Validity of the Oxygen Uptake efficiency Slope in Children with Cystic Fibrosis

Maximal oxygen uptake (VO_2max) is generally considered the most reliable single measure of an individual’s maximal cardiopulmonary exercise capacity. Although many healthy children as well as paediatric patients do not show a plateau in oxygen uptake (VO₂) during exercise, several authors (Rowland 1993; Armstrong et al., 1996) showed that this levelling-off of VO₂ is not essential for defining the highest VO₂ in children. Therefore, VO_2max is often replaced by peak VO₂ (peak VO₂), the highest VO₂ measured during incremental exercise testing (IET).