Background: Maximal cardiopulmonary exercise testing is recommended on an annual

PurposeThis study characterised oxygen uptake efficiency (OUE) in children with mild-to-moderate cystic fibrosis (CF). Specifically, it investigated (1) the utility of OUE parameters as potential submaximal surrogates of peak oxygen uptake (), and (2) the relationship between OUE and disease severity.MethodsCardiopulmonary exercise test (CPET) data were collated from 72 children [36 CF, 36 age- and sex-matched controls (CON)], with OUE assessed as its highest 90-s average (plateau; OUEP), the gas exchange threshold (OUEGET) and respiratory compensation point (OUERCP). Pearson’s correlation coefficients, independent t tests and factorial ANOVAs assessed differences between groups and the use of OUE measures as surrogates for .ResultsA significant (p < 0.05) reduction in allometrically scaled and all OUE parameters was found in CF. Significant (p < 0.05) correlations between measurements of OUE and allometrically scaled , were observed in CF (r = 0.49–0.52) and CON (r = 0.46–0.52). Furthermore, measures of OUE were significantly (p < 0.05) correlated with pulmonary function (FEV1%predicted) in CF (r = 0.38–0.46), but not CON (r = −0.20–0.14). OUEP was able to differentiate between different aerobic fitness tertiles in CON but not CF.ConclusionsOUE parameters were reduced in CF, but were not a suitable surrogate for . Clinical teams should, where possible, continue to utilise maximal CPET parameters to measure aerobic fitness in children and adolescents with CF. Future research should assess the prognostic utility of OUEP as it does appear sensitive to disease status and severity.

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