Scaling of VO2max and Its Relationship With Insulin Resistance in Children.

The relationship between insulin resistance (HOMA-IR), percent body fat, and aerobic fitness (VO_2max per unit fat free mass; mL/kgFFM/min) was examined in 1,710 children. Percent body fat was estimated from sum of skinfolds, and VO_2max was estimated from submaximal cycle ergometer tests. Overnight fasting blood samples were obtained. VO_2max (mL/kgFFM/min) and percent body fat were correlated with HOMA-IR (r = -0.076, p < .002; r = .420, p < .001, respectively); as was VO_2max in units of mL/kg/min (r = -0.264, p < .001). When VO_2max in mL/kg/min was used, a progressive increase in HOMA-IR was found with decreasing fitness (p < .05). However, when mL/kgFFM/min was used, HOMA-IR scores remained similar between moderate-fit and low-fit group. The stronger association between aerobic fitness (mL/kg/min) and HOMA-IR is partially due to the significant association of fat mass to HOMA-IR. Therefore, our recommendation is to express aerobic fitness in units of mL/kgFFM/min to eliminate the confounding factor of adiposity and better understand the influence of muscle on insulin resistance. [ABSTRACT FROM AUTHOR]