This study investigates the effect of threshold inspiratory muscle training on diaphragm thickness and diaphragm excursion, measured using ultrasonography, in patients with stable chronic obstructive pulmonary disease (COPD).

This quasi-experimental study with a pretest-posttest design evaluates the effect of a 6-week structured threshold inspiratory muscle training program on diaphragm thickness and diaphragm excursion in patients with stable COPD. Conducted at the medical rehabilitation polyclinic of Rotinsulu Hospital, Bandung, this study includes patients who meet specific inclusion criteria. The intervention is performed once daily, five times per week, with progressive intensity based on maximal inspiratory pressure using a threshold device. Outcomes will be assessed using ultrasonography to measure diaphragm thickness and diaphragm excursion before and after the intervention.

Inclusion Criteria:

• Patients with a COPD GOLD stage 2
• Age 40-59 years
• Maximal Inspiratory Pressure (MIP) value of less than 70 cmH₂O or below the lower limit of normal for their age and gender
• Clinically stable for at least 4 weeks prior to the study
• Ready to participate in research and sign informed consent

Exclusion Criteria:

• Patients with contraindications to Inspiratory Muscle Training or spirometry (e.g., recent thoracic or abdominal surgery, pneumothorax, or history of spontaneous pneumothorax).
• Patients participating in other structured respiratory muscle training or pulmonary rehabilitation programs concurrently that could confound the results
• Patients undergoing other therapies that may affect diaphragmatic muscle measurement results, such as electrical diaphragmatic stimulation