Tissue-specific body composition changes and muscle performance decline: a 5-year prospective study

OBJECTIVE: The change of muscle performance plays an important role in sarcopenia. Our objective was to examine longitudinal changes in body composition in older individuals in relation to changes in physical performance. METHODS: 120 individuals were recruited from the neighborhood of the hospital. Computed tomography (CT) scans, handgrip strength (HGS) and the Timed Up and Go test (TUG) were obtained at baseline and follow-up after 5 years. Changes in muscle cross-sectional area and muscle density and adipose area were evaluated. Associations of changes in body composition with changes in HGS and TUG were tested in logistic regression models after adjusting for baseline age, height, weight and type 2 diabetes. RESULTS: Among females, each decrease (per cm²) of anterior compartment of thigh muscle size was associated with a 101% decrease of HGS (95% confidence interval [CI], 1.10-3.67; P = 0.02) and an 121% longer TUG (95%CI, 1.16-4.24; P = 0.02). Among males, each decrease (per HU) of psoas major muscle density (OR, 0.37; P = 0.04) would decrease the risk of decreased HGS. CONCLUSIONS: CT-based body composition changes, atrophy of thigh muscles in particular, are associated with loss of muscle strength and physical performance. ADVANCES IN KNOWLEDGE: Key findings include significant reductions in muscle size and density across multiple compartments (paraspinal, pelvic and thigh muscles), greater adipose tissue increase in females, and sex-specific associations between thigh muscle atrophy and declines in HGS and TUG performance. These results align with prior cross-sectional evidence of age-related sarcopenia but extend them by quantifying longitudinal changes and their functional consequences.