Effects of obesity on the oxygen cost of breathing in children.

The objective of this study was to examine the effects of obesity on the oxygen (O) cost of breathing using the eucapnic voluntary hyperpnea (EVH) technique in 10- and 11-year-old children. Seventeen children (8 without and 9 with obesity) underwent EVH trials at two levels of ventilation for assessing the O cost of breathing (slope of oxygen uptake, V˙O vs. minute ventilation) and a dual energy x-ray absorptiometry scan. Resting and EVH V˙O was higher in children with obesity when compared with children without obesity (P = 0.0096). The O cost of breathing did not statistically differ between children without (2.09 ± 0.46 mL/L) and with obesity (2.08 ± 0.64 mL/L, P = 0.99), but the intercept was significantly greater in children with obesity. Chest mass explained 85 % of the variance in resting V˙O in children with obesity. Higher resting energy requirements, attributable to increased chest mass, can increase the absolute metabolic costs of exercise and hyperpnea in children with obesity.