Resistive Diaphragmatic Training Versus Volume-Oriented Spirometry on Pulmonary Function Test and Functional Capacity in Asthmatic Patients

Background: Asthma is a prevalent chronic respiratory condition marked by airway inflammation and bronchoconstriction, significantly impairing pulmonary function and exercise tolerance. Despite pharmacologic advancements, non-pharmacological interventions like respiratory muscle training remain underutilized in clinical practice. There exists a need to compare the clinical efficacy of targeted breathing strategies to guide evidence-based physiotherapeutic care. Objective: This study aimed to compare the effects of resistive diaphragmatic training (RDT) and volume-oriented spirometry (VOS) on pulmonary function, functional capacity, and asthma control among patients with moderate asthma. Methods: A single-blinded randomized controlled trial was conducted with 50 participants (n = 50), aged 35–50 years, diagnosed with moderate asthma (FEV₁% ≥ 60% and <80%). Subjects were randomly allocated into two groups receiving either RDT or VOS alongside baseline physiotherapy for six weeks. Pulmonary function tests (FVC, FEV₁, FEV₁/FVC), the 6-Minute Walk Test (6MWT), and the Asthma Control Test (ACT) were administered at baseline and post-intervention. Data were analyzed using SPSS v25, applying the Mann-Whitney U and Wilcoxon Signed Rank tests (p < 0.05). Ethical approval was obtained, and all procedures adhered to the Declaration of Helsinki. Results: The RDT group showed significantly greater improvements in FVC (3.37 ± 0.57 vs. 3.32 ± 0.28; p = 0.032), FEV₁ (2.61 ± 0.73 vs. 2.29 ± 0.24; p = 0.047), FEV₁/FVC ratio (73.84 ± 5.57 vs. 68.36 ± 5.45; p = 0.001), 6MWT (490.16 ± 52.58 m vs. 414.28 ± 26.96 m; p < 0.001), and ACT scores (19.96 ± 1.21 vs. 14.44 ± 1.66; p < 0.001), indicating both statistical and clinical significance. Conclusion: Resistive diaphragmatic training is more effective than volume-oriented spirometry in enhancing lung function, functional capacity, and asthma control in patients with moderate asthma. Its incorporation into routine asthma rehabilitation may yield improved clinical outcomes and reduce disease