Swimming and asthma: factors underlying respiratory symptoms in competitive swimmers

Swimming is recommended for asthmatics. However, many competitive swimmers report asthmatic symptoms. While some studies identify the swimming environment as a trigger for allergy and asthmatic symptoms, even more studies suggest swimming to be suitable for people with allergies and asthma. The factors behind the symptoms were studied first by determining the prevalence of asthma, allergy and self-reported asthmatic symptoms in experienced Finnish swimmers and then by examining the relationships between the reported symptoms and the main triggering factors: medical history, environment and exercise intensity.

Top swimmers (n = 332) of the Finnish Swimming Association registry (N = 4578) were asked to complete a structured questionnaire on their medical history, swimming background, swimming environment and symptoms in different swimming intensities. Two hundred experienced swimmers, 107 females and 93 males, with an average age of 18.5 [standard deviation (SD) = 3.0] years and a swimming training history of 9 (SD = 3.8) years completed the questionnaire.

Physician-diagnosed asthma was reported by 32 swimmers (16%), including 24 (12%) with exercise-induced asthma. Physician-diagnosed allergy was reported by 81 (41%) swimmers. Asthmatic symptoms during swimming were described by 84 subjects (42%). Most symptoms occurred when swimming exceeded speeds corresponding to the lactic/anaerobic threshold. Family history of asthma was significant and the most important risk factor for asthmatic symptoms.

The prevalence of asthma in swimmers was higher than in the general population but not different from that in other endurance athletes. Family history of asthma and increased swimming intensity had the strongest associations with the reported asthmatic symptoms.