COMPARATIVE EFFECT OF DIAPHRAGMATIC BREATHING AND PURSED-LIP BREATHING, EACH DELIVERED ALONGSIDE INSPIRATORY MUSCLE TRAINING, ON PULMONARY FUNCTION, DYSPNEA, AND FUNCTIONAL CAPACITY IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE: A RANDOMIZED COMPARATIVE S

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is a progressive condition marked by ongoing airflow restriction, breathlessness, and declining functional capacity. Clinicians often pair inspiratory muscle training (IMT) with breathing-retraining approaches such as diaphragmatic breathing (DB) and pursed-lip breathing (PLB) to strengthen pulmonary rehabilitation outcomes, yet head-to-head evidence comparing these two pairings is sparse. Objective: To compare DB paired with IMT against PLB paired with IMT with respect to pulmonary function, dyspnea, blood oxygen levels, and walking capacity in people living with moderate COPD. Methods: This randomized, comparative, pre-post trial enrolled 60 patients with GOLD stage 2 COPD (ages 18–80) from a tertiary care hospital, split evenly by a chit-based random draw into two arms. Group A (n=30) practiced DB together with breather-device IMT, and Group B (n=30) practiced PLB together with the same device-based IMT, each for 15–20 minutes twice a day across two weeks. The six-minute walk distance (6MWD), Modified Borg Dyspnea Scale, peak expiratory flow rate (PEFR), and arterial oxygen saturation (SpO₂) were captured before and after the intervention period. Pre-post shifts within each arm were tested with the Wilcoxon signed-rank test, arm-to-arm differences with the Mann Whitney U test, and baseline-controlled comparisons with analysis of covariance (ANCOVA). Results: Both arms improved significantly from baseline across every measure (p<0.001). Group B's gains exceeded Group A's for PEFR (mean change 205.00±45.69 vs. 87.33±29.00 L/min), SpO₂ (7.93±2.83% vs. 3.00±1.49%), Modified Borg score (−1.80±0.78 vs. −0.93±0.58), and 6MWD (156.17±38.50 m vs. 85.83±21.50 m), with all between-arm comparisons reaching p<0.001. After controlling for baseline value, age, and gender, ANCOVA confirmed a statistically significant advantage for Group B on all four measures (all p<0.001). Conclusion: Both breathing strategies paired with IMT delivered clinically worthwhile short-term gains for people with COPD, but the PLB-plus-IMT combination outperformed DB-plus-IMT by a clear margin. Device-assisted PLB may therefore be a practical, inexpensive addition to pulmonary rehabilitation programs for patients with moderate COPD.