Abstract
BACKGROUND: Handgrip strength (HGS) weakness and asymmetry are both abnormal conditions of upper-limb muscle strength. The association between HGS weakness and physical performance is controversial, and the link between HGS asymmetry and physical performance remains unclear. AIMS: This study aimed to investigate the associations of HGS weakness and asymmetry separately and concurrently with low physical performance among Chinese older people. METHODS: The study used two waves of data from China Health and Retirement Longitudinal Study (CHARLS) in 2013 and 2015. HGS weakness and asymmetry were defined according to the maximal HGS and the HGS ratio, respectively. Participants were classified into 4 groups according to HGS status: normal, asymmetry only, weakness only, and concurrent weakness and asymmetry. The logistic regression model was used to investigate the cross-sectional association between low physical performance and each of maximal HGS, HGS ratio, and HGS status, as well as the prospective association between baseline HGS status and new-onset physical performance decline after two years. RESULTS: Participants with HGS asymmetry only, weakness only, and two abnormalities showed a higher prevalence of low physical performance when asymmetry defined as an HGS ratio exceeding 1.20 and 1.30 (all, p < 0.001), with the greatest odds in those with two abnormalities (20% threshold: OR 3.83; 30% threshold: OR 5.41). The longitudinal analysis found that HGS weakness can predict the new-onset low physical performance over a two-year period, with concurrent HGS asymmetry further increased the future risk of physical performance decline. CONCLUSIONS: Both HGS weakness and asymmetry were associated with a higher prevalence of low physical performance, in an additive way. This study will help screen older people with low physical performance more efficiently, and identify those at higher risk of developing new-onset physical performance decline within two years.