Respiratory Muscle Performance and Pulmonary Function in Sarcopenic and Non-Sarcopenic Patients with Multiple Sclerosis: A Cross-Sectional Study

Background: Respiratory muscle dysfunction is a recognized complication of multiple sclerosis (MS) and may contribute to functional decline. Sarcopenia related to neurological impairment may further impair respiratory muscle performance in MS. This study aimed to investigate the association between sarcopenia and respiratory function, respiratory muscle strength, and respiratory muscle endurance in patients with MS. Methods: This study was designed as a cross-sectional observational study. In this study, 52 MS patients (26 sarcopenic, 26 non-sarcopenic) were evaluated. Sarcopenia was assessed using the SARC-F questionnaire, handgrip strength, bioelectrical impedance analysis, calf circumference, and walking speed (6-m walk test). Pulmonary function was evaluated using spirometry. Respiratory muscle strength was assessed using maximal inspiratory and expiratory pressures (MIP, MEP), and respiratory muscle endurance was evaluated using a constant-load test. Results: Respiratory muscle endurance (p < 0.001), inspiratory volume (p < 0.001), and forced vital capacity (p = 0.003) were significantly lower in sarcopenic MS patients in the primary analyses. However, inspiratory volume and respiratory muscle endurance remained significant after age adjustment, while all three parameters remained significant after EDSS adjustment. No significant differences were observed between groups in other respiratory function parameters or respiratory muscle strength including MIP, and MEP (p > 0.05). Conclusions: Sarcopenia is associated with reduced respiratory muscle endurance and respiratory capacity in patients with MS. These findings suggest that respiratory muscle endurance assessment may help identify sarcopenic MS patients who warrant further respiratory evaluation. Incorporating respiratory muscle endurance assessment into routine evaluation and rehabilitation strategies may be beneficial in sarcopenic MS patients.