Temporal Variations and Sociodemographic Differences in no Muscle‐Strengthening Exercise Among Adolescents: A 10‐Year Repeated Cross‐Sectional Study

No or low physical activity (PA) is an emerging risk indicator, but existing studies have not focused specifically on the muscle-strengthening exercise (MSE) component of the PA guidelines. The aims of this study are to (1) investigate the prevalence of no-MSE among United States (US) adolescents; (2) examine the sociodemographic correlates of no-MSE; and finally (3) assess the trends in no-MSE from 2011 to 2021. Repeated cross-sectional data from the 2011 to 2021 cycles of the Youth Risk Behavior Surveillance System are used, which include 78 697 US adolescents aged 14-17 years (girls: weighted% = 49.4%). Participants self-reported their sociodemographic variables and days of MSE. No-MSE is operationalized as 0 days of MSE per week. Survey-weighted binary logistic regression models are used to examine the associations between the sociodemographic variables and the prevalence of no-MSE. Estimates are presented as odds ratios (ORs) and their respective 95% confidence intervals (CI). A total of 28.5% of adolescents reported no-MSE, of whom girls [OR = 2.12 (2.02-2.23)], older adolescents aged 16 or 17 years (ORs range = 1.31-1.51, p < 0.001), Black or African American adolescents [OR = 1.14 (1.05-1.24)], and adolescents with underweight, overweight, or obesity (ORs range = 1.18-1.75, p < 0.001) are more likely to report no-MSE, compared to their respective counterparts. No-MSE increased from 2011 to 2021 (p for trend < 0.001), with the trend seen across all sociodemographic subgroups. Over one in four US adolescents do not engage in MSE, with a higher probability of not engaging among specific demographic and health status-based subgroups. Given the rising prevalence of no-MSE and persistent disparities, targeted and tailored interventions as well as equity-oriented policies are urgently needed to expand access to MSE opportunities for US adolescents.