RESUMEN
BACKGROUND: Exercise is one of the most common precipitating factors of acute asthmatic crises in childhood. Although it has been described as more frequent among children, this is probably due to their more abundant physical activity. Nevertheless, it also occurs at other ages. OBJECTIVE: The aim of this study is to assess possible differences in postexercise spirometry after treadmill and free running provocation tests. METHODS: We compared the results obtained in a treadmill test performed by 30 asthmatic children and 30 healthy children with the results obtained with these same children in a free running test, keeping similar environmental conditions (temperature and humidity), exercise intensity (assessed by heart rate), and airway status at the time of the test. RESULTS: Seventy-three percent of the patients had positive treadmill tests and 63.3% had positive free running tests. For the spirometric parameters studied, there were no significant differences in the percent decrease in postexercise performance after either of the provocation tests. For FEV1, which is the most sensitive diagnostic parameter, the sensitivity was 53.3% in treadmill running and 56.7% in free running, with a specificity of 100% in both tests. CONCLUSIONS: If environmental conditions, exercise intensity, and airway status are controlled at the time of the test, treadmill and free running can be used indistinctly as asthma-inducing exercises.