Ultrasound-assessed abdominal fat distribution and its relation to sarcopenia parameters in community-dwelling young older adults: a cross-sectional study.

Background: Ageing is associated with significant changes in body composition, including increased abdominal adiposity and reduced skeletal muscle strength, mass, and physical performance, known as sarcopenia. However, the association of specific abdominal fat distribution in relation to sarcopenia parameters remains poorly understood. Objective: To assess abdominal fat distribution by ultrasound (US) and explore its association with sarcopenia parameters in community-dwelling young older adults aged 60-74 years. Methods: This cross-sectional study (ClinicalTrials.gov: NCT06871384) included 72 participants (68.1% women). Abdominal fat distribution was assessed by US, measuring total abdominal fat, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and VAT/SAT ratio. Muscle strength was evaluated using a hand grip dynamometer, muscle mass indices [skeletal muscle mass Index (SMI) and appendicular skeletal muscle mass index (ASMI)] by BIA and physical performance by gait speed (GS). Linear regression analysis was adjusted by sex, age and physical activity. Results: Participants were 67.11 ± 4.4 years old [68.1% (49/72) women], 86.1% (62/72) were non-sarcopenic, and 71.4% (50/72) were non-obese. After regression analysis, in all population, VAT was positively associated with muscle mass indices. SAT was negatively associated with GS and relative handgrip strength (HGS/BW). In men, VAT was positively associated with ASMI and inversely associated with HGS/BW. In women, SAT was positively associated with ASMI and inversely associated with HGS/BW and GS, whereas VAT was positively associated with SMI and ASMI and inversely associated with HGS/BW. Conclusion: US-assessed abdominal fat distribution showed sex-specific associations with sarcopenia parameters. In men and in women, VAT was positively associated with muscle mass and negatively associated with muscle strength. Whereas in women, SAT was the only fat depot negatively associated with physical performance. These results suggest that abdominal fat distribution may influence physical performance and relative muscle strength in ageing populations, highlighting the importance of evaluating abdominal fat distribution when assessing sarcopenia parameters.