The long-term consequences of vigorous physical activity (PA) on cystic fibrosis lung function remain unknown. This study used motivational feedback to assess the impact of a 12-month partially supervised PA intervention. A parallel-arm multicenter randomized controlled study (ACTIVATE-CF) randomly assigned generally inactive patients aged 12 years to an intervention or control group (1:1 ratio). The intervention group agreed to add 3 hours of strenuous PA each week, whereas the control group maintained their current PA habits. At 6 months, the primary endpoint was the percent change anticipated forced expiratory volume in 1s (ΔFEV1). The secondary objectives were PA, exercise capacity, exercise motivation, time to first exacerbation rates, quality of life, anxiety, depression, stress, and blood glucose management. Mixed linear models were used to analyze the data.

A total of 117 patients (40% of the planned sample size) were randomly assigned to one of two groups: intervention (n=60) or control (n=57). After 6 months, the control group’s ΔFEV1 was considerably higher than the intervention group’s (2.70% expected, 95% CI 0.13 to 5.26; p=0.04). At each research visit, the intervention group reported more vigorous PA than the control group, had higher exercise capacity at 6 and 12 months, and had higher PA at 12 months. Other secondary outcomes showed no influence. The effects of ACTIVATE-CF on vigorous PA and exercise capacity lasted for 6 months. However, the control group had better FEV1 than the ACTIVATE-CF group.