Comparative Effects of Breathing-Integrated Scapular Stabilization Versus Thoracic–Scapular Stabilization Exercises on Muscle Strength and Postural Alignment in Individuals with Shoulder Dysfunction: A Randomized Controlled Trial

Shoulder dysfunction characterized by scapular internal rotation is associated with muscle weakness, pectoralis minor shortening, and altered postural alignment. Although breathing-integrated scapular stabilization or thoracic–scapular stabilization exercises may improve these impairments, no prior study has directly compared their effects in this population. Methods: Thirty-two adults with shoulder dysfunction characterized by scapular internal rotation were randomly assigned to an experimental group (n = 16), which performed breathing-integrated scapular stabilization exercises, or a control group (n = 16), which performed thoracic–scapular stabilization exercises. Both groups participated in a 4-week intervention program conducted three times per week, with each session lasting 40 min. Muscle strength, pectoralis minor length (PML), and shoulder sagittal angle (SSA) were assessed at baseline and after the intervention. Data were analyzed using two-way repeated-measures ANOVA to examine group × time interactions, followed by Bonferroni-adjusted post hoc tests (α = 0.025). Results: No significant group × time interaction effects were observed for any outcome (p > 0.025), indicating that neither intervention demonstrated clear superiority over the other during the study period; however, both groups showed significant improvements over time in muscle strength, PML, and SSA following intervention (p < 0.025), except for upper trapezius strength, which did not change significantly. Conclusions: Both breathing-integrated scapular stabilization and thoracic–scapular stabilization exercises were associated with improvements in muscle strength, pectoralis minor length, and shoulder sagittal angle over time in individuals with shoulder dysfunction characterized by scapular internal rotation. However, no clear superiority of one intervention over the other was demonstrated during the 4-week study period.