Handgrip Strength in Korean Youth and Young Adults: Reference Values and Their Associations with Metabolic Syndrome

Background: Reduced handgrip strength (HGS) is associated with adverse cardiometabolic outcomes. This study aimed to determine reference values for HGS among Korean youth and young adults and to evaluate their relationships with metabolic syndrome (MS). Methods: We analyzed data from 9,024 individuals aged 10 to 29 years in the Korea National Health and Nutrition Examination Survey (2014-2019). The adjusted combined handgrip strength (aCHGS; the average of maximum values from both hands divided by body weight) was used as the primary outcome variable. Percentile curves for aCHGS were generated using the lambda-mu-sigma (LMS) method and locally estimated scatterplot smoothing regression analysis, excluding outliers. Associations between aCHGS z-scores and MS were assessed. Results: Percentile curves for aCHGS plateaued after 20 years of age in both sexes. At age 10, aCHGS was comparable between males and females. Males showed a marked rise in aCHGS after early adolescence, maintaining higher levels thereafter. The adjusted odds ratio for MS was 0.313 (95% confidence interval [CI], 0.276 to 0.354) using International Diabetes Federation (IDF) criteria and 0.348 (95% CI, 0.310 to 0.390) using modified National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) criteria. aCHGS z-scores demonstrated strong predictive power for MS (area under the curve, 0.802 for IDF and 0.776 for modified NCEP-ATP III criteria). The optimal aCHGS z-score cutoff values for predicting MS were -0.508 (IDF) and -0.519 (modified NCEP-ATP III). Conclusion: We established age- and sex-specific aCHGS reference values among Korean youth and young adults, demonstrating effectiveness in predicting MS risk. These standards may serve as a practical clinical tool to identify individuals at increased risk of MS early in development.