Frequency profiles of muscle-strengthening exercise identified using three national surveillance measures in a convenience sample of adults

Muscle-strengthening exercise (MSE) is crucial for health, with current guidelines recommending engaging in MSE at least two times per week. In the US, the National Health and Nutrition Examination Survey (NHANES), National Health Interview Survey (NHIS), and Behavioral Risk Factor Surveillance System (BRFSS) assess MSE frequency, however, research on frequency-based adherence is limited. The

Purpose: of this study is to identify and describe subgroups of MSE participation based on frequency responses to NHANES, NHIS, and BRFSS MSE survey items. In this cross-sectional analysis, a convenience sample of participants ( n = 118 [male = 54, female = 64], mean age [±standard deviation] = 27.0 ± 10.7 years) completed an MSE questionnaire at two time points approximately one week apart that included MSE frequency items from the NHANES, NHIS, and BRFSS. Latent profile analysis (LPA) was conducted on data from the first time point to identify latent MSE frequency subgroups, while bootstrap likelihood ratio tests (BLRT; B = 5,000) were utilized to help determine the optimal number of profiles. The LPA indicated a three-profile solution as the best overall fit based on the difference in Bayesian information criterion, strong relative entropy (0.980), and adequate profile distribution ( p 1 = 28.8%, p 2 = 50.0%, p 3 = 21.2%). The BLRT supported the three-profile solution, with the addition of a third profile significantly improving fit compared to the two-profile model ( p < 0.001). Profiles were labeled based on the average times per week of MSE. They included, (1) Minimal Participation With No Guideline Adherence (0.23 ± 0.43 times per week), (2) Moderate Participation With Guideline Adherence (3.30 ± 0.74 times per week), and (3) High Participation With Guideline Adherence (5.53 ± 0.66 times per week). Three distinct MSE frequency profiles were identified in this convenience sample, with 71.2% of participants classified into guideline-adherent profiles, substantially higher than national estimates of <30%. Within this sample, the identification of two guideline-adherent frequency profiles suggests that binary classification may mask variability in MSE frequency among individuals meeting current guidelines. These

Findings: should be validated in nationally representative samples.