Bronchial response to 6 min exercise performed as treadmill-walking, treadmill-running, ergometer bicycling and free running were compared in 11 subjects with exercise-induced asthma (EIA). The study was performed under control of air temperature and relative humidity. The three different types of exercise were performed on consecutive days, and the ventilation was monitored using pneumotachography and rating of perceived exertion (RPE). The decrease in peak expiratory flow after treadmill-running was 25.5 +/- 4.5% (mean +/- SEM), after bicycle ergometer exercise 26.0 +/- 3.0%, after treadmill-walking 26.0 +/- 3.0% and after free running 27.0 +/- 3.5%. No statistical difference in bronchial response was demonstrated between the four types of exercise. The total ventilation for the 6 min period of exercise was 421, 411 and 427 litres for treadmill-walking, treadmill-running and bicycle ergometer exercise, respectively. It is concluded that the type of work is of little importance in EIA.