Problems of interpreting exercise-induced asthma

Abstract

Abstract Factors affecting exercise-induced asthma are reviewed based on studies in large numbers of children and young adults. Evidence is presented to show that running is a more potent and reproducible stimulus than cycling and that walking and swimming have a small and variable effect. The greatest amount of exercise-induced asthma is found after 6 to 8 minutes of steady-state running at a work rate equivalent to about two thirds of the working capacity of the subject. Exercise may be repeated every 2 hours throughout the day without any diminution of its effect in causing postexercise bronchoconstriction. The use of exercise in assessing drugs used to treat asthma is discussed, and the importance of the type of exercise test and the use of placebo preparations is emphasized. Serial exercise tests may be used to study the duration of protection from exercise-induced asthma afforded by drugs such as cromolyn sodium.