Accelerated biological aging and risk of sarcopenia: evidence from 29,000 Chinese adults

To construct biological age (BA)-based normative curves for muscle mass and strength and to determine whether biological age acceleration is associated with impaired muscle health and sarcopenia across adulthood. A total of 29,437 adults aged 20-80 years were analyzed from the China National Health Survey (2023-2024). BA was estimated using the Klemera-Doubal method (KDM) based on clinical biomarkers, and BA acceleration (BAacc) was defined as the residual of BA regressed on chronological age (CA). Appendicular skeletal muscle mass (ASM) and appendicular skeletal muscle mass index (ASMI) were assessed by bioelectrical impedance analysis, while handgrip strength (HGS) and relative handgrip strength (rHGS) were measured by dynamometer. Sex-specific BA-based percentile curves were generated using the Lambda-Mu-Sigma (LMS) method. Logistic regression models evaluated associations of BAacc with low muscle mass (LMM), low muscle strength (LMS), and sarcopenia. BA-based percentile curves revealed steady, sex-specific declines in ASM, ASMI, HGS, and rHGS across BA. Each one-year increase in BAacc was associated with significant reductions in ASMI (β = -0.0064 in men; -0.0041 in women) and rHGS (β = -0.0132 in men; -0.0064 in women) (all p < 0.0001). Accelerated BA (BAacc > 0) was linked to higher odds of LMM (73-77%), LMS (34-37%), and sarcopenia (68-78%), with dose-response relationships across quartiles. Associations were particularly pronounced in adults < 60 years, indicating that biological aging impacts muscle health earlier than the conventional threshold for old age. BA acceleration was strongly associated with impaired muscle mass, strength, and sarcopenia, with stronger effects observed in women and in younger adults. BA-based reference curves demonstrated clear, sex-specific declines in muscle health across adulthood, providing a novel reference framework for future sarcopenia research.