Aim of the randomized controlled trial is to investigate the effects of endurance training with different intensities on physical performance, body composition and appetite regulation in people with cystic fibrosis.

Inclusion Criteria:

• confirmed diagnosis of cystic fibrosis by at least 2 sweat tests and / or by the presence of two CF mutations,
• willingness to participate in and to comply with the research project procedure,
• written informed consent of patients,
• age ≥ 18 years,
• FEV1 of pred. ≥ 40%,
• Stable condition (as indicated by absence of one or more signs: new or increased haemoptysis, increased malaise, fatigue or lethargy, temperature over 38°C, weight loss, sinus pain and a decrease in pulmonary function by 10% or more)

Exclusion Criteria:

• Severe pulmonary exacerbation,
• cor pulmonale,
• musculoskeletal discomfort that makes a regular exercise training impossible,
• untreated CF-related diabetes