CHAPTER 1 Epidemiology of asthma, allergy and bronchial hyperresponsiveness in sports T. Haahtela*, K. Larsson # , S. Bonini } *Dept of Allergy, Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland, # Unit of Lung and Allergy Research, National Institute of Environmental Medicine, IMM Karolinska Insitituet, Stockholm, Sweden. } IRCCS San Raffaele, Rome, and Second University of Naples, Naples, Italy. Correspondence: T. Haahtela, Dept of Allergy, Skin and Allergy Hospital, Helsinki University Central Hospital, FIN-00250 Helsinki, Finland. Fax: 385 947186500 E-mail: tari.haahtela@hus.fi Asthma has a higher prevalence in athletes compared with the general population. In summer sport events, the prevalence ranges 3.7–22.8%, as reviewed by Helenius and Haahtela [1]. In winter sport events, the occurrence is even higher, ranging 2.8–54.8% (table 1) [2–8]. A total of 17% of 253 Finnish elite summer sport athletes used asthma medication, most commonly inhaled b2-agonists [1]. Also, 17% of the USA Winter Olympic Team (Nagano, Japan) were current users of asthma medication [5], while the figure was twice as high (36%) amongst Swedish cross-country skiers [2]. In a Swedish study in upper secondary schools for young skiers, 15% had phsysician-diagnosed asthma and 18% were treated with anti-asthma drugs compared with 6% and 7%, respectively, amongst the controls [9]. Occurrence of bronchial hyperresponsiveness Bronchial hyperresponsiveness (BHR) is correlated with clinical asthma symptoms, but the relationship is not straight forward. Larsson et al. [2] observed that 23 out of 42 (54.8%) cross-country skiers had BHR and asthma symptoms. Two skiers had BHR without symptoms and 17 had symptoms, but no BHR. Leuppi et al. [7] found that 35% of Swiss ice hockey players had BHR, but clinical asthma was diagnosed in 19% and exercise-induced bronchospasm (EIB) in 11% of them. The respective figures for BHR, clinical asthma and EIB were lower in floor ball players: 21%, 4.2% and 4.2%. Sue-Chu et al. [3] reported that in cross-country skiers the figures for BHR and clinical asthma were closer to each other: 14% and 12% in Norway, and 43% and 42% in Sweden, respectively. Karjalainen et al. [10] studied 40 young elite skiers and 12 healthy control subjects. BHR to methacholine was found in 30 (75%) of the skiers, and one-third of them had symptoms suggestive of asthma. BHR is also prevalent in swimmers. Zwick et al. [11] found competitive swimmers to have BHR significantly more often than control subjects (78% versus 36%). In another study, BHR was detected in 60% of swimmers and in 12% of nonswimming athletes [12]. The prevalence of BHR was higher in swimmers (36%) than in speed and power athletes (18%) and in long-distance runners (9%) [13]. A "healthy runner effect" certainly takes place, especially in long-distance runners. BHR was significantly associated with atopy. Conclusions of the associations are problematic in cross-sectional studies because dynamic variables fluctuate over time depending on various factors. Heir et al. [14] observed that acute respiratory tract infections were associated with a transient increase Eur Respir Mon, 2005, 33, 1–4. Printed in UK - all rights reserved. Copyright ERS Journals Ltd 2005 European Respiratory Monograph ISSN 1025-448x. ISBN 1-904097-22-7. 1