Adverse respiratory health effects of competitive swimming: the prevalence of symptoms, illnesses, and bronchial responsiveness to methacholine and exercise
Creators: name: Potts, James Edward
Publisher: name: University of British Columbia
Year: 2009

description: Indoor swimming pools, with their high ambient temperatures and relative humidity, contain a number of volatile chemicals that are known irritants, sensitizing agents, and possible carcinogens. While swimming may improve fitness and reduce morbidity associated with asthma, there is both anecdotal and scientific information to suggest that there are health-related problems associated with swimming in chemically-treated pool water. Competitive swimmers are especially susceptible to the adverse effects of chemically-treated pool water because of the number of hours they spend training in this environment and the increase in ventilation that occurs with exercise. While case reports of respiratory and other health-related problems are common, there have been no epidemiological studies that have surveyed competitive swimmers about the prevalence of health-related problems or the prevalence and severity of clinical symptoms. The purpose of this study was to determine the prevalence of respiratory and other healthrelated symptoms, illnesses, and allergies among competitive swimmers using a questionnaire, and to establish whether the symptoms were associated with swimming-related exposure. In order to determine how these symptoms and illnesses manifest themselves clinically, a group of lower mainland swimmers and non-swimmers also completed pulmonary functions studies, a methacholine challenge test, and exercise studies in the laboratory and swimming pool. Our results show that competitive swimmers have a high prevalence of asthma that, in national and international level swimmers, appears to have developed after they began competitive swimming. There was also a high prevalence of exercise-related respiratory symptoms that were strongly associated with swimming-related exposure. Nearly all of the competitive swimmers had normal pulmonary function tests, however, 60% of the swimmers were found to have increased non-specific bronchial responsiveness (BHR) to methacholine. There was no difference in the prevalence of BHR among swimmers with or without asthma and/or exercise-related symptoms, however, the prevalence of BHR was significantly higher in swimmers than in non-swimmers. The prevalence of exercise-induced asthma (ETA) was higher running or cycling in the laboratory than during tethered swimming in the pool. There was no difference in the prevalence of ETA among swimmers and non-swimmers during the laboratory testing. These results suggest that swimming related exposure, as determined by the amount of time spent swimming or the distance covered during training sessions in the swimming pool, increases non-specific bronchial responsiveness without affecting baseline pulmonary function or short-term exercise responses. Longer exposures may lead to the development of upper and lower respiratory tract symptoms, and the adoption of a restrictive breathing pattern in susceptible individuals. We propose that differences in the clinical presentation of these competitive swimmers may be dependent on the presence of atopy, underlying respiratory illnesses such as asthma, the pre-existing level of bronchial responsiveness, and the extent of the swimming-related exposure. It is possible that chronic, low level exposure to the chemicals used to disinfect swimming pool water may, ultimately, be responsible for our clinical and exercise related findings.