Associations Between Musculoskeletal Structural Parameters and Pulmonary Function in Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

Background/Objectives: This study aimed to compare structural and functional parameters between chronic obstructive pulmonary disease (COPD) patients and healthy controls, assess associations with pulmonary function, and identify factors independently associated with COPD status. Methods: A cross-sectional study was conducted in 89 participants (COPD: n = 45; controls: n = 44). Structural parameters included forward shoulder posture (FSP), scapular rotation, scapular distance (SD), and pectoralis minor index, measured bilaterally. Functional parameters included maximum inspiratory and expiratory pressures (MIP/MEP), chest expansion at three thoracic levels, spinal angles, and spirometry (%FVC, %FEV1, FEV1/FVC, FEF25–75%, PEFR). Univariate and stepwise multivariate logistic regression identified variables independently associated with COPD. Results: COPD patients were older and exhibited lower anthropometric measures. Scapular rotation was greater in COPD (p < 0.05 bilaterally), while SD was significantly reduced (p < 0.001 bilaterally). MIP, MEP, and chest expansion at all three levels were significantly impaired in COPD (p < 0.05). All spirometric parameters were markedly lower in COPD (all p < 0.001). SD was positively associated with spirometric indices on both sides (p < 0.01). FSP was inversely associated with MIP, MEP, and chest expansion (p < 0.05). In multivariate logistic regression, age (OR 1.280, p = 0.018), %FVC (OR 0.875, p = 0.029), and FEF25–75% (OR 0.909, p < 0.001) were independently associated with COPD status. Conclusions: Patients with COPD demonstrated reduced SD and increased scapular rotation. SD was significantly associated with pulmonary function, whereas FEF25–75% and %FVC emerged as independently associated variables of COPD status. Collectively, these findings underscore the clinical relevance of integrating targeted scapulothoracic and respiratory rehabilitation strategies to optimize functional outcomes and support overall respiratory health and well-being.