The effect of endurance training on exercise-induced bronchospasm.

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Asthmatic children often experience limitations of their physical activity due to exercise induced bronchospasms (EIB). It is therefore necessary to control their EIB in order to help them in their physical and social maturation. In this study we attempt to clarify the risk factors and the exercise conditions which relate to the severity of EIB, based on the physiological responses measured during various intensities of aerobic exercise and thus determined the optimal intensity of exercise therapy in asthmatic children. Finally, the influence of endurance training on the EIB was also investigated.In the first year of a three-year study, the effects of exercise intensity on EIB was evaluated in order to determine the optimal exercise intensity for exercise therapy. Based on our findings, the severity of EIB was found to depend on the exercise intensity. It was also determined that a 125% intensity of the lactate threshold (125% LT) is the upper limit of exercise intensity which allows a … More sthmatic children to improve their aerobic working capacity and perform without suffering any severe bronchospasms. In the second year of this study, endurance training was performed on a cycle ergometer for 30min, 6times a week for 4weeks at 125% LT.As a result, endurance training improved their aerobic capacity and also reduced the severity of EIB at an absolute work load. It was thus suggested that the reduction in the severity of EIB was attributable to the increase in the aerobic capacity. We then prolonged the training term for 2 months. After 2 months of endurance training, the severity of EIB was found to have reduced not only the absolute but also the relative work load. This reduction in the severity of EIB at a relative work load indicates that some changes in the clinical factors which cause EIB might occur due to exercise training. In the third year of this study, the influence of detraining for 3 weeks on the effect of endurance training for 6 weeks, EIB, bronchial hyperreactivity and aerobic working capacity was examined. Based on our findings, the loss of adaptation for EIB and bronchial hyperreactivity may be slower than that of the aerobic working capacity following detraining. Endurance training thus appears to alter some of the clinical factors which cause EIB.It was therefore concluded that endurance training not only improved the aerobic working capacity but also reduced the severity of EIB and bronchial hyperreactivity, and is thus considered to be an effective therapy for improving clinical manifestations. Less