Weight Loss Associated with Exercise Training Restores Ventilatory Efficiency in Obese Children

Abstract

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/m²) and DET (n=21; 28±1 kg/m²). Ten lean children were included in a control group (10±0.3 years; 17±0.5 kg/m²). All children performed maximal treadmill testing with respiratory gas analysis (breath-by-breath) to determine the ventilatory anaerobic threshold (VAT) and peak oxygen consumption (VO₂ peak). VentE was determined by the VE/VCO₂ method at VAT. Obese children showed lower VO₂ 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 VO₂ peak or VentE (p>0.05). In contrast, the DET group showed increased VO₂ peak (p=0.01) and improved VentE (ΔVE/VCO₂=−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.

Key words

childhood obesity - physical activity - ventilatory response - cardiorespiratory fitness

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Correspondence