Adapting the "chester step test" to predict peak oxygen uptake in children

Abstract

AIM OF THE STUDY: Maximal exercise testing may be dif-ficult to perform in clinical practice, especially in obese children who have low cardiorespiratory fitness and ex-ercise tolerance. We aimed to elaborate a model pre-dicting peak oxygen consumption (VO2) in lean and obese children with use of the submaximal Chester step test. METHODS: We performed a maximal step test, which consisted of 2-minute stages with increasing intensity to exhaustion, in 169 lean and obese children (age range: 7-16 years). VO2 was measured with indirect calorime-try. A statistical Tobit model was used to predict VO2 from age, gender, body mass index (BMI) z-score and in-tensity levels. Estimated VO2peak was then determined from the heart rate-VO2 linear relationship extrapolated to maximal heart rate (220 minus age, in beats.min-1). RESULTS: VO2 (ml/kg/min) can be predicted using the following equation: VO2 = 22.82 - [0.68∗BMI z-score] - [0.46∗age (years)] - [0.93∗gender (male = 0; female = 1)] + [4.07∗intensity level (stage 1, 2, 3 etc.)] - [0.24∗BMI z-score ∗intensity level] - [0.34∗gender∗intensity level]. VO2 was lower in participants with high BMI z-scores and in female subjects. CONCLUSION: The Chester step test can assess cardi-orespiratory fitness in lean and obese children in clinical settings. Our adapted equation allows the Chester step test to be used to estimate peak aerobic capacity in chil-dren.