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.

Static hyperinflation is associated with decreased peak exercise performance in children with cystic fibrosis.

BACKGROUND: We evaluated the exercise capacity of children with cystic fibrosis to determine whether ventilatory limitation associated with static hyperinflation is related with decreased exercise capacity, thus predisposing these children to arterial hypoxemia during progressive exercise. METHODS: Thirty-seven children, ages 8-17 years, underwent spirometry, body plethysmography, and cardiopulmonary exercise testing after arterial catheter placement. According to the ratio of residual volume to total lung capacity (RV/TLC), the subjects were categorized as either with (RV/TLC > 30%) or without static hyperinflation (RV/TLC < 30%). RESULTS: Children with static hyperinflation showed lower values of maximum load per kilogram (% predicted) (P = .01), which was aggravated by ventilatory limitation (FEV(1) < 80% of predicted, peak oxygen consumption [% predicted] < 85%, and breathing reserve index > 0.7). Subjects with ventilatory limitation had significantly lower oxygen saturation (P = .04) and hypoxemia (P = .03) than did subjects without ventilatory limitation. CONCLUSIONS: In children with cystic fibrosis, static hyperinflation and ventilatory limitation are associated with decrease in exercise performance, oxygen saturation, and P(aO(2)) during maximum cardiopulmonary exercise testing. All children with cystic fibrosis who exhibit static hyperinflation and ventilatory limitation may require S(aO(2)) monitoring during progressive exercise.