In competitive speed skating healthy athletes complain of subjective variants of exercise-induced bronchoconstriction such as coughing, chest tightness and excessive mucus production. This is especially so after a 1500 m race which can be considered as extremely strenuous. We compared peak expiratory flow (PEF) measurements 3, 10, 20, 60, 90 and 120 min after such a race with baseline, just before the race, in 10 adults in a competitive situation in Calgary (Canada) and The Hague (NL) and in 8 children in Utrecht (NL). A gradual decline in PEF was found, the mean decrease reaching significance (p < 0.05) at 10, 90 and 120 min in Calgary, at 90 and 120 min in The Hague and at 90 min in Utrecht for the children. The mean decrease over the whole period was significantly greater (3.6%, SEM 0.6%) in Calgary when compared with The Hague. The decrease could not be explained by the daily PEF variation that we measured in both groups. We conclude that there is a slight bronchoconstrictory effect, even in healthy athletes, when partaking in this strenuous type of exercise at low temperatures. An explanation may be the strong drying and temperature stimulus to the airways, stimulating vagal nerve activity, causing not only the cough and mucus production but also a gradually increasing minor bronchoconstriction.