Longitudinal Evaluation of Physical Fitness in Adults with Cystic Fibrosis in the Era of CFTR-Modulating-Therapies

Purpose: Maintaining physical fitness plays an important role in the management of people with cystic fibrosis (pwCF). Longitudinal data on the course of physical fitness and the potential impact of the introduction of highly effective CFTR modulator therapy with elexacaftor/tezacaftor/ivacaftor (ETI) in adult pwCF are scarce. Methods: Health-related and skill-related components of physical fitness were assessed using an incremental cycle test (Wpeak), plus forward bend (FB), prone bent knee hip extension (HE), plank leg raise (PLR), standing long jump (SLJ), and standing on one leg (OLS). Relevant disease-specific clinical data (body mass index [BMI] and forced expiratory volume in 1 second [FEV1]) were recorded. Results: Twenty-eight adult pwCF (age 26.0 +/- 7.8 years) were followed over 5.6 +/- 0.9 years; 21 started ETI therapy during this period. Significant improvements from baseline were noted in BMI (p < 0.001) and health-related fitness components (HE, p = 0.002; PLR, p = < 0.001), whereas Wpeak and FB remained stable over time (all p > 0.05). Skill-related components (SLJ, OLS) showed no change (all p > 0.05). Subgroup analysis revealed significant improvements in BMI, FEV1, and health-related fitness measures of muscular strength and endurance (HE, p = 0.009; PLR, p < 0.001) only in pwCF using ETI. Conclusion: Despite the improvements, the impact of ETI on the individual parameters was small. Other factors than implementation of ETI alone need to be considered on the way to a high level of physical fitness in adult pwCF.