High incidence of exercise-induced bronchoconstriction in triathletes of the Swiss national team

Aim: To assess the progression of bronchial reactivity (BR) and incidence of bronchial hyperreactivity (BH), exercise-induced bronchoconstriction (EIB) and asthma in triathletes over 2 years. Methods: Subjects were seven athletes from the Swiss national triathlon team (mean (SD) age 24.3 (4.8) years), who initially were not asthmatic, not treated with antiasthmatic medication, and who had performed at international level for more than 3 consecutive years (2001-2003). To assess BR, BH and EIB, subjects ran on a 400 m track for 8 min at intensities equal to the anaerobic threshold. Tests were conducted in ambient temperatures of 4.4 (2.8)degrees C, -8.8(2.4)degrees C and 3.6 (1.5)degrees C, and humidity of 52 (16)%, 83 ( 13)% and 93 ( 2)%. Forced expiratory volume in 1 s (FEV1) was measured before and at 2, 5, 10 and 15 min after EIB, and 5 min after inhalation of a beta 2 agonist. Two methods were used to calculate the incidence: (1) the standard assessment; ( 2) extrapolation of the decrease in FEV1 to the BH limit. Results: BR increased significantly in the seven athletes (FEV1: year, p = 0.04; year x EIB, p = 0.002; EIB p < 0.001). Within 2 years, BR had increased significantly and even reached BH in some athletes. Three athletes exhibited BH. After extrapolation of the decrease in FEV1 in all seven athletes, the limit of 10% by definition for BH was determined to occur within 1.77-4.81 years, resulting in 21-57% of athletes with newly developed BH per year. Conclusion: Athletes develop EIB quickly, a rate of increase 195-286 times that of the normal rate for development of asthma.