Relationship Between Respiratory Muscle Strength and Physical Performance in Elderly Hospitalized Patients

Background: Age-related changes in pulmonary function increase respiratory muscle work. In the face of this increased demand, poor muscle mass, frequently associated with age and multi-morbidity, can reduce endurance and strength of respiratory muscles. Furthermore, poor muscle mass may per se contribute to exercise intolerance and lower physical performance. The aim of the study was to evaluate if respiratory muscle strength has a significant impact on physical performance in an elderly population. Methods: We included 68 patients (28 men and 40 women) aged over 65 years (mean 79 years, standard deviation [ SD] 6) in stable condition at discharge from our acute care geriatric ward. We assessed the function of respiratory muscle by measuring maximal inspiratory and expiratory pressures (MIP, MEP) and physical function using the 6-Minute Walk Test (6MWT). Results: The mean age of our sample was 78.2 years (SD 6.1). There was a statistically significant correlation between MIP or MEP and 6MWT distance (MIP, r = 0.43, p < 0.001; MEP, r = 0.41, p = 0.001). The association between respiratory pressures and 6MWT was maintained after adjustment for forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), age, sex, fat-free mass index (FFMI), and leg strength. The multiple regression model showed a significant relation between 6-Minute Walk Test distance (6MWD) and both MIP and MEP after correction for sex, age, FEV1, and FVC. Furthermore, MEP can significant predict poorer performance at 6MWD in a multiple logistic regression model. Conclusion: Reduced respiratory muscle strength is independently associated with worse physical performance in elderly patients.