Asthma is the most common chronic lung disease in children. It affects more than 1 in 10 children in France. The methacholine bronchial challenge test (MBT) is indicated to assess the probability of asthma suggested by clinical symptoms by measuring the forced expiratory volume in one second (FEV1), after inhalation of a cumulative dose of methacholine. In children, the measurement of FEV1 requires a high level of cooperation from the child, which can be the source of false negatives or no result if this is not obtained. The objective of this study is to evaluate if the measurement of the respiratory function by the forced oscillations technique, allows to predict the variation of the FEV1 obtained

Inclusion Criteria:

• Age between 6 and 16 years
• FEV1 > 60%
• Child referred to the pulmonary function test laboratory for a non-specific bronchial hyperactivity test with methacholine
• Child under treatment with inhaled corticosteroids stopped for at least 3 weeks
• Oral consent from the child and at least one of the legal representatives
• Child affiliated or benefiting from a social security plan

Exclusion Criteria:

• Use of a short-acting beta-adrenergic bronchodilator within the last 6 hours or anticholinergic bronchodilator within the last 12 hours
• Use of a long-acting beta-adrenergic bronchodilator (licensed for use in children) in the past 36 hours
• Upper or lower respiratory tract infections within 3 weeks prior to inclusion
• Epilepsy under treatment
• Subject's participation in another interventional study that may alter respiratory function
• Patient unable to give consent, vulnerable