Background:

Inspiratory muscle training combined with positive expiratory pressure (IMT/PEP) may improve outcomes in chronic obstructive pulmonary disease (COPD), but evidence in exacerbation-prone (Group E) disease is limited. This study is designed to evaluate the effects of IMT/PEP on pulmonary function, respiratory muscle strength, exercise capacity, and dyspnea in stable Group E COPD.

Methods :

This prospective randomized controlled trial will enroll 62 patients with stable Group E COPD between June 2023 and September 2024. Participants will be randomized to receive IMT/PEP plus standard care or standard care alone. Pulmonary function tests, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), six-minute walk test (6MWT), oxygen saturation (SO₂), and dyspnea scales (mMRC, CAT, MBS, VAS) will be assessed at baseline, 1 month, and 3 months.

Inclusion Criteria:

Age ≥ 40 years

Diagnosis of Group E COPD according to GOLD 2023 criteria

Post-bronchodilator FEV₁/FVC < 0.70 and FEV₁ < 50% predicted

mMRC score ≥ 2 or CAT score ≥ 10

History of ≥2 exacerbations or ≥1 hospitalization in the past year

Stable clinical condition (no exacerbation in the past 2 weeks)

Ability and willingness to perform IMT/PEP therapy

Provided written informed consent

Exclusion Criteria:

Acute exacerbation of COPD at time of enrollment

Contraindications to pulmonary function testing or 6-minute walk test (e.g., recent myocardial infarction, unstable angina)

Inability to perform inspiratory or expiratory maneuvers reliably (e.g., due to cognitive or neuromuscular disorders)

Significant orofacial muscle weakness unresponsive to modified mouthpiece

Participation in another interventional study within the past 3 months

Nonadherence to COPD treatment plan

Any condition deemed by investigators to interfere with study participation

Adults aged 40 years and older diagnosed with Group E chronic obstructive pulmonary disease (COPD) according to GOLD 2024 criteria, with moderate to very severe airflow limitation, increased symptom burden, and a history of frequent exacerbations or hospitalizations.

The decision to share individual participant data (IPD) has not been finalized. Data sharing may be considered upon reasonable request, pending ethical approval and institutional data protection policies.