[Is outdoor running exercise suitable for detecting bronchial hyperreactivity in children with mild episodic bronchial asthma?].

Bronchial hyperreactivity (BHR) can be proved by various methods. 21 children, 14 asthmatics and 7 healthy subjects were submitted to inhalative methacholine challenge as well as to 'free running' as a form of exercise challenge in a randomized sequence. For the methacholine inhalation a standardized procedure was followed and the provocative concentration defined (PC20) at which a decrease of more than 20% in FEV1 was found. There is no real standardisation for 'free running' (concerning temperature and humidity of the inspired air; individual level of exercise) but subjects had to run for 6 minutes while the heart rate should have been between 170 and 180 beats/minute. This increase in pulse rate relates to a submaximal work at which 60-85% of maximal O2 uptake are obtained. A decrease of 15% from basic value of FEV1 was defined as a positive result. By the use of methacholine inhalations we found 16 children (14 diseased, 2 controls) to be hyperreactive, whereas only 3 of them showed a positive result after 'free running'. We conclude, that firstly, methacholine provocations and exercise challenges assess different kinds of bronchial reactivity, secondly, 'free running' as a form of exercise is very difficult to standardize and therefore prone to errors and thirdly, 'free running' is not sensitive enough to assess BHR in children with mild asthma bronchiale if used as the only form of challenge. Problems concerning measurement of BHR are discussed.