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