Evaluating Sensations of Breathlessness in Patients With Cystic Fibrosis

Shortness of breath (dyspnea) during exercise is a major source of distress and is a commonly reported symptom in patients with cystic fibrosis (CF). Due to the investigators' poor understanding of how dyspnea develops, there are no treatments that consistently reduce dyspnea in this population. The investigators aim to acquire a more comprehensive understanding of the physiological mechanisms of exertional dyspnea in CF patients. This study will likely identify an important physiological mechanism of dyspnea in CF and may contribute to the development and use of effective treatments to reduce dyspnea in this population. The central hypothesis is that the impaired tidal volume (VT) response during exercise in CF, in the setting of increased ventilatory demand will give rise to different qualitative descriptions of exertional dyspnea compared with healthy age and sex-matched controls. Specifically, CF patients will select "increased work and effort" as their dominant descriptor of dyspnea up to the VT inflection/plateau. Beyond this point, CF patient's dominant descriptor will become "unsatisfied inspiration." In contrast, healthy control participants will report "increased work and effort" throughout all phases of exercise and will not report "unsatisfied inspiration", even after the VT inflection/plateau.