Muscle quality characteristics of muscles in the thigh, upper arm and lower back in elderly men and women.

Abstract

The ratio of fat within skeletal muscle is an important parameter that is indicative of muscle quality, and can be assessed using ultrasonography to measure echo intensity (EI). Muscle EI indicates muscle strength and risk of physical dysfunction; however, this observation was determined following examinations of only selected muscle. The purpose of this study was to investigate the EI characteristics of muscles in several regions in elderly men and women, using physical function tests and serum cholesterol levels. Twenty-two men and women (age 78 ± 8years) participated in this study. The EIs were calculated from rectus femoris (RF), biceps femoris (BF) triceps brachii (TB) and multifidus (MF) using B-mode transverse ultrasound images. Seven functional tests (isometric knee-extension peak torque, functional reach, sit-to-stand, 5-m normal/maximal speed walking, handgrip strength and timed up-and-go) and blood lipid components including adipocytokines were measured in all participants. A statistically significant correlation between EI of the RF, TB and BF was observed (r = 0.46-0.50, P < 0.05), but not between EI of the MF and that of other muscles. EI of muscles of the limbs, which was averaged EI for RF, TB and BF, was negatively correlated with leptin levels (adjusted R2 = 0.27, P < 0.01), and EI of the MF was correlated with muscle mass and performance in the timed up-and-go test (adjusted R2 = 0.61, P < 0.01). These results suggest that EI might be influenced by specific parameters depending on the location of the muscle.