Elite Swimmers Have Larger Lung Volumes But More Severe Bronchial Hyperresponsiveness Than Elite Cross Country Skiers

Abstract

A few previous reports have shown that lung volumes, diffusion capacity as well as bronchial hyperresponsiveness (BHR) are increased in well trained swimmers as compared to other athletes and controls. It is unknown if this can be applied to elite athletes and if this is due to genetic or environmental factors such as the specificity of the swim training and the exposure to chlorine derivatives in the swimming pools. PURPOSE: To compare lung function, BHR and respiratory symptoms in elite swimmers and cross country skiers. METHODS: In a cross sectional study, 29 elite swimmers (17♂/12♀) aged 16–28 years and 30 elite cross-country skiers (20♂/10♀) aged 20–37 years, all competing at high international level, measured lung function by maximal expiratory flow volume loops, forced expiratory flow the first second (FEV1), forced vital capacity (FVC), forced expiratory flow at 50 % of FVC (FEF50) and bronchial hyperresponsiveness was measured by methacholine provocation test, provocation dose at 20 % reduction in FEV1 (PD20meth). Training time per week, symptoms and use of antiasthmatic medication were recorded with the AQUA-questionnaire and by a clinical examination. Antiasthmatic medication was withheld according to ERS guidelines. RESULTS: The elite swimmers had a significant higher FEV1, as compared to the cross country skiers, 4.73L (4.39, 5.07) mean (95 % confidence interval) vs 4.31L (4.06, 4.57) (p=0.05) respectively, FEV1 (% predicted), 114.7 % (110.2, 119.2) vs 103.0 % (99.2, 106.7) (p<0.001) respectively and FVC (% predicted), 122.4 % (116.9, 127.8) vs112.2 % (108.4, 115.9) (p=0.002) respectively. Twenty-three swimmers had a PD20meth ≤ 4 umol as compared to six cross country skiers. Mean training time per week was significant higher in swimmers, 23.8 hours (23.1, 24.4) vs 17.1 hours (16.6, 17.6) (p< 0.001). 27.6 % of the swimmers and 70 % of the skiers had an asthma diagnosis and 37.9 % of the swimmers and 83.3 % of the skiers used daily antiasthmatic medication. No differences were found in the other lung function variables or in self-reported symptoms. CONCLUSION: Elite swimmers have larger lung volumes and FEV1 than elite cross country skiers, but it seems that swimmers are more likely to develop severe BHR due to exposure to chlorine derivatives during their prolonged daily training sessions.