All 40 patients with a diagnosis of asthma are recruited from the outpatients clinic of the department of Pediatric Pneumology and Allergology of the University Hospital Frankfurt. Patients undergo a methacholine challenge and two exercise challenges in a cold chamber and one exercise challenge in room temperature.

All subjects show bronchial hyperresponsiveness e.g. dyspnea when exercising in cold environment, in their medical history. Subjects undergo a methacholine challenge and exercise challenge in a cold chamber and one exercise challenge in room temperature.

Exercise challenge is defined as running on a treadmill for 6-8 minutes on submaximal work load in a cold chamber.

Lung function will be measured prior and after methacholine- and exercise/cold-air challenges. The maximal fall in forced expiratory volume in one second (FEV1, percent predicted) after methacholine and cold air challenge will be compared by statistical correlation. For both methods the sensitivity and the specificity to predict an exercise induced asthma will be calculated by a receiver operating characteristic (ROC analysis).

All subjects receive Salbutamol to relief them from bronchial constriction at the end of the test.

The combined exercise/cold-air challenge will be performed twice within one week. Post challenge the FEV1 will be measured after 5, 10, 20, and 30 minutes. The maximal fall in FEV1 (percent predicted) and the area under the curve (AUC) will be compared. The agreement and the repeatability of the maximal fall in FEV1 and of the AUC will be measured by correlation and by the method of Bland and Altman.

All children who participate will fill the asthma control test (ACT) and all adult subjects will fill the asthma control questionnaire (ACQ). The asthma-score will be compared with the severity of the exercise induced asthma measured by the maximal fall in FEV1.