Association between Borg breathlessness scores and measured variables during exercise to exhaustion in 15 healthy subjects
| Parameter | Spearman (r) | 95% CI | p Value |
| EMGdi%max | 0.975 | 0.898 to 0.994 | <0.001 |
| PTPoes (cm H2O.s.l/min) | 0.975 | 0.898 to 0.994 | <0.001 |
| MV (l/min) | 0.975 | 0.898 to 0.994 | <0.001 |
| V′o2/kg (ml.min.kg) | 0.965 | 0.863 to 0.992 | <0.001 |
| PTPdi (cm H2O.s.l/min) | 0.965 | 0.863 to 0.992 | <0.001 |
| sEMGpara%max | 0.961 | 0.846 to 0.990 | <0.001 |
| RER | 0.951 | 0.812 to 0.988 | <0.001 |
| TTI | 0.951 | 0.812 to 0.988 | <0.001 |
| IC (l) | 0.672 | 0.099 to 0.909 | 0.023 |
| V′o2 (l/min) | 0.658 | 0.075 to 0.905 | 0.030 |
| V′co2 (l/min) | 0.135 | −0.520 to 0.690 | 0.692 |
| Petco2 (mm Hg) | 0.005 | −0.610 to 0.616 | 0.989 |
EMG, electromyogram; EMGdi%max, diaphragm EMG activity normalised to maximal evoked EMG during inspiratory manoeuvres; IC, inspiratory capacity; MV, minute ventilation; Petco2, end tidal carbon dioxide; PTPdi, diaphragm pressure time product; PTPoes, oesophageal pressure time product; RER, respiratory exchange ratio; sEMGpara%max, surface parasternal EMG activity normalised to maximal evoked EMG during inspiratory manoeuvres; TTI, tension time index; V′co2, carbon dioxide production; V′o2, oxygen uptake.