Exercise and Oscillatory Positive Expiratory Pressure Therapy in Cystic Fibrosis

The investigators aim to compare a single bout of moderately intense cycling exercise incorporating Flutter® breathing maneuvers with a single bout of moderately intense cycling exercise alone on sputum viscoelasticity (primary endpoint) and the diffusion capacity of the lungs in adult patients with cystic fibrosis. The investigators further aim to analyze the short-term variability of resting diffusion capacity of carbon monoxide (DLCO) and nitric oxide (DLNO) in patients with cystic fibrosis.