Mechanisms for Asthma in Athletes

The prevalence of asthma increased in athletes compared to the general population, especially among athletes within in endurance sports performed in the cold or in swimming pools. We know little about the causes of this. The purpose of the study is to examine how systematic endurance training affects the airways over time.


Formal title

Mechanisms for Asthma In athletes


The main objective of the study is to increase understanding of the mechanisms of
asthma in athletes through examining changes in the airways caused by endurance
training. Our hypothesis is that endurance athletes, with or without asthma
diagnosis, will show signs of epithelial damage and inflammation in the airways
compared with healthy controls. The secondary objective is to examine the
contributing pathogenic mechanisms for the development of asthma and bronchial
hyperresponsiveness in endurance athletes.


The project is based on three separate studies. The first study is a methodological study where measurements procedures for parasympathetic activity were compared in healthy adults.

The second study is a cross-sectional study and includes 3 groups: athletes with asthma, healthy athletes and healthy non-athletes. All participants made two visits to the laboratory at NSSS on two separate days. Measurements of lung function, bronchial hyperresponsiveness (BHR), allergy by skin prick tests, parasympathetic activity and airway inflammation by induced sputum were done.

The final study is a cross-sectional study where medical records of 150 elite athletes were examined and used to characterize asthma phenotypes based on clinical characteristics.

Cooperating partners: University in Porto, Portugal.


In the first study (Paper 1), no agreement between the measurements procedures (Heart rate variability (HRV) and pupillometry) were found. Furthermore, no association between parasympathetic activity measured in the heart nor the pupil and reversibility to inhaled ipratropium bromide (ΔFEV1), and anti-cholinergic bronchodilator, were found (Paper 1:

The results from second study (Paper 2 and 3) showed an inverse association between BHR to methacholine (PD20) and HRV, but not pupillometry. Furthermore, these associations were stronger in swimmers than as compared to non-athletes, irrespective of asthma diagnosis. In addition, severe BHR was more frequently found in swimmers than in cross-country skiers. Evidence of airway inflammation was found in both athletes groups compared to non-athletes. Thus, airway inflammation and BHR is present in both asthmatic and healthy athletes compared to non-athletes (Paper 2:, paper 3 in progress).

The results of study 3 (Paper 4) revealed two asthma phenotypes in athletes; "atopic asthma" and "sport asthma". Increased risk of "sport asthma" was found among water sport athletes and winter sport athletes as compared to land based athletes (Paper 4: