5. Research Plan: Design: cross-sectional retrospective/prospective study population. The retrospective study will include data analysis of patients that preformed exercise tests as part of their clinical evaluation. In the prospective study, informed consent will be sign by the patient or legal guardian prior to participation. Setting: Outpatient clinic. The aim is to evaluate 50 patients with CF and 50 non-CF bronchiectasis patients from the exercise clinic at the Pediatric Pulmonary Institute at the Rappaport Children's Hospital.