Relation Between Respiratory Muscle Strength and Skeletal Muscle Mass and Hand Grip Strength in the Healthy Elderly

Objective To evaluate sarcopenic indices in relation to respiratory muscle strength (RMS) in elderly people. Methods This study included 65 volunteers over the age of 60 (30 men and 35 women). The skeletal muscle mass index (SMI) was measured using bioimpedance analysis. Limb muscle function was assessed by handgrip strength (HGS), the Short Physical Performance Battery (SPPB), and gait speed. RMS was addressed by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) using a spirometer. The relationships between RMS and other sarcopenic indices were investigated using the Pearson correlation coefficients and multiple regression analysis adjusted for age, HGS, and SPPB. Results Both MIP and MEP were positively correlated with SMI (r=0.451 and r=0.388, respectively, p<0.05 in both). HGS showed a significant correlation with both MIP and MEP (r=0.560, p<0.01 and r=0.393, p<0.05, respectively). There was no significant correlation between gait speed and either MIP or MEP. The SPPB was positively correlated with MEP (r=0.436, p<0.05). In the multiple regression analysis, MIP was significantly associated with HGS and SMI (p<0.001 and p<0.05, respectively), while MEP was related only with HGS (p<0.05). Conclusion This study suggests that respiratory muscles, especially inspiratory muscles, are significantly related to limb muscle strength and skeletal muscle mass. The clinical significance of MIP and MEP should be further investigated with prospective studies.