Prévalence et mécanismes de développement de l'asthme et de l'hyperréactivité bronchique chez les athlètes

Asthma is a common disease among athletes and an increased incidence has been widely reported in the last decades; still, little is known about the possible mechanisms responsible for the development of asthma and also airway hyperresponsiveness (AHR) in athletes. The relationship between the regular practice of high-intensity exercise and asthma, and/or AHR in athletes remains to be determined. The objectives of this doctoral program are therefore to study the relationships between the prevalence of AHR and asthma in athletes, and also between the perception of respiratory symptoms induced by exercise and AHR. We also documented the prevalence of asthma among athletes of the Province of Quebec. We then explored some of the mechanisms that could lead to the development of AHR in athletes.

A comparative review on the prevalence of AHR and asthma illustrates the discrepancy that exists between the prevalence of those two conditions. We then propose some hypothesis to explain this discrepancy. Variations in the perception of respiratory symptoms during exercise may contribute to this phenomenon. Over-expression of asymptomatic AHR might also contribute to the discrepancy. We were able to determine that the record of respiratory symptoms related to exercise has a limited usefulness in the detection of AHR but that nociceptive sensations perceived during exercise are a more reliable predictor of AHR in athletes, as observed in sedentary subjects.

Through a province-wide survey reaching close to 1500 athletes, we were able to document the prevalence of asthma among athletes of the Province of Quebec and make a comparative analysis of that prevalence in four groups of athletes classified according to the predominant type of air inhaled during training.

By analyzing the differential inflammatory cell count and the total cell count in the induced sputum, we observed that a training session could not induce a significant inflammatory airway response in swimmers and runners (with or with AHR). Finally, we observed a weak but significant relationship between sympatho-vagal tone and the degree of airway responsiveness in both athletes and sedentary controls.