Aging-associated differences between perioral and trunk muscle characteristics.

The physiological and functional changes from aging affect the systemic and swallowing muscles. While ultrasound is used to examine muscle characteristics, no previous studies have examined the relationship between age and perioral and trunk muscle characteristics, including stiffness. This study aimed to investigate the relationship between age and the characteristics of perioral and trunk muscles, including quality, quantity, and stiffness, using ultrasound. A total of 215 participants were recruited for this cross-sectional study: 98 younger adults (20-64 years) and 117 older adults (≥ 65 years). Muscle characteristics were assessed along with data on age, sex, body mass index, and number of teeth. The correlation between age and muscle characteristics was examined. Multiple linear regression was performed with muscle characteristics as dependent variables and age, body mass index, and number of teeth as explanatory variables. We found that only trunk muscle stiffness was associated with age, with a stronger correlation in quality and quantity than perioral muscles. Masseter muscle quality and quantity showed a higher correlation with age than those of the geniohyoid muscle. In conclusion, characteristics of the trunk and perioral muscles exhibit differences in age-related changes, highlighting the importance of maintaining both trunk and perioral muscle activity in older adults to prevent functional decline.