MEDICAL SCIENCE

Hypothesis: exercise-induced asthma as a vascular phenomenon

Regular physical activity is strongly recommended to prevent chronic respiratory diseases, including asthma. On the other hand, vigorous physical training may trigger airway symptoms and bronchoconstriction. The transient airway narrowing occurring because of exercise is named exercise-induced bronchoconstriction (EIB). Despite management according to guidelines, a significant proportion of patients experiences uncontrolled EIB, which thus represents a relevant unmet medical need. In particular, although prevention and treatment of EIB are effectively based on the use of beta-2 bronchodilator drugs, high heterogeneity in individual responses has been reported. Furthermore, even though beta-2 adrenergic drugs remain the mainstay of EIB management, occurrence of tolerance and side effects, as well as doping concerns have been reported with their use. In regard to this, inhaled antimuscarinics could represent an alternative or additional effective and safe bronchodilator therapeutic option for achieving optimal EIB control and minimize adverse events.

The present systematic review aims to collect and provide the most updated and evidence-based literature findings on the efficacy and safety of short- and long-acting inhaled anti-muscarinic drugs for the preventive treatment of EIB in both children and adults.

Take-Home Message: Anti-muscarinic drugs are effective and safe in preventing EIB, despite response variability is reported. Further studies should focus on long-acting molecules, chronic administration and phenotype-driven effects.

Little is known about the behavior of operative lung volumes during exercise in patients with asthma and exercise-induced bronchoconstriction (EIB).

To compare the presence of dynamic hyperinflation (DH) in patients with mild asthma with and without EIB and in healthy individuals and to relate the changes in end-expiratory lung volume (EELV) with postexercise airflow reduction.

A total of 122 consecutive stable patients (>12 years of age) with mild asthma and 38 controls were studied. Baseline lung volumes were measured, and all patients performed an exercise bronchial challenge. At each minute of exercise, EELV and end-inspiratory lung volume (EILV) were estimated from inspiratory capacity measurements to align the tidal breathing flow-volume loops to within the maximal expiratory curve.

DH was more frequent in patients with asthma and EIB (76%) than in patients with asthma but without EIB (11%) or controls (18%). The EELV increased in patients with asthma and EIB and decreased in patients with asthma without EIB and controls during exercise. In the patients with asthma, the decrease in forced expiratory volume in 1 second after the exercise challenge correlated with age (r = −0.179, P = .05), baseline forced vital capacity (r = 0.255, P = .005), EELV increase (r = 0.447, P < .001), and EILV increase (r = 0.246, P = .007). Age, baseline forced vital capacity, and magnitude of DH were retained as independent predictors of EIB intensity.

In patients with asthma and EIB, the development of DH is very frequent and related to the intensity of postexercise bronchoconstriction. This finding could implicate DH in the development of EIB.

Le sport et les compétitions sportives occupent une place importante dans notre société où les athlètes de haut niveau sont souvent présentés comme des modèles. L’exercice physique est un facteur déclenchant classique de l’asthme et la pratique d’une activité physique régulière est importante pour maintenir une bonne qualité de vie au cours des maladies chroniques comme l’asthme et les allergies. Plusieurs enquêtes épidémiologiques ont montré que la prévalence de l’asthme et des allergies était anormalement élevée chez les individus pratiquant des sports en compétition par comparaison avec les sujets de la population générale. Le risque d’asthme varie en fonction du sport pratiqué. Les athlètes de haut niveau, en particulier les athlètes olympiques, pratiquant des sports d’endurance comme la natation, la course à pied ou les sports d’hiver ont un risque élevé d’asthme et d’allergies. Les sportifs de niveau moins élevé mais pratiquant une activité physique régulière sont soumis également à des risques. La rhinite allergique est environ deux fois plus fréquente chez les sportifs d’élite. L’auteur rappelle les mécanismes physiopathologiques de l’asthme et de la rhinite chez le sportif et leur prise en charge, en particulier chez le sportif de compétition. Chez le sportif de compétition, un certain nombre de médicaments habituellement utilisés par les asthmatiques et les patients atteints de rhinite allergique figurent sur la liste des produits interdits. Pour 2017, la World Anti-Doping Agency (WADA) a donné la liste de ces produits le 29 septembre 2016. Créées en 2007, les autorisations d’usages à des fins thérapeutiques (AUT) permettent aux sportifs de suivre un traitement à base de médicaments contenant une substance interdite. Certains, y compris des sportifs, les considèrent comme une forme déguisée de dopage.

Sport and sporting competitions play an important role in our society, with high-level athletes frequently being held up as role models. Physical exercise is a classic triggering factor for asthma and regular physical activity is essential to maintain a good quality of life during the course of chronic diseases such as asthma and allergies. Several epidemiological surveys have revealed an abnormally high prevalence of asthma and allergies in individuals involved in competitive sports compared with the general population. The risk of asthma varies in accordance with the type of sport practised. High-level athletes, particularly Olympic athletes, practising endurance sports such as swimming, running and winter sports, are at high risk for asthma and allergies. However, sportsmen regularly practising physical activities at a less intense level are also subject to risk. Allergic rhinitis occurs around twice as frequently in elite sportsmen. The author reviews the physiopathological mechanisms of asthma and rhinitis in athletes and the treatment thereof, particularly in competitive athletes. In this population, a certain number of medicines ordinarily used by normal subjects with asthma and allergic rhinitis are in fact on the list of banned substances. On 29 September 2016, the World Anti-Doping Agency (WADA) issued a list of these substances for 2017. Since their creation in 2007, therapeutic use exemptions (TUE) have enabled athletes to follow treatments containing such banned substances. However, certain observers, including some athletes, consider this practice to be a form of disguised doping.

The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population.

Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges.

This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.