Inclusion Criteria:  Confirmed diagnosis of asthma according to Global Initiative of Asthma guidelines. Age between 12 and 18 years. Clinically stable asthma. Stable doses of medications in the last three months A percent-predicted value of the peak expiratory flow rate of 60-80% No activity limitation due to asthma  Exclusion Criteria:  Unstable asthma Exacerbation of asthma symptoms History of thoracic surgery Cognitive/behavioral problems Cardiopulmonary co-morbidities