Is it time to focus on expiratory muscle training in children with asthma? A randomized controlled trial

Respiratory muscle dysfunction contributes to reduced pulmonary and extrapulmonary outcomes in children with asthma. Although inspiratory muscle training has been widely studied, the effects of expiratory muscle training (EMT) in pediatric asthma remain unclear. This study investigated the effects of EMT on pulmonary function, respiratory and peripheral muscle strength, peak cough flow (PCF), functional capacity, and asthma control in children with asthma. This prospective, single-blinded randomized controlled trial included 30 clinically stable children with asthma aged 8-18 years. Participants were randomly assigned to an experimental group (EG) receiving EMT in addition to a home-based chest physiotherapy program or a sham group (SG) performing the same program with minimal resistance. EMT was performed once daily for 8 weeks at 30% of maximal expiratory pressure (MEP) with weekly load adjustments. Pulmonary function, respiratory and peripheral muscle strength, PCF, functional capacity, and asthma control test (ACT) scores were assessed at baseline and after 8 weeks. FVC and FEV₁ improved significantly only in the EG, whereas PEF increased in both groups with greater improvement in the EG. MIP increased in both groups, while MEP and MEP (% predicted) improved only in the EG. PCF, quadriceps strength, and 6MWT distance improved in both groups, with greater gains in the EG. ACT scores increased significantly in both groups but improved more in the EG.

Adding 8 weeks of EMT to chest physiotherapy improved pulmonary function, respiratory and peripheral muscle strength, cough effectiveness, functional capacity, and asthma control in children with asthma. EMT appears to be a safe and effective adjunct to pediatric asthma management.

The study was prospectively registered on the ClinicalTrials.gov website (registration number: NCT07169071; Date: 09/05/2025).

• Respiratory muscle dysfunction is common in children with asthma and may contribute to reduced pulmonary function, ineffective cough, and decreased exercise capacity. • Most respiratory muscle training studies in asthma have focused primarily on inspiratory muscle training, while the role of expiratory muscle training remains largely unexplored.

• This randomized controlled trial investigates the effects of expiratory muscle training (EMT) in children with asthma when combined with a home-based chest physiotherapy program. • The addition of 8 weeks of EMT resulted in greater improvements in pulmonary function, respiratory muscle strength, cough effectiveness, functional capacity, and asthma control compared with sham training.