Mechanisms of asthma in Olympic athletes – practical implications

Abstract

Athletes’ symptoms may only occur in extreme conditions, which are far from normal. Exercise may increase ventilation up to 200 l/min for short periods in speed and power athletes, and for longer periods in endurance athletes such as swimmers and cross‐country skiers. Increasing proportions of young athletes are atopic, i.e. they show signs of IgE‐mediated allergy which is, along with the sport event (endurance sport), a major risk factor for asthma and respiratory symptoms. Mechanisms in the etiology and clinical phenotypes vary between disciplines and individuals, and it may be an oversimplification to discuss athlete’s asthma as a distinct and unambiguous disease. Nevertheless, the experience on Finnish Olympic athletes suggests at least two different clinical phenotypes, which may reflect different underlying mechanisms. The pattern of ‘classical asthma’ is characterized by early onset childhood asthma, methacholine responsiveness, atopy and signs of eosinophilic airway inflammation, reflected by increased exhaled nitric oxide levels. Another distinct phenotype includes late onset symptoms (during sports career), bronchial responsiveness to eucapnic hyperventilation test, but not necessarily to inhaled methacholine, and a variable association with atopic markers and nitric oxide. A mixed type of eosinophilic and neutrophilic airway inflammation seems to affect especially swimmers, ice‐hockey players, and cross‐country skiers. The inflammation may represent a multifactorial trauma, in which both allergic and irritant mechanisms play a role. There is a significant problem of both under‐ and overdiagnosing asthma in athletes and the need for objective testing is emphasized. Follow‐up studies are needed to assess the temporal relationship between asthma and competitive sporting, taking better into account individual disposition, environmental factors (exposure), intensity of training and potential confounders.

Swimming pool, respiratory health, and childhood asthma: Should we change our beliefs?

“…34 In fact, both in training and in competitions, their ventilation increases considerably (up to 200 L/min in adults), leading to aspiration of water droplets and inhalation of large amounts of air floating just above the water surface and therefore rich in chlorine by-products, which may be responsible for lung damage and respiratory symptoms. 35 Noteworthy, a recent study demonstrates that adolescent elite swimmers at the beginning of their careers do not show major differences from adolescents not involved in competitive swimming in terms of prevalence of respiratory symptoms, airway responsiveness, or airway inflammation 36 , suggesting that elite swimmers do not have particularly susceptible airways when they take up competitive swimming. The follow-up of this group of young athletes might be important to prove that the development of respiratory symptoms, airway inflammation, and airway hyperresponsiveness is related to prolonged exposure to chlorine by-products during their swimming careers.…”

Asthma, outdoor air quality and the Olympic Games

“…10 Various factors could contribute to the development of asthma in athletes, including environmental exposures, mechanical stress to the airways, increased prevalence of respiratory infections and dysautonomia. 10,15 The mechanisms by which these factors could influence asthma development may be related to their ability to induce airway inflammation and structural changes (remodelling). These processes are considered to be responsible for the development of airway hyperresponsiveness and variable or persistent airway obstruction.…”

“…These processes are considered to be responsible for the development of airway hyperresponsiveness and variable or persistent airway obstruction. [11][12][13][14][15][16][17] Airway inflammation and remodelling have been observed in athletes, even those without asthma. 18,19 In general, bronchial inflammation is of a mixed type, with increased neutrophil and eosinophil counts.…”

The Impact of Exercise-Induced Bronchoconstriction on Athletic Performance: A Systematic Review

“…This phenomenon, termed exerciseinduced bronchoconstriction (EIB), can occur either in the presence or absence of other characteristic features of asthma [5]. Indeed, EIB in elite athletes has a distinct pathogenesis and athletes frequently exceed normal resting lung function [6]. Moreover it is common to encounter athletes with a significant reduction in lung function post exercise who perceive few respiratory symptoms.…”