Assessment of the five-minute oxygen uptake efficiency slope in children with obesity

Purpose: Poor cardiorespiratory fitness is associated with increased all cause morbidity and mortality. In children with obesity, maximum oxygen uptake (VO) may not be achieved due to reduced motivation and peripheral fatigue. We aimed to identify a valid submaximal surrogate for VO in children with obesity. Method: 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 VO 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 VO (L/min) was plotted against logV? E. Associations between the maximal OUES, submaximal OUES (at 3, 4, 5 and 6 min of the exercise test) and VO were calculated. Results: In the cross-sectional analysis, V?O2max (L/min) was strongly correlated with 5-min OUES independent of Tanner puberty stage and sex (R = .80, p < .001). Longitudinal changes in VO were closely reflected by changes in 5-min OUES independent of change in percent body fat (R = .63, p < .05). Conclusion: The 5-min OUES is a viable alternative to VO when assessing children with obesity