Brief Summary:

This randomized controlled trial evaluated the short-term effects of inspiratory muscle training, aerobic exercise, combined inspiratory muscle training and aerobic exercise, placebo inspiratory muscle training, and usual care in women with stable chronic obstructive pulmonary disease (COPD). The study aimed to determine whether these interventions improve respiratory muscle strength, pulmonary function, walking capacity, dyspnea, and psychological well-being after a four-week intervention period. A secondary aim was to examine whether any improvements were maintained during a two-week detraining period after supervised training was stopped.

Participants were randomly assigned to one of five groups: control, inspiratory muscle training, aerobic exercise, combined inspiratory muscle training and aerobic exercise, or placebo inspiratory muscle training. Outcomes were assessed at baseline, after the four-week intervention, and on days 7 and 14 after the intervention. The main outcome was the change in maximal inspiratory pressure. Secondary outcomes included maximal expiratory pressure, peak inspiratory flow rate, inspiratory volume, forced vital capacity, forced expiratory volume in one second, six-minute walk distance, dyspnea, and well-being.

The study hypothesis was that inspiratory muscle training, either alone or combined with aerobic exercise, would improve respiratory muscle function, functional capacity, dyspnea, and well-being in women with COPD, and that the magnitude and persistence of these effects would differ between intervention groups.

Chronic obstructive pulmonary disease (COPD) is associated with airflow limitation, respiratory symptoms, reduced exercise tolerance, dyspnea, and impaired quality of life. In women with COPD, symptom burden and dyspnea may be more pronounced even at comparable levels of airflow limitation. Inspiratory muscle dysfunction may further contribute to breathing difficulty and reduced functional capacity. Therefore, interventions targeting inspiratory muscle performance may provide clinically relevant benefits in this population.

This single-center randomized controlled trial was designed to compare the effects of different short-term rehabilitation approaches in women with stable COPD. Participants were allocated to one of five parallel groups: usual care control, inspiratory muscle training, aerobic exercise, combined inspiratory muscle training plus aerobic exercise, or placebo inspiratory muscle training. The intervention period lasted four weeks, followed by a two-week detraining period during which supervised training was discontinued.

The inspiratory muscle training intervention used individualized resistance based on each participant's maximal inspiratory pressure, while the aerobic exercise intervention consisted of supervised treadmill walking at submaximal intensity. The combined group received both inspiratory muscle training and aerobic exercise. The placebo inspiratory muscle training group followed a similar breathing exercise procedure but with a low resistance load. The control group continued usual medical care without supervised exercise training.

The study was conducted at Hitit University Çorum Erol Olçok Training and Research Hospital. Assessments were performed before the intervention, immediately after the four-week intervention, and during follow-up on days 7 and 14 after the intervention. These follow-up measurements were included to examine whether the effects of training were maintained or reduced after the supervised intervention ended. The study focused on respiratory muscle performance, pulmonary function, walking capacity, perceived dyspnea, and psychological well-being in women with stable COPD

Inclusion Criteria:

Female patients aged between 48 and 65 years Diagnosis of stage I or II chronic obstructive pulmonary disease according to the Global Initiative for Chronic Obstructive Lung Disease criteria Stable COPD status No acute exacerbation within the previous six weeks Attending routine follow-up at the Chest Diseases Outpatient Clinic Non-use of tobacco products, including cigarettes, hookah, and other tobacco derivatives No medical condition that could interfere with safe exercise performance, such as serious cardiovascular, neurological, rheumatologic, orthopedic, or systemic disorders Ability to understand and communicate in Turkish No regular physical activity within the preceding three months, defined as moderate- to high-intensity exercise at least three days per week Voluntary participation with signed written informed consent

Exclusion Criteria:

Unstable COPD Acute COPD exacerbation within the previous six weeks Current tobacco use Medical contraindications to exercise, such as congestive heart failure, severe osteoarthritis, or advanced neurological disease Use of long-term home oxygen therapy Difficulty reading or comprehending Turkish Previous engagement in structured exercise either professionally or recreationally, including competitive athletes or individuals with formal exercise training Failure to attend at least three scheduled intervention sessions during the study period

Individual participant data will not be publicly shared due to participant confidentiality and ethical restrictions. Aggregate study findings may be shared in scientific publications.

Participants and intervention practitioners were blinded to the resistance level in the true inspiratory muscle training and placebo inspiratory muscle training groups. The device resistance was preset by the principal investigator before each session and concealed from the practitioners. Due to the nature of aerobic exercise, masking was not feasible for participants and supervising staff in the aerobic and combined exercise groups. Researchers responsible for data analysis remained blinded to group allocation until completion of the post-test assessments.