Table 3

Breathing pattern, ventilatory response to CO2, P01 and dyspnoea perception (Borg scale) at peak rebreathing

Test duration, min3.76±0.273.80±0.383.95±0.470.3
Respiratory rate, /min18.48±5.9521.57±5.3521.32±4.310.2
Tidal volume, L2.29±0.981.38±0.42*1.43±0.41*0.02
Δ Tidal volume (vs baseline), L1.11±0.760.14±0.36*0.34±0.39*<0.005
Minute ventilation (VE), L/min40.13±18.1128.63±7.9530.48±10.130.3
ΔVE (vs baseline), L/min23.34±18.228.85±6.58*13.98±10.16<0.05
PetCO2, mm Hg54.53±4.3161.11±5.30*62.49±6.71*<0.01
Borg score3.6±1.576.35±1.54*2.32±1.94*<0.001
Δ Borg (vs baseline)3.40±1.505.53±1.42*1.35±0.82*<0.001
  • Results are expressed as mean±SD.

  • *p<0.05 vs controls.

  • PetCO2, end-tidal carbon dioxide tension; P01, mouth occlusion pressure 0.1 s after onset of inspiration.