Respiratory Symptoms and Bronchial Responsiveness in Competitive Swimmers

STADELMANN, K., T. STENSRUD, and K.-H. CARLSEN. Respiratory Symptoms and Bronchial Responsiveness in Competitive Swimmers. Med. Sci. Sports Exerc., Vol. 43, No. 3, pp. 375-381, 2011. Purpose: A high prevalence of bronchial hyperresponsiveness (BHR) and respiratory symptoms has been reported among competitive swimmers. From the 2002 Winter Olympics, BHR measurements or bronchodilator reversibility have been required for approved use of beta(2)-agonists in sports. The first aim of this study was to evaluate the relationship among respiratory symptoms in young elite swimmers, eucapnic voluntary hyperpnea (EVH), and the inhaled dose of methacholine, causing a 20% decrease in forced expiratory volume in 1 s (FEV1; PD20 (methacholine)). The second aim of this study was to assess the repeatability of the EVH test. Methods: For this study, 15 male and 9 female adolescent elite swimmers, aged 15 to 25 yr, performed one PD20 (methacholine) test and two EVH tests in a randomized order. Dry air containing 5% CO2 was inhaled for 6 min with a target ventilation of >= 85% of maximum voluntary ventilation (minimum = 65%). PD20 methacholine <= 2 mu mol and EVH with FEV1 reduction >= 10% were considered positive. Respiratory symptoms and medication were reported in the modified AQUA(2008) questionnaire. Results: Twenty swimmers (83%) reported respiratory symptoms, 13 ( 65%) of them had a positive provocation test. Fourteen (58%) had at least one positive test to either EVH or PD20 methacholine; three had only one positive EVH test. One athlete had BHR without symptoms. The sensitivity of PD20 methacholine <= 2 mu mol for respiratory symptoms was 50% versus 60% and 47.37% for the two EVH tests, respectively, and 75% for PD20 methacholine <= 4 mu mol. The Bland-Altman plot of the two EVH tests showed a consistent distribution, with only one subject outside the limits of agreement. Conclusions: BHR was frequently found among adolescent competitive swimmers. PD20 methacholine <= 2 mu mol and EVH >= 10% compared well, but PD20 methacholine <= 4 mu mol had the highest sensitivity for respiratory symptoms. The EVH test has high repeatability but is very expensive and uncomfortable to perform.