The main objective of this study is to compare the effectiveness of two different exercise interventions in a patient-centered, home-based exercise program for improving cardiorespiratory-fitness in people with cystic fibrosis (CF). We hypothesize cystic fibrosis patients participating in a high intensity interval training (HIIT) group will experience greater improvements in cardiorespiratory-fitness than those in a moderate continuous training (MCT) group. Further, we plan to investigate the efficacy of the comparators on patient-centered outcomes.

This study is a randomized control trial that compares MCT to HIIT using a patient-centered and home-based delivery model with CF Care Centers in the United States. Participants will be randomly allocated to either an MCT or HIIT arm. Both the MCT and HIIT interventions are accepted forms of prescribed exercise in clinical practice. The interventions will be delivered with a telehealth platform using internet (HIPAA-Compliant video), phone, and email/text support. All study sites will receive initial and on-going training and program facilitation to assure consistency of delivering the intervention. All participants across both arms visit their respective CF clinics on a regular basis for routine CF care. Thus, our research team will be able to coordinate all testing/assessment visits, including long-term (18-month timepoint), with participants throughout the study. The primary and secondary outcomes include important patient-centered outcomes as selected by our study's CF Patient and Stakeholder Advisory Board.

Inclusion Criteria:

• diagnosed with Cystic Fibrosis
• Prescribed and taking for 28 days ivacaftor-tezacaftor-elexacaftor (Trikafta)
• 18 years and older

Exclusion Criteria:

• 17 years of age or less
• not eligible for ivacaftor-tezacaftor-elexacaftor (Trikafta)
• inability to exercise
• pregnancy
• status post lung transplantation
• already participating in more than 150 minutes of aerobic exercise per week