Fig. (2) Progression of twitch mouth pressures (TwPmo) for the two consecutive exercise protocols and recovery phase during spontaneous breathing (left panel) and during non-invasive ventilation (right panel). Data are presented as mean. T-bars represent 95% confidence interval of the mean. I-V represent consecutive measurements. HEET = heavy-intensity exercise testing; NIV = non-invasive ventilation; SB = spontaneous breathing.