Respiratory symptoms, bronchial responsiveness, and cellular characteristics of induced sputum in elite swimmers

To investigate respiratory symptoms, increased bronchial responsiveness, and signs of airway inflammation in elite swimmers, we examined 29 swimmers from the Finnish national team and 19 healthy control subjects (nonasthmatic, symptom-free). They answered a questionnaire and were interviewed for respiratory symptoms. Lung volumes were measured and bronchial responsiveness assessed by a histamine challenge test. Induced sputum samples were also collected. Fourteen (48%) of the swimmers and three (16%) of the control subjects showed increased bronchial responsiveness (P<0.05). The sputum cell differential counts of eosinophils (mean 2.7% vs 0.2%) and neutrophils (54.7% vs 29.9%) from swimmers were significantly higher than those from controls (P<0.01). Eosinophilia (sputum differential eosinophil count of >4%) was observed in six (21%) of the swimmers and in none of the controls (P<0.05). Symptomatic swimmers had significantly more sputum eosinophils than did the symptom-free. The concentrations of sputum eosinophil peroxidase (EPO) and human neutrophil lipocalin (HNL) were significantly higher in swimmers than control subjects (P<0.001 and P=0.05). We conclude that elite swimmers had significantly more often increased bronchial responsiveness than control subjects. Sputum from swimmers contained a higher percentage of eosinophils and neutrophils, and higher concentrations of EPO and HNL than sputum from controls. Long-term and repeated exposure to chlorine compounds in swimming pools during training and competition may contribute to the increased occurrence of bronchial hyperresponsiveness and airway inflammation in swimmers.