Study of exercise induced bronchospasm by various loading tests.

In 378 children affected by asthma and 87 healthy children, physical loading was carried out by three kinds of test, viz. free running, stairstep test or skipping, and bicycle ergometry. In 32% of healthy children physical exercise led to improved respiratory function, while this value was only 7% in asthmatics. An improvement in respiratory function exceeding 20%, i.e. appreciable bronchial dilatation, never occurred in asthma patients. The bronchospasm of healthy children showed no consistent time course, in asthmatics it was most pronounced three minutes after exercise. Exercise induced bronchospasm occurred most frequently after free running, least frequently after ergometric loading. The stairstep test and skipping provoked exercise induced bronchospasm in a nearly identical proportion. Severity of exercise induced bronchospasm exhibited a similar distribution. In addition to cases with a positive response to running test, some of the other methods revealed further 5-6% of cases. Free running is the most suitable method for demonstration of exercise induced bronchospasm, ergometric loading appears the least sensitive test in this respect. By application of three loading tests exercise induced bronchospasm could be demonstrated in 52% of paediatric asthma patients.