Poor cardiorespiratory fitness is associated with increased all cause morbidity and mortality. In children with obesity, maximum oxygen uptake (V̇O2max) may not be achieved due to reduced motivation and peripheral fatigue. We aimed to identify a valid submaximal surrogate for V̇O2max in children with obesity.
Ninety-two children with obesity (7–16 years) completed a maximal exercise treadmill test and entered a three-month exercise and/or nutrition intervention after which the exercise test was repeated (n = 63). Participants were required to reach V̇O2max to be included in this analysis (n = 32 at baseline and n = 13 at both time-points). The oxygen uptake efficiency slope (OUES) was determined as the slope of the line when V̇O2 (L/min) was plotted against log V̇E. Associations between the maximal OUES, submaximal OUES (at 3, 4, 5 and 6 min of the exercise test) and V̇O2max were calculated.
In the cross-sectional analysis, V̇O2max (L/min) was strongly correlated with 5-min OUES independent of Tanner puberty stage and sex (R2 = .80, p < .001). Longitudinal changes in V̇O2max were closely reflected by changes in 5-min OUES independent of change in percent body fat (R2 = .63, p < .05).
The 5-min OUES is a viable alternative to V̇O2max when assessing children with obesity.
Dias, Masterson, Wallen, and Coombes are with the School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, Brisbane, Queensland, Australia. Tjonna, Hosseni, and Ingul are with the Dept. of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway. Davies is with the Children’s Nutrition Research Centre, The University of Queensland, Brisbane, Queensland, Australia. Cain is with the Heart Care Partners, The Wesley Hospital, Auchenflower, Brisbane, Queensland, Australia. Leong is with the Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, Queensland, Australia. Arena is with the Dept. of Physical Therapy, College of Applied Health Sciences, University of Illinois Chicago, Chicago, IL.