | 2.7 ± 3.4 | 4.2 ± 4.3 |
Values are means ± SD; n = 9 subjects. Wmax, maximal power output; HR, heart rate; V̇e, expired volume; RR, respiratory rate; Vt, tidal volume; PetCO2, end-tidal Pco2; PetO2, end-tidal Po2; V̇e/V̇o2, ventilatory equivalent for oxygen; V̇e/V̇co2, ventilatory equivalent for carbon dioxide; V̇o2, volume of oxygen consumed; V̇co2, volume of carbon dioxide produced; CBFv, mean cerebral blood flow velocity of the middle cerebral artery; SpO2, arterial pulse saturation; ΔTSI, change in tissue saturation index; ΔO2Hb, change in oxygenated hemoglobin; ΔHHb, change in deoxygenated hemoglobin; ΔTHb, change in total hemoglobin.
Different from preclamp (P < 0.01).
Different from control trial (P < 0.05).
Different from control trial (P < 0.01).