[Asthma and exercise].

Exercise-induced asthma (EIA) is defined as the clinical occurrence of shortness of breath, cough or wheeze that occurs typically 5-15 minutes after the cessation of the exercise. In most patients with EIA, bronchoconstriction is followed by a refractory period, during which repeated exertion causes less bronchoconstriction. The occurrence of this type of asthma is influenced by the intensity and the duration of exercise. It is now generally believed that EIA affects all patients with asthma if challenged with exercise of sufficient intensity. The estimate prevalence varies from 7 to 15% in the general population. EIA appears also to affect 3-14% of athletes. It is now clear that hyperventilation and hypertonicity of airway-lining fluid provide the stimulus for EIA with release of constrictor mediators. Recently, incidence of new diagnoses of asthma is associated with heavy exercise in communities with high concentrations of ozone, thus, air pollution and outdoor exercise could contribute to the development of asthma in children. Beta-agonists and/or disodium cromoglycate remain the preferred first-line therapy for EIA but now antileukotrienes provide an attractive therapeutic alternative. General recommendations can help reduce its severity: warm-up; breath through mask when exercising in cold, dry conditions; in recent years some reports have suggested that training and conditioning may help athletes and non-athletes with asthma have fewer symptoms after exercise, increase the threshold of exercise necessary to induce airway obstruction and finally improve their well-being. Scuba diving stays an absolute contra-indication if asthma.