The aim of this study was to assess the progression of bronchial reactivity (BR), incidence of bronchial hyperreactivity (BH), the exercise-induced bronchoconstriction (EIB), and asthma in triathletes over 2 years. Subjects included 7 athletes from the Swiss National Triathlon Team (age: 24.3±4.8 yrs), who initially were not asthmatics, not treated with anti-asthmatic medication, and who performed on the international level for over 3 consecutive years (2001-2003). To assess BR, BH, and EIB, subjects ran on a 400m track for 8 min at intensities of the anaerobic threshold. Tests were conducted in ambient temperatures of 4.4±2.8, -8.8±2.4 and 3.6±1.5°C, and humidity of 52±16, 83±13 and 93±2%. FEV1 was measured prior to, and at 2, 5, 10, and 15 min after EIB, and 5 min after inhalation of a β2-agonist. 2 methods were used to calculate the incidence: 1) the standard assessment and 2) extrapolation of the decrease in FEV1 to the BH limit. BR increased significantly in 7 athletes (FEV1: year p=0.04, year X EIB p=0.002, and EIB p<0.001). Within 2 years, BR increased significantly and even reached BH in some athletes. Three athletes exhibited BH at an increase of 22% each year. After extrapolating the decrease in FEV1 in all 7 athletes, the limit of 10% by definition for BH was determined to occur within 1.77 to 4.68 years, resulting in 21-57 % of athletes with newly developed BH per year. Thus, athletes developed EIB rather quickly, reflecting a rate increase 195-286 times above the normal rate for asthma.
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