Effect of Scaling Peak Oxygen Uptake for Body Size and Composition to Assess Cardiometabolic Risk in Children

Abstract

Purpose: This study measured associations of peak oxygen uptake (V̇O 2peak ) with cardiometabolic risk factors and quantified cardiometabolic risk misclassification when scaling V̇O 2peak for body size and composition, comparing population-specific and universal V̇O 2peak cut points.

Methods: In a population sample of 332 Finnish children (164 girls, 9-11 yr), V̇O 2peak was determined using a maximal cycle ergometer test and scaled for body mass (BM) and lean mass (LM) using ratio and allometric methods. A continuous cardiometabolic risk score was calculated from age- and sex-specific z -scores of traditional risk factors, with "increased risk" defined as ≥1 SD above the mean. Receiver operating characteristic curves assessed the ability of V̇O 2peak to classify children at increased risk. Associations between V̇O 2peak and cardiometabolic risk factors were measured using linear regression analyses. The type and the extent of misclassification were calculated by comparing rank differences between allometric and ratio-scaled V̇O 2peak , using directly measured cardiometabolic risk versus V̇O 2peak cut points. Population-specific cut points based on previously reported cut points in this sample were compared with universal cut points from existing meta-analyses.

Results: Scaling using LM, or allometric methods, attenuated associations between V̇O 2peak and cardiometabolic risk factors. V̇O 2peak scaled by LM -1 , BM -0.49 , or LM -1.04 demonstrated poor ability to classify increased cardiometabolic risk, whereas V̇O 2peak scaled by BM -1 had the highest classification ability in girls and boys (AUC = 0.875 and 0.690, respectively, P < 0.01). Universal cut points produced fewer false-positive classifications than population-specific cut points.

Conclusions: V̇O 2peak appropriately scaled for body size and composition may have limited ability to distinguish cardiometabolic risk in children, with diminished associations with cardiometabolic risk factors. Screening for cardiometabolic risk in children using V̇O 2peak ratio scaled by BM may reflect body size rather than fitness.

Trial registration: ClinicalTrials.gov NCT01803776.

Keywords: ADIPOSITY; ALLOMETRY; CARDIORESPIRATORY FITNESS; CARDIOVASCULAR DISEASE; YOUTH.