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The oxygen uptake efficiency slope is not a valid surrogate of aerobic fitness in cystic fibrosis

Research output: Contribution to journalArticlepeer-review

  • Craig A. Williams
  • Owen W. Tomlinson
  • Lucy V. Chubbock
  • Daniel Stevens
  • Dr Zoe Saynor
  • Patrick J. Oades
  • Alan Robert Barker
Background - Maximal cardiopulmonary exercise testing is recommended on an annual basis for children with cystic fibrosis (CF), due to a clinically useful prognostic information provided by maximal oxygen uptake (V̇O2max). However, not all patients are able, or willing, to reach V̇O2max, and therefore submaximal alternatives are required. This study explored the validity of the oxygen uptake efficiency slope (OUES) as a submaximal measure of V̇O2max in children and adolescents with CF.

Methods - Data were collated from 72 cardiopulmonary exercise tests (36 CF, 36 controls), with OUES determined relative to maximal and submaximal parameters of exercise intensity, time and individual metabolic thresholds. Pearson’s correlation coefficients, independent t-tests and factorial ANOVAs were used to determine validity.

Results - Significant (p < 0.05) correlations with V̇O2max were observed for most expressions of OUES, but were consistently weaker in CF (r = 0.30 – 0.47) when compared to CON (r = 0.58 – 0.89). Mean differences for all OUES parameters between groups were not significant (p > 0.05). When split by V̇O2max tertiles, minimal significant differences were found between, and within, groups for OUES, indicating poor discrimination of V̇O2max.

Conclusions - The OUES is not a valid (sub)maximal measure of V̇O2max in children and adolescents with mild-to-moderate CF. Clinicians should continue to use maximal markers (i.e. V̇O2max) of exercise capacity.
Original languageEnglish
Pages (from-to)36-42
Number of pages7
JournalPediatric Pulmonology
Issue number1
Early online date24 Oct 2017
Publication statusPublished - 1 Jan 2018


  • The oxygen update efficiency slope

    Rights statement: This is the peer reviewed version of the following article: Williams CA, Tomlinson OW, Chubbock LV, et al. The oxygen uptake efficiency slope is not a valid surrogate of aerobic fitness in cystic fibrosis. Pediatr Pulmonol. 2017; 1–7., which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

    Accepted author manuscript (Post-print), 498 KB, PDF document

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