Age-related changes in muscle thickness and echo intensity of trunk muscles in healthy women: comparison of 20-60s age groups.

The objective of this study was to investigate the age-related changes in muscle thickness and muscle echo intensity of trunk in subjects including wide range of age groups. The subjects were 112 healthy women (age range 20–60s). The rectus abdominis, external oblique, internal oblique, transversus abdominis, erector spinae, and lumbar multifidus muscles were examined. To confirm the differences among the age groups, the linear mixed effect models were performed. There were significant decreases in muscle thickness of the rectus abdominis and external oblique muscles in the 50s and 60s age groups compared to those in the 20s age group, and a significant decrease in muscle thickness of the erector spinae muscle in the 60s age group compared to those in the 20s age group. However, there was no significant difference among the age groups in muscle thickness of other trunk muscles. There were significant increases in echo intensity of the abdominal muscles in other age groups compared to those in the 20s age group, and significant increases in echo intensity of the back muscles in the age groups over 40 compared to those in the 20s group. Our study revealed that muscle quality may be more affected by age than muscle quantity and the effects of aging differ among muscles.