Associations of Life’s Essential 8 with Low Muscle Mass Mediated by Testosterone, Inflammation and Nutritional Status in US Adults: A Cross-Sectional Study

Background Low muscle mass, defined as appendicular lean mass adjusted for body mass index (BMI), may indicate early skeletal muscle deterioration. Objective This study aimed to investigate the relationship between Life's Essential 8 (LE8), the updated cardiovascular health (CVH) metrics by the American Heart Association (AHA), and low muscle mass, including the impact of related biomarkers on muscle quality. Methods This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) cycles 2011-2014, selected due to their inclusion of the most recent appendicular lean mass measurements available in the NHANES dataset. Participants aged 20-60 years were included. We employed weighted logistic regression models, restrictive cubic splines (RCS), and weighted quantile sum (WQS) regression to assess the relationship between LE8 scores and low muscle mass. Four mediation models were constructed to explore whether serum testosterone in males, serum sex hormone-binding globulin (SHBG) in females, serum albumin, and systemic immune-inflammation index (SII) mediated the association between LE8 scores and low muscle mass. Results Higher LE8 scores are associated with lower odds of low muscle mass. Compared to participants with low cardiovascular health (CVH), those with intermediate and high CVH had 49% (Odds ratio (OR) 0.51, 95% confidence interval (CI) 0.30, 0.87) and 86% (OR 0.14, 95%CI 0.06, 0.29) lower odds of low muscle mass, respectively. Mediation analysis revealed that testosterone, SHBG, SII, and albumin partially mediated the association between LE8 scores and low muscle mass. The WQS regression model indicated that BMI and physical activity might be important factors influencing low muscle mass within the components of LE8. Conclusions LE8 scores negatively associated with low muscle mass in US adults. Serum testosterone in males and SHBG in females were negative predictors of low muscle mass, while SII was inversely associated. Serum albumin had a beneficial effect on muscle mass.