Impact of Inspiratory Muscle Training with Biofeedback vs Traditional Breathing Exercises on Dyspnea and Exercise Tolerance in COPD: A Randomized Controlled Trial

Background: Chronic obstructive pulmonary disease (COPD) is one of the leading causes of disability globally, with symptoms that include dyspnea and exercise intolerance. Although breathing exercises are typically considered standard of care in rehabilitation, inspiratory muscle training (IMT) with visual biofeedback might be more beneficial. In this study we visualized the effects of IMT with visual biofeedback compared to breathing exercises on dyspnea and exercise tolerance in patients with COPD. Methods: A parallel-group, assessor-blinded randomized controlled trial was conducted across three sites between March and November 2024. Sixty-six adults, ages 40-60, with moderate to severe COPD (GOLD stages II-III) were randomized to an IMT group using an incentive spirometer with visual biofeedback (n=33) or a breathing exercise group (n=33). All participants engaged in 6 weeks of intervention. The primary outcomes were dyspnea (mMRC scale, Borg CR10) and exercise tolerance (6-minute walk distance, 6MWD). Secondary outcomes included pulmonary function (FEV1% predicted) and health-related quality of life (CAT score). Data were analyzed using independent t-tests and repeated measures ANOVA. Results: Significant within-group improvements were observed in both groups; however, the IMT-biofeedback group exhibited a greater magnitude of between-group differences measured by mMRC (-0.4 points, p=0.002), Borg CR10 (-0.8 points, p=0.001), 6MWD (+34.7 meters, p<0.001), FEV1 % predicted (+3.7%, p=0.001), and CAT score (-2.5 points, p=0.001). Effect sizes ranged from 0.84 to 1.09, and all outcomes demonstrated statistically significant time × group interactions (p≤0.001). No adverse events were registered during the study in either group. Conclusion: For patients with moderate-to-severe COPD, inspiratory muscle training with visual biofeedback in addition to breathing exercises is significantly more effective in improving dyspnea, exercise tolerance, pulmonary function, and quality of life compared to traditional breathing exercises alone, which supports its added value in the pulmonary rehabilitation curriculum. DOI: https://doi.org/10.59564/amrj/03.04/004