The combination of the corrector lumacaftor with the potentiator ivacaftor has been approved for treatment of cystic fibrosis (CF) patients homozygous for the Phe508del CFTR mutation. There are no reports detailing the effect of lumacaftor-ivacaftor on physical activity (PA) and exercise tolerance. We performed incremental cardiopulmonary exercise testing (CPET) and we assessed PA pre- and post 2 years initiation of lumacaftor-ivacaftor in three CF adults. PA of mild intensity improved by +13% in patient 1, + 84% in patients 2 and + 89% in patient 3. Oxygen uptake increased both at anaerobic threshold and at peak exercise (patient 1 + 33%, patient 2 + 42% and patient 3 + 20%). Daily physical activities and exercise tolerance improved after two years of lumacaftor-ivacaftor therapy.