Pulmonology · Medical Literature
Is it time to focus on expiratory muscle training in children with asthma? A randomized controlled trial.
Abstract
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.
Clinical relevance
In clinically stable children with asthma aged 8–18 years, does an 8-week expiratory muscle training (EMT) program added to a home-based chest physiotherapy protocol improve pulmonary function, respiratory and peripheral muscle strength, peak cough flow, functional capacity, and asthma control compared with sham training plus the same physiotherapy program? __SNAPSHOT__ {"studyDesign":"Prospective, single-blinded randomized controlled trial","setting":"Not reported (authors affiliated with Turkish institutions based on author names; clinical setting not specified in the available abstract)","sampleSize":"n=30 (experimental group [EG]: not reported; sham group [SG]: not reported — allocation ratio not specified in the abstract)","population":"Clinically stable children with asthma, aged 8–18 years; severity spectrum, asthma medication regimen, baseline lung function values, and comorbidity exclusion criteria not reported in the abstract","intervention":"Expiratory muscle training (EMT) at 30% of maximal expiratory pressure (MEP) performed once daily for 8 weeks with weekly progressive load adjustments, added to a home-based chest physiotherapy program","comparator":"Sham group performing the identical home-based chest physiotherapy program with minimal (sub-therapeutic) resistance on the EMT device","primaryOutcome":"Not explicitly designated as a single primary endpoint in the available abstract; outcomes assessed include pulmonary function (FVC, FEV₁, PEF), respiratory muscle strength (MEP, MIP), peripheral muscle strength, peak cough flow (PCF), functional capacity, and Asthma Control Test (ACT) score","followUp":"8 weeks (assessments at baseline and at 8 weeks; no post-intervention follow-up reported)","fundingSource":"Not reported"}
Key findings
Based on the available abstract excerpt, FVC and FEV₁ improved significantly only in the experimental group (EG) receiving active EMT, whereas PEF increased in both groups — specific between-group effect sizes (mean differences), confidence intervals, and p-values for these comparisons are not reported in the available abstract and cannot be presented. Outcomes for maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), peripheral muscle strength, peak cough flow (PCF), functional capacity, and ACT score were assessed but their direction of change and statistical significance are not reported in the truncated abstract. No adverse event data or safety reporting is present in the available excerpt. NNT and NNH cannot be calculated from the information provided. All numerical effect estimates labelled herein as 'not reported' reflect the limitation of abstract-only availability.
Practice implications
This small single-blinded RCT (n=30) provides preliminary, hypothesis-generating evidence that 8 weeks of progressive EMT at 30% MEP may confer selective spirometric benefit (FVC, FEV₁) beyond sham training in clinically stable children with asthma. The between-group improvement in PEF in both arms suggests a non-specific effect of the shared physiotherapy program on expiratory flow, which is a clinically important contextual finding. However, the study does not establish whether EMT produces clinically meaningful improvements in patient-centered outcomes (symptom control, exacerbation rates, quality of life, or exercise tolerance), as full quantitative results, confidence intervals, and p-values are unavailable from the abstract alone. Generalizability is limited by the small sample, unspecified asthma severity distribution, single-blind design (assessor blinding status unclear), and the 8-week time horizon without follow-up. Children with severe or uncontrolled asthma, pre-school-aged children, and those with significant comorbidities were not adequately represented. Practice should not change on the basis of this study alone; confirmation in larger, adequately powered trials with longer follow-up and patient-important outcomes is required. Note: this summary is based solely on the available abstract excerpt; the full-text publication may contain additional findings, statistical detail, and safety data not captured here. __LIMITATIONS__ Very small sample size (n=30 total); likely underpowered for detection of clinically important between-group differences on all secondary outcomes,Single-blind design: participants could not be blinded to resistance level; outcome assessor blinding status not confirmed in the abstract,Abstract is truncated — primary vs. secondary outcome hierarchy, full statistical results (p-values, CIs, effect sizes), and adverse event data are not available for review,Short 8-week intervention with no post-training follow-up; durability of any spirometric gains is unknown,Home-based program introduces risk of adherence variability and non-standardized technique; monitoring methods not described,Sham resistance level not quantified; adequacy of sham blinding (perceived effort differences) cannot be assessed,Asthma severity spectrum, medication regimens, and baseline lung function percent-predicted values not reported — limits generalizability,Surrogate endpoints (FVC, FEV₁, MEP) used without mapping to patient-important outcomes such as exacerbation frequency, emergency visits, or validated quality-of-life instruments,Funding source not reported — potential for undisclosed conflicts of interest cannot be excluded,Statistical vs. clinical significance: even if between-group spirometric differences are statistically significant, minimal clinically important difference (MCID) thresholds for FVC and FEV₁ in this context are not addressed in the abstract __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This small (n=30), single-blinded, 8-week RCT suggests that expiratory muscle training added to chest physiotherapy may selectively improve FVC and FEV₁ in clinically stable children with asthma compared to sham training, while PEF improved in both groups. Full statistical results are unavailable from the truncated abstract, precluding confident assessment of effect size or clinical meaningfulness. EMT in pediatric asthma remains a promising but preliminary intervention requiring confirmation in larger, longer, fully reported trials before clinical integration.