Prevalence of exercise-induced bronchoconstriction in adolescent cross-country skiers using exercise challenge test in sub-zero air.

<bold>Background:</bold> Exercise-induced bronchoconstriction (EIB) is defined as a transient airway obstruction during, or shortly after, exercise. It is characterized by a decrease (≥10%) in forced expiratory volume during one second (FEV1). EIB is common among elite skiers, even among athletes without physician-diagnosed asthma. There are few studies using exercise test in sub-zero air to study EIB in elite skiers. <bold>Aim:</bold> To examine the prevalence of EIB in elite skiers using exercise test in sub-zero air. <bold>Methods:</bold> The 31 participants (16 women) were a random selection of the 175 cross-country skiers and biathletes from the Swedish national elite sport schools previously recruited to participate in the parent survey study about airway symptoms, exercise, and asthma. Six (19%) participants reported asthma medication usage for physician-diagnosed asthma during the last 12 months. Participants performed an exercise challenge in an environmental chamber (8 min running in -15 °C, Rh 77%, 85% of estimated maximum heart rate) with spirometry before and 5 to 30 minutes after. <bold>Results:</bold> EIB was detected in 7 (23%) of the 31 athletes, 5 of the 25 participants without asthma and 2 out of the 6 with asthma. Sex, age, training hours, allergy, FeNO, and prevalence of wheezing with dyspnea during the last 12 months did not differ between athletes with and without EIB. <bold>Conclusion:</bold> Exercise challenge in a sub-zero environment demonstrated a high prevalence of EIB in adolescent Swedish cross-country skiers, irrespective of asthma diagnosis and symptoms of wheezing with dyspnea.