Effects of Expiratory Muscle Training Added to Pulmonary Rehabilitation in Patients With Bronchiectasis

his study will be conducted as a randomized controlled, single-blind, parallel-group trial. Ethical approval has been applied for from the University of Health Sciences Hamidiye Non-Drug and Non-Medical Device Interventional Research Ethics Committee, and the evaluation process is currently ongoing. Upon receipt of the ethical approval, the approval document will be submitted to the Scientific Research Projects (BAP) Commission by the principal investigator.

Following ethical approval, individuals aged 18-70 years with a clinical diagnosis of stable non-cystic fibrosis bronchiectasis who are being followed at the Pulmonary Rehabilitation Unit of the University of Health Sciences Süreyyapaşa Chest Diseases and Thoracic Surgery Training and Research Hospital will be eligible for inclusion. Patients who have experienced an acute exacerbation within the last three months, have severe cardiac, neurological, or orthopedic diseases, demonstrate lack of cooperation, or have communication difficulties will be excluded from the study.

Eligible participants will be randomly assigned to one of two groups using a simple randomization method: (1) a control group receiving a standard pulmonary rehabilitation program, and (2) an intervention group receiving standard pulmonary rehabilitation combined with expiratory muscle training.

The standard pulmonary rehabilitation program will be conducted on an outpatient basis for eight weeks, three days per week, under direct supervision. Prior to enrollment, all participants will undergo cardiology consultation, lower extremity venous Doppler ultrasonography for deep vein thrombosis screening, chest radiography, electrocardiography, pulmonary function testing, and routine laboratory assessments. Baseline evaluations will include symptom assessment, physical examination, oxygen saturation levels, current medical treatments, comorbidities, disease duration, oxygen therapy requirements, use of respiratory support devices, smoking history, and anthropometric measurements (height, weight, body mass index, and fat-free mass). Pulmonary function tests (FVC, FEV₁, and diffusion capacity), nutritional assessment, medication review and education, disease-related patient and caregiver education, and functional exercise capacity assessment using field tests such as the 6-minute walk test will be performed. All assessments will be repeated at the end of the rehabilitation program. Written informed consent will be obtained from all participants prior to inclusion.

During the eight-week rehabilitation period, participants will attend supervised sessions at the hospital three days per week and will be encouraged to continue prescribed exercises at home on non-supervised days using an exercise diary. Oxygen saturation and heart rate will be continuously monitored using pulse oximetry during sessions, and blood pressure measurements will be taken before and after exercise. Perceived dyspnea and fatigue levels will be assessed using the Borg scale.

Exercise training will be individualized based on baseline exercise capacity assessments. Each session will include upper and lower extremity strengthening exercises, stretching, relaxation exercises, aerobic training (treadmill walking and cycling), breathing exercises, and relaxation techniques. Aerobic exercise will be performed at 60-80% of the target heart rate, consisting of a 10-minute warm-up, 30 minutes of aerobic exercise, and a 10-minute cool-down period. Resistance training will be performed at 50% of one-repetition maximum, with one set of 10 repetitions per session, targeting both upper and lower extremity muscle groups.

In addition to pulmonary rehabilitation, participants in the intervention group will perform expiratory muscle training using an adjustable PowerBreathe EX1 expiratory muscle training device. The initial training resistance will be set at 30-40% of maximal expiratory pressure (MEP) and will be progressively increased by 5-10% on a weekly basis. Training will be performed three days per week, consisting of two sets per day, with each set including 10-15 repetitions.

Outcome measures will be assessed at baseline and after completion of the intervention period by an experienced physiotherapist using standardized procedures in accordance with international guidelines. Pulmonary function will be assessed using spirometry to measure forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and the FEV₁/FVC ratio, following American Thoracic Society (ATS) and European Respiratory Society (ERS) standards. Peak cough flow will be measured in liters per minute using a peak flow meter. Respiratory muscle strength will be evaluated by measuring maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) using a digital manometer in accordance with ATS/ERS guidelines. Functional exercise capacity will be assessed using the 6-minute walk test performed on a 30-meter corridor according to ATS protocol, with continuous monitoring of oxygen saturation, heart rate, and perceived exertion using the Borg scale. Dyspnea severity will be evaluated using the modified Medical Research Council (mMRC) dyspnea scale. Health-related quality of life will be assessed using the St. George's Respiratory Questionnaire (SGRQ). Fatigue severity will be evaluated using the Fatigue Severity Scale.

Statistical analysis will be performed using SPSS software. Normally distributed data will be analyzed using independent and paired t-tests, while non-normally distributed data will be analyzed using the Mann-Whitney U test and Wilcoxon signed-rank test. Statistical significance will be set at p \< 0.05. Sample size was determined using power analysis with G\*Power version 3.1.9.7. Based on an effect size of 0.25, a significance level of 0.05, and a power of 0.80, a total sample size of 34 participants was calculated. Considering a potential dropout rate of 15%, the total sample size was increased to 40 participants.

• Dyspnea Severity [Time frame: Baseline and 8 weeks]
• Health-Related Quality of Life [Time frame: Baseline and 8 weeks]
• Fatigue Severity [Time frame: Baseline and 8 weeks]