Impact of respiratory muscle training on muscle strength, pulmonary function, symptoms, and quality of life in COPD.

Abstract

Introduction: Chronic obstructive pulmonary disease (COPD) is characterized by respiratory muscle weakness, hyperinflation, and systemic inflammation, leading to impaired pulmonary function and quality of life. Respiratory muscle training (RMT) may strengthen the inspiratory and expiratory muscles, improve pulmonary function, reduce dyspnea, and enhance functional outcomes. This study assessed the impact of concurrent RMT on respiratory muscle strength, spirometry, dyspnea, and quality of life in patients with COPD.

Materials and methods: This was a single-cohort pre/post-intervention study initially recruiting 43 patients with COPD to participate in an 8-week RMT program using a threshold pressure device. Both inspiratory and expiratory training were performed using a PowerLung device with adjustable resistance. Training consisted of three sets of ten breaths twice daily for each mode, and participants were instructed to increase resistance incrementally when the load became easy. Assessments included spirometry, maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), COPD Assessment Test (CAT), Medical Research Council (MRC) Breathlessness Scale, and Airways Questionnaire 20 (AQ20). Data were collected at baseline and post-intervention and analyzed using paired t-tests and Wilcoxon signed-rank tests, stratified by GOLD category.

Results: Twenty-seven participants completed the study. Statistically significant improvements were observed in MIP (mean increase 14.1 cm H₂O, p < .001), MEP (mean increase 20.1 cm H₂O, p < .001), CAT (mean decrease 2.92, p = .020), and AQ20 (mean decrease 1.67, p = .005). FEV₁ improved modestly but did not reach statistical significance (mean increase 0.0367 L, p = .064). The GOLD distribution included eight participants in GOLD 2, 12 in GOLD 3, and seven in GOLD 4. Improvements in MIP and MEP were statistically significant within all GOLD categories. A clinically meaningful increase in FEV₁ (≥ 60 mL) was observed in participants in GOLD 3 and 4 stages, though not statistically significant. Correlations between muscle strength improvements and symptom scores were moderate to strong.

Discussion: Concurrent RMT improves respiratory muscle strength and quality of life in patients with COPD, with the greatest benefits observed in advanced disease stages. Enhanced respiratory muscle efficiency may reduce dyspnea and promote exercise tolerance.

Conclusion: RMT is a promising intervention for COPD management that offers improved respiratory muscle strength and quality of life. Future studies should explore the long-term effects and optimize protocols for broader implementation.