3.2 Allergic rhinitis
Allergic inflammation is the most common cause of chronic rhinitis and responsible for inducing nasal symptoms after allergen exposure in a sensitized individual through an IgE-induced pathway30. A recent systematic review mentions a prevalence of AR in athletes ranging from 21 to 56.5 % 31 which is comparable to the prevalence in the general population. When looking at specific sports populations however, aquatic athletes seem to suffer more frequently from AR compared to land-based athletes32. This might be explained by the fact that chlorination products might predispose to allergic sensitization33, however, this could not be confirmed by in vivo 34 nor in vitro 5studies. It has been suggested that strenuous exercise may contribute to the development of allergic sensitization after showing a potential shift of the T-lymphocyte population towards a T helper 2 subtype upon excessive exercise 35, 36. To our knowledge, no study has demonstrated a causal relationship between exercise and allergic sensitization.