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

## TL;DR

This study finds that over a quarter of US adolescents do not engage in muscle-strengthening exercise, with disparities among girls, older teens, and those with certain health conditions.

## Contribution

The study provides the first 10-year analysis of no muscle-strengthening exercise trends and sociodemographic disparities among US adolescents.

## Key findings

- 28.5% of adolescents reported no muscle-strengthening exercise, with girls and older teens more likely to do none.
- No muscle-strengthening exercise increased from 2011 to 2021 across all demographic groups.
- Adolescents with underweight, overweight, or obesity were more likely to report no muscle-strengthening exercise.

## Abstract

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.