Gas exchange during exercise in obese children

Twenty-three obese children, aged 9 to 14 years, ranging in percentage overweight from 26% to 83% (median 51.6%±16.3%), and 37 normal-weight children, matched for sex, age and height, performed a maximal exercise test on a treadmill. Cardiorespiratory performance was assessed by determination of the ventilatory anaerobic threshold (VAT) expressed in ml O₂/min per kg and as a percent of maximal oxygen uptake (% VO₂max). VAT and VO₂max related to body weight were significantly lower (P<0.01) in the obese than in the normal-weight children. VAT % VO₂max was similar in the two groups. A significant correlation was found between VAT and VO₂max both in the obese (r=0.85) and in the control groups (r=0.79). The habitual level of physical activity was lower in the obese subjects compared to the control subjects (P<0.001). In conclusion our study shows that physical fitness of overweight children is quantitatively lowered and that it can be assessed by VAT. VAT does not require a maximal test and is particularly useful in the ergometric study of subjects with exercise intolerance.Abbreviations AT anaerobic threshold - HR heart rate - VAT ventilatory anaerobic threshold - VCO₂ carbon dioxide output - VE ventilation - VO₂ oxygen uptake - VO₂max maximal oxygen uptake