Ring AM, et al. - Researchers tested the hypothesis that children with Cystic Fibrosis (CF) would have consistently lower Peak oxygen uptake (VO_2peak) and pulmonary function than children with primary ciliary dyskinesia (PCD). This is the first report suggesting equal and consistent reduction in fitness in both children with PCD and CF along with a consistent lower pulmonary function in PCD compared with CF. A certain reservation for possible selection bias and the small number of patients seemed necessary. However, findings justify increased focus on early diagnosis, evidence-based treatment regimens and close clinical monitoring in PCD.