Relative Grip Strength as a Screening Indicator for Metabolic Syndrome in Korean Adults: A Cross-Sectional Study Using Data from KNHANES

<i>Background and Objectives</i>: This study aimed to assess the association between relative grip strength (RGS) and metabolic syndrome (MetS) in Korean adults and to explore sex- and age-specific cutoff values for screening purposes. <i>Materials and Methods</i>: This cross-sectional study analyzed data from 12,072 Korean adults (aged 19-64 years) who participated in the 2017-2019 Korea National Health and Nutrition Examination Survey. Receiver operating characteristic (ROC) curve analysis was performed stratified by sex and age group, and participants were categorized into adequate (ARG) and low (LRG) RGS groups. Multivariable logistic regression was used to examine the association between RGS (as both categorical and continuous variables) and MetS, adjusting for lifestyle and behavioral covariates. <i>Results</i>: The RGS demonstrated moderate discriminatory power for MetS, with area under the curve (AUC) values ranging from 0.601 to 0.742. Age- and sex-specific cutoff values for RGS progressively decreased with age. Individuals in the LRG group had significantly higher odds of MetS across all age and sex groups. The LRG group had significantly greater odds of MetS in nearly all subgroups (e.g., women aged 20-39 years: odds ratio [OR] = 6.846; men: OR = 3.502). As a continuous variable, each 0.1-unit increase in RGS was associated with a 22.1-33.4% reduction in the odds of MetS (<i>p</i> < 0.001). <i>Conclusions</i>: RGS is inversely associated with MetS, particularly in women and younger adults. Although its discriminatory ability is moderate, the RGS may serve as a simple and accessible screening indicator to help identify individuals with an increased metabolic risk.