Reducing Exercise-induced Bronchoconstriction in Children With Asthma and Obesity

Note related to early termination: Although the intent of the study was to compare obese and nonobese children, early termination precluded us from completing this analysis and thus the pooled results are included in the results. The brief summary has been updated to reflect the presented results. The investigators will enroll prepubescent, 8 - 12 yr old, obese (body mass index \> 95th percentile; N=25) and nonobese (body mass between 16th and 84th percentile; N=25) children with mild asthma. The investigators will investigate the severity of exercise-induced bronchoconstriction during planned exercise performed 15 minutes after the following three conditions performed on separate days in a random order: (1) 8x30sec interval warm-up, (2) short-acting beta agonist or albuterol, \& (3) control, in prepubescent, 8 - 12 yr old, obese and nonobese children with mild asthma. The investigators will measure the following in all participants: 1. Pulmonary function: spirometry, lung volumes, diffusing capacity of lung for carbon monoxide, maximum voluntary ventilation, maximal inspiratory and expiratory pressures, airway resistance, and expired nitric oxide 2. Exercise tolerance during graded cycle ergometry: Gas exchange, ventilation, heart rate, blood pressure, pulse oximetry, electrocardiogram 3. Ratings of perceived breathlessness and exercise induced bronchoconstriction in response to a 6 minute high-intensity exercise challenge after three conditions performed on three separate days: Three conditions that will precede the exercise challenge include: 1. 8x30sec of interval warm-up 15min prior to exercise challenge: This includes eight 30sec bouts of high-intensity interval exercise at 85-95% of HRmax, with 45sec of recovery between. 2. Two puffs of albuterol 15 min prior to exercise challenge 3. Control: seated rest for 15min prior to exercise challenge Control visit was always completed first. The order of the albuterol and interval warm-up exercise visits was randomized.