Modifiable lifestyle factors impact airway health in non-asthmatic prepubescent boys but not girls

The prevalence of both childhood obesity and childhood asthma has increased dramatically over the past few decades. Little is known concerning the role of body composition and lifestyle influences on airway health in children. The aim of this study was to determine whether body composition, fruit and vegetable intake (FV) and physical activity (PA) impact airway health in healthy prepubescent children. Pulmonary function tests (forced expiratory flow in 1-sec, forced vital capacity, forced expiratory flow at 25-75% of vital capacity) and exhaled nitric oxide (eNO) were measured pre- and post-exercise in 40 healthy (20 boys, 20 girls), non-asthmatic prepubescent children (age 9.7 ± 0.8 years). PA and FV intake were assessed via questionnaire. Each participant completed an incremental cycle-ergometer exercise test to exhaustion (V0₂max). Body composition was measured via Dual Energy X-ray Absorptiometry. Participants were stratified by sex for analyses, and follow-up analyses were performed using a clinically significant drop in FEV₁ of ≥10% to divide participants into groups. In the overall group, the change in FEV₁ (pre- and post-exercise) was inversely related (r = -0.47, P < 0.05) to % body fat; participants with the highest body fat demonstrated the greatest decrease in FEV₁ (i.e., airway narrowing). When participants were divided by sex, this association held true only for boys (r = -0.61, P < 0.01). Percent body fat was the only significant contributor to the overall prediction of ΔFEV₁ in boys. Boys engaged in significantly more PA than girls (3.45 ± 2.39; 2.00 ± 1.30 activities/day). Boys also had significantly higher V0₂max adjusted for lean body mass than girls (48.06 ± 5.09; 42.30 ± 6.06). Body fat percent was not different by sex (P > 0.05). The participants in the ≥10% FEV₁ group had a significantly greater body fat (28.1 ± 9.6%) compared to the <10% drop group (18.8 ± 9.8%). These results suggest that PA, FV consumption, and body fat collectively impact airway health in prepubescent boys but not girls. Body fat, however, is the only independent predictor of post-exercise airway narrowing.