Differential Characteristics of Skeletal Muscle in Community-Dwelling Older Adults

Background: Sarcopenia is diagnosed on the basis of skeletal muscle mass and muscle strength/function. However, more simple and accurate measures for muscle mass and muscle strength/function should be explored. Objective: The aim of this study was to compare the skeletal muscle characteristics at each stage of sarcopenia (normal, presarcopenia, dynapenia, and sarcopenia) via ultrasonography, multifrequency bioelectrical impedance analysis (BIA), and physical assessment batteries in community-dwelling older adults. By evaluating the relationship between muscle quality/quantity indicators and muscle mass/muscle function, we attempted to identify better muscle quantity and quality indicators for the diagnosis of sarcopenia. Setting and subjects: Community-dwelling older men (n = 100, 81.6 +/- 7.4 years) and women (n = 247, 79.7 +/- 6.9 years) participated in this study. Measurements: Skeletal muscle quantity and quality were measured by ultrasonography and multifrequency BIA. Ultrasonographic (thickness and echo intensity) and multifrequency BIA (volume and density) indicators, as well as physical assessment measures, were compared among each stage of sarcopenia. In addition, receiver-operating characteristic analysis was used to assess the sensitivity and specificity of each indicator. Results: Most of the muscle quantity indicators were lower in the sarcopenia and presarcopenia groups than in the other groups, whereas most of the muscle quality indicators were lower in the sarcopenia and dynapenia groups than in the other groups. According to the receiver-operating characteristic analysis, quadriceps muscle thickness and thigh muscle volume were better indicators of muscle mass, whereas the quadriceps muscle echo intensity and thigh muscle density were more robust indicators of muscle function. Conclusions: In this study, we found potential muscle quality and quantity indicators for sarcopenia diagnosis by ultrasonography and multifrequency BIA. Future longitudinal studies are warranted to define the role of these indicators for the diagnosis of sarcopenia. (C) 2017 AMDA - The Society for Post-Acute and Long-Term Care Medicine.