Fifty-one children with bronchial asthma were recruited from King Khalid Hospital, Al-Kharj, Saudi Arabia. The study included children who had a confirmed diagnosis of bronchial asthma according to the Global Initiative for Asthma guidelines, aged 12-18 years, identified as being stable cases, had a baseline percent-predicted value of the peak expiratory flow rate of 60-80%, sustained stale doses of medications in the past three months. Children who had unstable asthma or exacerbated asthma symptoms, history of thoracic surgery, or cardiopulmonary comorbidities were excluded.
Outcome measures
1. Respiratory muscle strength: assessed by measuring the maximal inspiratory and expiratory pressure using an electronic respiratory pressure meter.
2. Pulmonary function: The forced vital capacity (FVC), forced expiratory volume in the first second of expiration (FEV1), and FEV1/FVC ratio, were measured in a pulmonary function test through a spirometry analyzer.
3. Control of asthma symptoms: Asthma symptoms were assessed using a translated version of the asthma control test.
All groups received the conventional respiratory re-training program, three times a week, for 12 weeks in succession. The placebo group additionally received unloaded respiratory muscle training, the inspiratory muscle training group received respiratory muscle training alone, and the combined group received combined inspiratory and expiratory muscle training in the same cycle. Interventions were conducted by a licensed physical therapist who had experience of more than 10 years of respiratory training.
