Effect of acute exacerbations on skeletal muscle strength and physical activity in cystic fibrosis.

BACKGROUND: Skeletal muscle weakness is an important complication of chronic respiratory disease. The effect of acute exacerbations on strength in patients with cystic fibrosis is not known. METHODS: Quadriceps (QMVC) and respiratory muscle strength were measured in patients at the time of acute admission, at discharge and one month later. Patients wore an activity monitor during admission and at one month. Convalescent values were compared to the stable clinic population. RESULTS: Data were available for 13 acute admissions and 25 stable CF outpatients. Strength and other parameters including daily step count did not differ significantly between the stable and one month post-admission groups. At admission, QMVC was 16.7 (8.3)% lower than at convalescence, whereas inspiratory muscle strength did not change significantly. Reduction in QMVC did not correlate with activity levels or with markers of systemic inflammation. CONCLUSION: Further research is needed to identify the mechanisms responsible for the reduction in QMVC.