Effect of age on shear modulus, muscle thickness, echo intensity of the upper limb, lower limb, and trunk muscles in healthy women

Abstract

[Purpose] This study aimed to examine the effect of age on the mechanical properties, muscle size, and muscle quality in the upper and lower limb and trunk muscles. [Methods] We evaluated the shear modulus (G), muscle thickness (MT), and echo intensity (EI) of the upper and lower limb and trunk muscles of 83 healthy women (21–83-year-old). The G values of some limb muscles were measured in relaxed and stretched positions. [Results] Regarding the effect of age on G at the distinct positions, the G of the upper limb muscles were not significantly correlated with age in the relaxed and stretched positions. In contrast, the G of the iliacus showed a significant negative correlation in both positions. Additionally, the G of the rectus femoris had a significant negative correlation only in the relaxed position. Regarding differences among body parts, the G of the lower limb and oblique abdominal muscles showed a significant negative correlation, but no correlation in the upper limb, rectus abdominis, and back muscles. Moreover, MT showed a significant negative correlation with age in the lower limb, abdominal, and erector spinae muscles, but no correlation was detected in the upper limb and lumbar multifidus muscles. EI had a significant positive correlation in all the muscles. [Conclusion] The effect of age on G depended on body parts, and the G of the lower limb and oblique abdominal muscles negatively associated with age. Additionally, G in the relaxed position may be more susceptible to aging than G in the stretched position.