Pulmonary function and airway responsiveness in young competitive swimmers.

Rationale: Strong physical activities are often associated with large lung volumes and relatively reduced flow, which may represent a physiological variant but also an obstructive abnormality. Competitive swimmers have also spirometric values even larger than other athletes, although they are at increased risk for asthma or airway hyperresponsiveness.

Aim: We aimed to investigate whether lung volumes increase with duration of swimming training and are related to an obstructive abnormality associated with airway hyperresponsiveness and asthma-like symptoms.

Methods: Forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC), airway responsiveness, and skin prick test were measured in 34 children/adolescents (age: 7-19 yrs old) trained for competitive swimming. Their "lifetime" exposure, i.e., the hours spent in pool was very strongly correlated with their age at the time of study. The effect of swimming activity was therefore estimated from the relationships between lung function data and age.

Results: FVC Z-score was positively correlated with age, indicating that absolute values increased more than expected with normal growth, but FEV(1)/FVC was negatively correlated with age. Although the majority of subjects had allergic sensitization to aeroallergens and about one half had asthma-like symptoms and/or airway hyperresponsiveness, these conditions did not alter the relationships between lung function and age.

Conclusion: Intense swimming activity may cause a greater than normal lung growth, irrespective of the presence of allergic sensitization or airway hyperresponsiveness. The associated reduction of FEV(1) /FVC may represent a physiological variant rather than a true obstructive abnormality.