The relationship between respiratory functions, exercise capacity and peripheral muscle strength in hemodialysis patients: a cross-sectional study

Abstract

Introduction: Patients undergoing hemodialysis may experience a wide range of symptoms and functional limitations that can negatively affect their physical abilities and daily activities. Objective: To investigate the relationships between pulmonary function, inspiratory muscle parameters, exercise capacity, and peripheral muscle strength in hemodialysis patients. Methods: Thirty hemodialysis patients participated in this cross-sectional study. Respiratory function was evaluated using spirometry, and dynamic inspiratory muscle performance was assessed with the POWERbreatheK5 device to measure Strength Index (S-index), peak inspiratory flow (PIF), and inspiratory volume. Exercise capacity was evaluated using a six-minute walk test (6MWT), and lower extremity functional performance was assessed using a 30-second sit-to-stand test (30s-STS). Peripheral muscle strength was determined by measuring the strength of the biceps brachii in the dominant upper extremity and the quadriceps in both lower extremities. Results: The mean age of the patients was 53.53 ± 11.53 years. A significant positive correlation was found between forced expiratory volume in one second and both the six-minute walk distance (6MWD) (r = 0.489; p = 0.006) and the 30s-STS (r = 0.512; p = 0.004). Forced vital capacity was positively correlated with 6MWD (r = 0.634; p < 0.001), the 30s-STS (r = 0.635; p < 0.001), and biceps brachii muscle strength (r = 0.430; p = 0.018). S-index was associated with the 6MWD (r = 0.477; p = 0.008). PIF was associated with the 6MWD (r = 0.465; p = 0.010) and the 30s-STS (r = 0.482; p = 0.007). Inspiratory volume was also positively associated with the 6MWD (r = 0.490; p = 0.006) and 30s-STS (r = 0.498; p = 0.005). Conclusion: In hemodialysis patients, respiratory function and dynamic inspiratory muscle parameters are associated with exercise capacity and selected measures of peripheral muscle strength.