Exercise intolerance and exercise-induced bronchoconstriction in children.

Respiratory symptoms at rest or during exercise may restrain the physical capabilities required for normal motor and psychosocial development in children. The most frequent cause of exercise intolerance, apart from poor physical fitness, is exercise-induced bronchoconstriction (EIB), which may occur in some healthy children and in children with asthma. It is proposed that hyperventilation during exercise is associated with drying and cooling of airways, which can trigger a proinflammatory response. Several tests are used to confirm EIB, and the exercise-challenge test is the most common. Some nonpharmacologic therapies may induce airway refractoriness; warm-up exercise can result in the attenuation of EIB in more than half of the people with EIB. Prophylactic intermittent treatment with short-acting bronchodilators is the most commonly used treatment, but the conventional pharmacologic therapy for patients with uncontrolled asthma is the regular use of inhaled corticosteroids, with or without long-acting beta-agonists and montelukast. Therapy should result in optimal control of exercise-induced symptoms during habitual physical activity and also allow participation in sports activity in athletes.