Exercise intolerance in obese children and adolescents

Background: Abnormal lung function has been reported in the obese population and is associated with the severity of obesity.

Objectives: To identify abnormal lung function in obese children and adolescents, and examine the cardiopulmonary response of those who have abnormal lung functions during exercise, and to reveal predictors of exercise intolerance in this population.

Methods: Fifty obese participants aged 8–18 years (56% male; mean age 13.2 ± 2.0 years; mean BMI 33.0 ± 3.6 kg/m², mean BMI z score 3.1 ± 0.3) underwent spirometry, lung volume evaluation, and a cardiopulmonary exercise test.

Results: Lung function abnormalities and exercise intolerance because of pulmonary limitations were found in 36% and 74% of the participants, respectively. A comparison of participants with normal and abnormal lung functions revealed a lower breathing reserve and a higher ventilatory equivalent for CO₂ production (V_E/VCO₂) during exercise in those who had lung function abnormalities (18 ± 15 vs 30±10%, P <0.001 and 30.3 ± 3.3 vs 29.6 ± 3.1; P = 0.02, respectively). Exercise intolerant participants had a higher BMI z score compared with those who were not (3.1 ± 0.3 vs 2.9 ± 0.3; P = 0.03). BMI z score ≥ 2.84 had an 80% sensitivity and 67% specificity for predicting exercise intolerance in this population.

Conclusions: Evaluations of lung function and exercise capacity should be included in the follow-up planning for obese children and adolescents. A BMI z score ≥ 2.84 was most sensitive for predicting exercise intolerance in this population.