in BHR in athletes performing physical training, but not in nonactive control subjects. Exercise and breathing cold air causes transient BHR even in asthmatic nonathletes [15, 16]. Occurrence of eosinophilic airway inflammation Asthma symptoms and lung function abnormalities, including BHR, are a consequence of airway inflammation, which in asthma is predominately of an eosinophilic type. However, in athletes a mixed type of eosinophilic and neutrophilic airway inflammation has been shown to affect ice hockey players, cross-country skiers and elite swimmers [8, 10, 17]. Sputum eosinophilia (w2% of the differential cell count) affected one-fifth of highly trained swimmers [17, 18] and one-tenth of ice hockey players [8]. Those swimmers with exercise-induced bronchial symptoms had significantly higher sputum eosinophil cell counts (mean 7.6%) than the symptom-free swimmers (mean 0.7%) [17]. After 5-yr follow-up, sputum eosinophilia was detected in 38% (6% at baseline) of those swimmers who continued their active career, and in 8% (19% at baseline) of those who had stopped intensive training [18]. Karjalainen et al. [10] showed that the number of activated eosinophils, T- lymphocytes and macrophages in the subepithelial tissue are much higher in cross- country skiers than in sedentary control subjects. Elite swimmers have shown increased concentrations of eosinophil peroxidase (EPO) and human neutrophil lipocaline (HNL) in the supernatant of induced sputum samples as compared with control subjects, which suggests that both eosinophils and neutrophils are more activated in swimmers than in controls [17]. Type of training as a risk factor Highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many inhalant irritants and allergens all year long. The type of training has been associated with the occurrence of bronchial symptoms, BHR and asthma in elite athletes [13, 19]. Table 1. – Prevalence of asthma amongst highly trained winter sports athletes Group of athletes Subjects n Method Prevalence % First author [Ref.] Cross-country skiers 42 Questionnaire, spirometry, methacholine challenge 54.8 LARSSON [2] Cross-country skiers 171 Questionnaire, spirometry, methacholine challenge 12 (Norway) SUE-CHU [3] 42 (Sweden) Figure skaters 124 Exercise test 35 (exercise-induced bronchospasm) MANNIX [4] Ice hockey players # Questionnaire, spirometry, methacholine challenge, exercise test 19.2 LEUPPI [7] 11.5 (exercise-induced bronchospasm) Ice hockey players 88 Questionnaire, spirometry, histamine challenge 22 (total asthma) LUMME [8] 13 (current asthma) 1998 USA Winter Olympic team 196 Questionnaire 21.9 WEILER [5] 60.7 (cross-country, etc.) 24 (alpine, etc.) 2.8 (bobsleigh, etc.) 1998 USA Winter Olympic team # Exercise challenge, spirometry 23 (all, exercise-induced bronchospasm) WILBER [6] 50 (cross-country) # : Source population n=196. T. HAAHTELA ET AL. 2