Table 1.
Response to final minute of constant-load exercise for control (CTRL), inspiratory muscle unloading (PAV), inspiratory resistive loading (IRL) and inspiratory resistive loading-control (IRL-CTRL)
| Variable | CTRL | PAV | IRL | IRL-CTRL |
|---|---|---|---|---|
| Power output (W) | 292 ± 13 | 292 ± 13 | ||
| Exercise time (min) | 13.2 ± 0.9 | 7.9 ± 0.6** | ||
| ∫Poe×fR((cmH2O s)× min) | 648 ± 48 | 285 ± 37** | 1131 ± 58 | 636 ± 44†† |
| ∫Pdi×fR((cmH2O s)× min) | 844 ± 53 | 534 ± 55** | 1252 ± 57 | 845 ± 48†† |
| SpO2 (%) | 93.1 ± 1.0 | 94.7 ± 0.7 | 93.0 ± 1.3 | 93.7 ± 0.7 |
| HR (beats min−1) | 180 ± 4 | 178 ± 3 | 175 ± 4 | 176 ± 3 |
| Ti/Ttot | 0.47 ± 0.01 | 0.43 ± 0.02 | 0.56 ± 0.01 | 0.48 ± 0.01†† |
| fR (breaths min−1) | 52.6 ± 3.6 | 43.3 ± 3.3* | 44.3 ± 2.6 | 44.1 ± 3.1 |
| VT (l) | 2.88 ± 0.15 | 3.77 ± 0.23** | 2.92 ± 0.17 | 3.25 ± 0.15†† |
| V˙E (l min−1) | 148.4 ± 5.9 | 159.4 ± 8.8 | 126.3 ± 4.2 | 140.8 ± 7.0† |
| V˙O2 (l min−1) | 4.00 ± 0.14 | 3.66 ± 0.13** | 3.90 ± 0.11 | 3.69 ± 0.13† |
| V˙O2 (% V˙O2peak) | 96 ± 2 | 88 ± 1** | 94 ± 2 | 88 ± 2† |
| V˙E/V˙O2 | 37.2 ± 1.3 | 43.8 ± 2.7* | 33.6 ± 1.0 | 36.2 ± 1.5 |
| V˙E/V˙CO2 | 37.5 ± 1.1 | 40.7 ± 1.9 | 30.4 ± 0.6 | 32.8 ± 1.2† |
| [La−]B (mm) | 10.0 ± 1.1 | 9.2 ± 0.6 | 9.0 ± 0.7 | 9.2 ± 0.7 |
| RPE (dyspnoea) | 10.0 ± 0.3 | 8.4 ± 0.6* | 9.8 ± 0.3 | 7.9 ± 0.5†† |
| RPE (limb) | 10.2 ± 0.1 | 9.0 ± 0.4* | 8.8 ± 0.4 | 7.9 ± 0.5† |
Mean ±s.e.m.n = 8 per group.
P < 0.05
P < 0.01, significantly different from CTRL.
P < 0.05
P < 0.01, significantly different from IRL.
The IRL and IRL-CTRL values are the mean of two trials performed on different days. ∫Poe×fR, pressure–time product for the inspiratory muscles; ∫Pdi×fR, pressure–time product for the diaphragm; SpO2, arterial O2 saturation via pulse oximetry; HR, heart rate; TiTtot, inspiratory duty cycle; fR, respiratory frequency; VT, tidal volume; V˙E, minute ventilation; V˙O2 uptake; V˙CO2, CO2 production; [La−]B, blood lactate concentration; RPE, ratings of perceived exertion.