Habitual physical activity in children and adolescents with cystic fibrosis

This study was conducted to: 1) measure total physical activity levels, including the intensities of the various types of activities, in children and adolescents with CF compared with non-CF healthy control subjects; and 2) determine whether vigorous activity level was related to aerobic fitness and disease status in patients with CF.

Thirty patients with CF (18 male, 12 female) and 30 control subjects (17 male, 13 female), 7-17 yr old, participated in this study. Habitual physical activity was measured using Kriska's Modifiable Activity Questionnaire (MAQ) and the past year's average of total hours, MET-hours, and vigorous (VIG) hours (>6 METs) of activity per week were determined. Aerobic fitness was determined from peak oxygen uptake (VO2peak) obtained via maximal exercise testing on a cycle ergometer. Standard spirometry was used to measure pulmonary function. Body mass index (BMI) was determined from height and weight measurements.

The CF and control groups were similar in age and gender distribution, but the patients were smaller (BMI, 98 vs 112% of predicted) and less aerobically fit (36.5 vs 41.4 mL x kg(-1) x min(-1)). Total and MET-hours of physical activity did not differ between groups; however, the CF group participated in significantly fewer hours of vigorous activities than the control group (2 vs 3.7 h x wk(-1)). In patients with worse lung disease, VIG-h x wk(-1) were significantly related to VO2peak (r = 0.83).

These results suggest that children with CF engage in less vigorous physical activities than their healthy non-CF peers, despite having good lung function. In view of the progressive nature of the disease, and the association between aerobic fitness and vigorous activity, patients should be encouraged to engage in more vigorous activities that promote aerobic fitness and may ultimately have an impact on survival.