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). After interventions, all obese children reduced body weight (p<0.05). D group did not improve in terms of VO (2) peak or VentE (p>0.05). In contrast, the DET group showed increased VO (2) peak (p=0.01) and improved VentE (DeltaVE/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.