THE BRONCHOCONSTRICTOR EFFECT OF STRENUOUS EXERCISE AT LOW-TEMPERATURES IN NORMAL ATHLETES

In competitive speed skating healthy athletes complain of subjective v ariants of exercise-induced bronchoconstriction such as coughing, ches t tightness and excessive mucus production. This is especially so afte r a 1500m race which can be considered as extremely strenuous. We comp ared 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 adul ts in a competitive situation in Calgary (Canada) and The Hague (NL) a nd 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 f or the children. The mean decrease over the whole period was significa ntly 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 w e measured in both groups. We conclude that there is a slight bronchoc onstrictory effect, even in healthy athletes, when partaking in this s trenuous type of exercise at low temperatures. An explanation may be t he 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.