Background: Current guidelines for muscle strengthening activity (MSA) include two or more days per week of physical activities specifically designed to strengthen muscles such as sit-ups, push-ups, or lifting weights. Knowledge regarding subpopulations of adults that are more or less likely to adopt MSA recommendations can be helpful for health promotion programming. The purpose of this study was to examine the sociodemographic predictors of MSA in U.S. adults. Methods: Data for this study came from the CDC's 2022 National Health Interview Survey (NHIS). A total of 27,651 adult participants 18+ years of age were initially included. The primary outcome variable was meeting MSA guidelines status of 2+ days per week of MSA. Sociodemographic predictor variables included age group, sex, race/ethnicity, education, income quartile, marital status, and school status. Poisson regression models with robust error variance were used to compute relative risk (RR) ratios and 95% confidence intervals (CIs). Results: Overall, less than a third of adults met recommended amounts of MSA (30.6%, 95% CI: 29.8 – 31.4) with significant differences (p < .05) found within all sociodemographic variables. Multivariate models showed that male, younger, Black, graduate degree holding, higher income, non married, and school attending adults were significantly more likely to meet MSA guidelines then their respective counterparts. Additionally, an income quartile-by-sex interaction effect (p < .0001) revealed a greater linear trend of modeled predicted probabilities for males across income quartiles than females. Conclusion: These results indicate that several different subpopulations engage in recommended amounts of MSA in greater proportion than others. All disparities remained after adjusting for all other sociodemographic variables. Health promotion and policy efforts to increase MSA should especially be directed toward older, less educated, and lower income adults

Physical activity (PA), Muscle strengthening activity (MSA), NHIS, Demography