New incremental field step-test (iSTEP) is valid and feasible in measuring near maximal exercise performance in children with cystic fibrosis

Background: Progression of lung disease in cystic fibrosis (CF) inevitably reduces exercise capacity. To monitor the effects of disease progression, therapeutic interventions or exercise training, health care professionals require sensitive and appropriate methods of assessing and monitoring exercise performance. Exercise testing is an important standard of care for all children and adults with CF but available field exercise tests have...