Reproducibility of exercise-induced asthma in children.

The reproducibility of exercise-induced asthma (EIA) was studied in children with perennial asthma, using treadmill exercise challenge tests repeated at mean intervals of 1 week (Group I, n = 20), 1 month (Group II, n = 20) and 1 year (group III, n = 18). The protocol was standardized with respect to intensity and duration of exercise, time of last medication prior to exercise, air humidity, use of corticosteroids, asthma attacks, and 6) pollen season. The mean percentage fall in peak expiratory flow (PEF) following exercise remained significantly unchanged in the three groups. The reproducibility of EIA was improved compared with previous studies. Although the random variation of EIA tended to be greater in Group III, the individual severity of EIA was remarkably stable whatever the interval between tests. Improvements in baseline airway function between tests were not followed by a simultaneous decrease in EIA. In conclusion, the severity of EIA is reproducible in children with perennial asthma, when the exercise protocol is standardized for factors known to influence bronchial reactivity.