High-intensity training improves airway responsiveness in inactive nonasthmatic children : evidence from a randomized controlled trial

Purpose: the relationship between physical activity and airway health in children is not well understood. The purpose of this study was to determine whether 8 wk of high-intensity exercise training would improve airway responsiveness in prepubescent, nonasthmatic, inactive children. Methods: 16 healthy, prepubescent children were randomized [training group (TrG) n = 8, control group (ConG) n = 8]. Prior to and following 8 wk of training (or no training), children completed pulmonary function tests (PFTs): forced expiratory volume in 1 s (FEV 1), forced vital capacity (FVC), forced expiratory flow at 25- 75% of vital capacity (FEF 25-75), and exhaled nitric oxide (FENO). Children completed an incremental cycle VO 2maxtest, eucapnic voluntary hyperventilation (EVH), anthropometric tests, and blood tests to determine fasting blood glucose, total cholesterol, HDL, LDL, and triglycerides. Body fat percentage was determined using dual-energy X-ray absorptiometry pretraining and bioelectrical impedance preand posttraining. Results: there were no differences (P > 0.05) in anthropometric measures or PFTs between TrG and ConG at baseline. In the TrG, there was a significant increase in VO 2max (∼24%) and a decrease in total cholesterol (∼13%) and LDL cholesterol ∼35%) following training. There were improvements (P > 0.05) in ΔFEV 1 both postexercise (pre: -7.60 ± 2.10%, post: -1.10 ± 1.80%) and post-EVH (pre: -6.71 ± 2.21%, post: -1.41 ± 1.58%) with training. The ΔFEF 25-75pre-post exercise also improved with training (pre: -16.10 ± 2.10%, post: -6.80 ± 1.80%; P < 0.05). Lower baseline body fat percentages were associated with greater improvements in pre-post exercise ΔFEV 1 following training (r = -0.80, P < 0.05). Conclusion: these results suggest that in nonasthmatic prepubescent children, inactivity negatively impacts airway responsiveness, which can be improved with high-intensity training. Excess adiposity, however, may constrain these improvements.