Improvement in body composition following a supervised exercise-training program of adult patients with cystic fibrosis

Objectives: Maintenance of optimal nutritional status is a crucial issue for cystic fibrosis (CF) patients. Here, we evaluate the effects of an 8-week exercise training (ET) program on body composition in CF patients.

Methods: This prospective pilot observational study was conducted in adult CF subjects in stable condition following their annual check-up. The ET program consisted of three sessions per week and included aerobic training (≥30min), muscle strengthening, circuit training, and relaxation. Exercise tolerance (6-minute walk test, 6MWT), pulmonary function, quadriceps isometric strength, and body composition (bioelectrical impedance analysis of fat-free mass [FFM], fat mass, and body cell mass) were analyzed before and immediately after the ET program. A control group of CF patients who preferred not to participate in the ET program received the same evaluations.

Results: A total of 43 CF patients were enrolled and offered the ET program; 28 accepted (aged 28±5 years, forced expiratory volume in 1s [FEV₁] 48.8±19% predicted) and 15 declined the ET program but agreed to be part of the control group (matched for age and CF severity: 30.8±9 years, FEV₁ 51.8±16.5%). Pulmonary function was unchanged at the end of the ET program, but significant improvements were observed in 6MWT distance (from 520±96m to 562±105m, P<0.001) and muscle strength (331±141N to 379±168N, P<0.001). Although mean body mass index did not change, the ET group showed significantly increased FFM (43.85±8kg to 44.5±9.2kg, P=0.03) and a trend towards increased body cell mass (21.4±6 to 22.1±6.6kg, P=0.06). All other parameters were unchanged by ET. There were no significant correlations between the increase in FFM and the improvements in either 6MWT distance or muscle strength. The CF control group exhibited no significant changes in any parameters between evaluations.

Conclusions: ET significantly improved FFM, but not body mass index, in CF patients. The results illustrate the superiority of bioimpedancemetry for assessing changes in body composition and reveal the importance of ET for improving not only exercise tolerance but also nutritional status in these patients.