ABSTRACT
BACKGROUND: Since available studies have provided conflicting results, this study investigated respiratory muscle function and its relationship with exercise capacity, degree of dyspnoea and leg discomfort, and quality of life in patients with Cystic Fibrosis (CF). METHODS: Using a cross-sectional design, 27 clinically stable adolescent and adult patients (f/m: 14/13, age: 26+/-7 years) were included. Data of respiratory muscle strength (P(i)max and P(e)max), lung function (spirometry), peripheral muscle strength (peak isometric quadriceps and hand-grip strength), symptom-limited exercise capacity (modified shuttle test, MST), post-exercise dyspnoea and leg discomfort (Borg scores), and quality of life (CFQ-14+, MRC) were obtained for further analysis. RESULTS: P(i)max of the total patient group was significantly higher than reference values (P(i)max=124+/-32% predicted), and correlated positively with the walk/run distance of the MST (r(s)=0.59, p=0.00). Female patients showed more dyspnoea and a more impaired lung function than male patients. However, P(i)max and P(e)max (% predicted) showed a tendency to be higher in female than in male patients. CONCLUSION: Increased work of breathing will have a conditioning effect on the respiratory muscles, suggesting that training-related inspiratory muscle strength can play a positive role in the limited exercise capacity of CF patients.