Quantifying Maximal Oxygen Uptake using Lean Body Mass in Children with Obesity

Abstract

IntroductionThe purpose of this study was to examine whether maximal oxygen uptake (V̇O2max) prediction equations based on lean body mass can overcome the confounding effect of fat mass on quantification of cardiorespiratory fitness in children with obesity.MethodsForty‐nine children (23 with obesity; BMI ≥ 95th percentile) completed a dual‐energy x‐ray absorptiometry scan for estimating body composition and incremental maximal and verification exercise tests till volitional exhaustion for estimating V̇O2max. Prediction equations based on lean body mass (LBM) and body mass from Cooper D.M. et al 2016 were used to predict V̇O2max [Boys: (0.059 × LBM) − 0.103; (0.052 × body mass) − 0.266. Girls: (0.055 × LBM)–0.187; (0.037 × body mass) + 0.022].ResultsIn children without obesity, predicted V̇O2max based on body mass was 100 ± 10mL/min higher than predicted V̇O2max based on LBM (P < 0.001). In children with obesity, predicted V̇O2max based on body mass was 906 ± 33mL/min higher than predicted V̇O2max based on LBM (P < 0.001). Predicted V̇O2max based on body mass was more strongly associated with fat mass (r = 0.81) compared with predicted V̇O2max based on LBM (r = 0.51); P<0.001. The V̇O2max vs. LBM slope was similar for children with (0.040 L·min−1·kg−1) and without obesity (0.043 L·min−1·kg−1). Percent predicted V̇O2max based on LBM was 13% lower in children with obesity compared with children without obesity (P < 0.001). Percent predicted V̇O2max based on body mass was 37% lower in children with obesity compared with children without obesity (P < 0.001).ConclusionsReferencing V̇O2max to body mass substantially underestimates cardiorespiratory fitness in children with obesity due to the confounding effect of metabolically inactive fat mass. It would be prudent to measure LBM and reference V̇O2max to LBM for a less biased estimation of cardiorespiratory fitness in children with obesity.Support or Funding InformationThis research was supported by NIH R01 HL136643, Texas Health Presbyterian Hospital Dallas, King Charitable Foundation Trust, and unrestricted funds from Dr. Pepper Snapple.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.