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The oxygen uptake efficiency slope is not a valid surrogate of aerobic fitness in cystic fibrosis
Author(s) -
Williams Craig A.,
Tomlinson Owen W.,
Chubbock Lucy V.,
Stevens Daniel,
Saynor Zoe L.,
Oades Patrick J.,
Barker Alan R.
Publication year - 2018
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.23896
Subject(s) - medicine , vo2 max , aerobic exercise , cystic fibrosis , physical therapy , cardiology , analysis of variance , repeated measures design , physical fitness , heart rate , blood pressure , statistics , mathematics
Background Maximal cardiopulmonary exercise testing is recommended on an annual basis for children with cystic fibrosis (CF), due to clinically useful prognostic information provided by maximal oxygen uptake (V̇O 2max ). However, not all patients are able, or willing, to reach V̇O 2max , and therefore submaximal alternatives are required. This study explored the validity of the oxygen uptake efficiency slope (OUES) as a submaximal measure of V̇O 2max 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 V̇O 2max 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 V̇O 2max tertiles, minimal significant differences were found between, and within, groups for OUES, indicating poor discrimination of V̇O 2max . Conclusions The OUES is not a valid (sub) maximal measure of V̇O 2max in children and adolescents with mild‐to‐moderate CF. Clinicians should continue to use maximal markers (ie, V̇O 2max ) of exercise capacity.