Association of handgrip strength asymmetry and weakness with intrinsic capacity impairment among older adults in China

Declining intrinsic capacity (IC) significantly impacts health outcomes in aging populations. While weak handgrip strength (HGS) is associated with IC impairment, the role of HGS asymmetry remains unclear, especially among older Chinese cohorts. We included participants aged ≥60 years from the 2015 wave of the China Health and Retirement Longitudinal Study (CHARLS). IC was evaluated across cognitive, locomotion, psychological, sensory, and vitality domains. Asymmetry and weakness were measured using the maximum value of HGS. Logistic regression models were employed to examine the association of the individual and combined groupings of HGS asymmetry and weakness with IC impairment (a total score ≥ 2 across five domains). The potential non-linear relationship was explored using a restricted cubic spline (RCS) model. Of the 4798 participants included (median age 66.0 years, IQR 63.0-71.0 years; 56.9 % male), 35.2 % had IC impairment. HGS asymmetry (OR = 1.26, 95 % CI: 1.11-1.43) and weakness (OR = 2.09, 95 % CI: 1.78-2.45) were both independent risk factors for IC impairment. Notably, participants experiencing both HGS asymmetry and weakness were at even higher risk of IC impairment (OR = 2.47, 95 % CI: 1.99-3.08), suggesting compounded effects on IC. Further subgroup analysis showed significant associations between HGS status and impairments in specific IC domains, particularly in locomotion. In contrast to other domains, it was the Weakness only group, rather than the Both group, that had the highest risk of vitality impairment. There was a U-shaped relationship between HGS asymmetry and IC impairment. HGS asymmetry and weakness were associated with an increased risk of composite and individual domain IC impairment. Assessing and maintaining HGS symmetry and strength may have implications for the early identification of individuals at risk for IC impairment and the prevention of related adverse health outcomes.