Strenuous physical activity at an elite level is associated with an increased risk for asthma and, in some sports, also prevalence of allergies. The

We found a high prevalence of asthma among elite swimmers and tennis players and a higher frequency of current asthma and positive mannitol challenge tests among the swimmers. This indicates an unfavorable exercise environment.

One hundred and one adolescent swimmers and 86 tennis players answered a questionnaire about respiratory symptoms and allergy and performed mannitol challenge and sport-specific exercise challenge. Atopy was assessed and fractional exhaled nitric oxide was measured. Mannitol positivity was defined as drop in FEV1 ≥15% (ordinary criteria) and/or β2-reversibility (≥15%) after provocation (extended criteria). A positive exercise test was defined as a drop in FEV1 ≥10% (ordinary criteria) and/or β2-reversibility (≥15%) after provocation (extended criteria). Club cell protein (CC16) was measured in urine before and after the challenges.

Asthma symptoms were common in both groups. More swimmers had exercise-induced symptoms (77% versus 50%) and current asthma symptoms (56% versus 38%), compared to the tennis players. More swimmers also had a positive mannitol challenge test both using ordinary (26% versus 6%) and extended criteria (43% versus 17%), while the number of positive exercise tests did not differ. After exercise (but not mannitol) challenge, CC16 level was increased in both groups, but to a higher extent in tennis players. There were no differences in atopy, rhinitis or fractional exhaled nitric oxide.