The Oxygen Uptake Efficiency Slope Does Not Accurately Predict VO2peak In Young Children

PURPOSE: Measuring VO2peak in children can be challenging. Factors such as young age, obesity, underlying comorbidities, or insufficient personal motivation may limit the ability of children to give maximal effort during cardiopulmonary exercise testing. The oxygen uptake efficiency slope (OUES) has been proposed as a predictor of VO2peak but results from the literature are conflicting. The purpose of this study is to evaluate the level of agreement between gold-standard measurements of VO2peak (GS-VO2peak) and estimates of VO2peak derived from the OUES in 5-year-old children. METHOD: Children (n = 65) were participants of the Glowing Study. GS-VO2peak was measured in the fasting state through an incremental cycle ergometer test. The test was terminated when children displayed signs consistent with maximal effort. To calculate the OUES, the slope was measured using data from the beginning of the workload until a target heart rate corresponding to 60% of the participants heart rate reserve. The predicted VO2peak (Pred-VO2peak) was obtained using linear regression analysis which modeled the association of GS-VO2peak and OUES. The level of agreement between GS-VO2peak and Pred-VO2peak was assessed using Bland Altman analysis. Mean bias was assessed using a 1-sample t-test on the mean value of the difference between measurements. Proportional bias (PB) was assessed by correlating the difference between methods on the average of the two methods. RESULTS: The regression equation to predict VO2peak (ml/min) was: 411.1 + 0.2912 x OUES. The average VO2peak was comparable between methods (GS-VO2peak = 652.6 ± 117.6 ml/min vs. Pred-VO2peak = 652.6 ± 48.6 ml/min, p = NS ). The mean bias was 0.0 ± 107 ml/min (p = NS), and the proportional bias was r = 0.74 (p < 0.0001). CONCLUSIONS: The OUES accurately predicted the mean VO2peak of the group. However, the predicted values did not consistently agree with the GS-VO2peak across the entire range of measurements. The observed strong proportional bias indicates that OUES alone is not a reliable predictor of VO2 peak in young children. *Ryan Uwaydat contributed as much as the first author. USDA-ARS Project 6026-51000-012-06S. EB and ECD are partially supported by the Center for Childhood Obesity Prevention (NIH-NIGMS 5P20GM109096).