Trikafta Exercise Study in Cystic Fibrosis

Inclusion Criteria: * Confirmed diagnosis of CF and at least one copy of the F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene * Plan to initiate Trikafta by the treating physician within 30 days of the enrolment visit * Aged 19 years or older * Stable clinical status based on clinical judgment of the treating physician * Forced Expiratory Volume in 1 second (FEV1.0) \< 90% predicted * Body mass index greater than 16 or less than 30 kg/m\^2 * Currently non-smoking or a past smoking history of less than 20 pack-years * Able to read and understand English * Fully vaccinated (at least 2 doses) for Covid-19 Exclusion Criteria: * A disease other than CF that could importantly contribute to dyspnea or exercise limitation * Chronic airway infection with Mycobacterium abscessus, Burkholderia cepacia complex, or other organisms with infection control implications based on the treating physicians * Contraindications to clinical exercise testing * Use of supplemental oxygen or desaturation less than 85% with exercise * Diagnosis of pneumothorax in the past 4 weeks * History of organ transplantation