Importance of proper scaling of aerobic power when relating to cardiometabolic risk factors in children

Abstract

Background: The relationship between cardiometabolic risk factors (CMRF) and aerobic power (VO_2max) scaled as mL O₂ per kilogram body mass is controversial because mass includes both fat and fat-free mass, and fat mass is independently associated with the CMRF.

Aim: To examine common units used to scale VO_2max and their relationships to mean blood pressure (MBP), total cholesterol (TC), HDL cholesterol, triglycerides (TG), insulin resistance (HOMA-IR) and cumulative risk score (z-score).

Subjects: 1784, 8–18 year-old youths, 938 girls and 886 boys.

Methods: Fasting blood samples were obtained. VO_2max was estimated in mL/min from cycle ergometry and scaled to body mass (kg), fat free mass (kg_FFM), body surface area (m²), height (cm) and allometric (mL/kg^0.67/min).

Results: Unadjusted correlations between CMRF and many of the scaled VO_2max units were significant (p < 0.0001), especially for MBP, HOMA-IR, HDL and z-score, with lower correlations for TC and TG. After adjusting for ancestry, sex, height and body fat associations were greatly weakened (r < 0.09), except for MBP.

Conclusions: On a population basis, the physical characteristics of the child, especially body fat, are more related to CMRF than any scaled units of VO_2max; thus care is needed when relating fitness and health issues.

Keywords::

• Mean blood pressure
• cholesterol
• insulin resistance
• body fat
• fat-free mass
• VO_2max

Declaration of Interest: This study was supported by a grant from the National Institute of Nursing of the NIH, Grant #NR01837. The authors report no conflicts of interest, financial or otherwise, with the methods or information provided within the manuscript.