Weight loss associated with exercise training restores ventilatory efficiency in obese children.

The purpose of this study was to test the hypothesis that in obese children: 1) Ventilatory efficiency (VentE) is decreased during graded exercise; and 2) Weight loss through diet alone (D) improves VentE, and 3) diet associated with exercise training (DET) leads to greater improvement in VentE than by D. Thirty-eight obese children (10±0.2 years; BMI >95th percentile) were randomly divided into two study groups: D (n=17; BMI=30±1 kg/m 2 ) and DET (n=21; 28±1 kg/m 2 ). Ten lean children were included in a control group (10±0.3 years; 17±0.5 kg/m 2 ). All children performed maximal treadmill testing with respiratory gas analysis (breath-by-breath) to determine the ventilatory anaerobic threshold (VAT) and peak oxygen consumption (VO 2 peak). VentE was determined by the VE/VCO 2 method at VAT. Obese children showed lower VO 2 peak and lower VentE than controls (p 0.05). In contrast, the DET group showed increased VO 2 peak (p=0.01) and improved VentE (ΔVE/VCO 2 =−6.1±0.9; p=0.01). VentE is decreased in obese children, where weight loss by means of DET, but not D alone, improves VentE and cardiorespiratory fitness during graded exercise.