FACTORS AFFECTING EXERCISE INDUCED BRONCHOSPASM

哮喘是导致儿童功能障碍的第二大原因 45岁年龄组。体力活动引起的症状急性加重 这些患者易感的劳累可能会进一步加剧。 受寒冷和/或干燥环境的影响。令人信服的证据表明 支气管收缩的机制是通过呼吸道散热， 继而导致呼吸道的冷却。然而，在锻炼过程中， 哮喘患者和正常人都表现出呼气增加。 最有可能是由于支气管扩张和弹性增加造成的血流 肺的后仰。因此，看起来这一机制 造成这种气流增加的原因是一种竞争机制 运动性支气管痉挛(EIB)。游泳训练总体上减少 哮喘残疾评分和药物使用，但不会降低EIB 严肃性。跑步训练似乎实现了这些好处，也 降低EIB。我们假设这两种形式之间的差异 训练是适应性呼吸刺激的不同之处。运行结果 在呼吸道冷却阈值的增加，由于适应过程 大范围反复高呼吸所致的呼吸道 气候条件的影响。温暖潮湿的游泳池环境会 而不是提供有效的适应性刺激。这个项目的目的是 评估身体健康和/或呼吸道适应在EIB中的作用 通过游泳和跑步训练降温，加上三种方式的常压呼吸过多 跨界设计。

Asthma is the second leading cause of functional limitation in the under 45-year-old age group. The acute exacerbation of symptomes by physical exertion to which these patients are susceptible can be further exacerbated by a cold and/or dry environment. There is compelling evidence that the mechanism for bronchoconstriction is loss of heat from the airways with consequent cooling of the respiratory tract. During exercise, however, both asthnatics and normal subjects demonstrate an increased expiratory flow which is most likely due to both bronchodilation and increased elastic recoil of the lung. It would appear, therefore, that the mechanism responsible for this increase in airflow serves as a competetive mechanism to exercise-induced bronchospasm (EIB). Swim training decreases overall asthma disability scores and use of medicine but does not diminish EIB severity. Run training appears to accomplish these benefits and also to reduce EIB. We hypothesize that the difference between these two forms of training is a difference in adaptive respiration stimulus. Running results in an increase in threshold to airway cooling due to an adaptive process in the respiratory tract from repeated bouts of hyperpnea under a broad range of climatic conditions. The warm, humid swimming pool environment would not provide a sifficiently adaptive stimulus. The aim of this project is to asses the roles in EIB of physical fitness and/or airway adaptation to cooling via swim and run training plus eucapnic hyperpnea in a three-way crossover design.