PURPOSE This study identified physical activity patterns among adolescents using latent class analysis (LCA) and examined their associations with mental health outcomes. METHODS Complete data were obtained from 53,350 middle and high school students who participated in the 2024 Korea Youth Risk Behavior Survey. Physical activity variables were moderate-intensity activity, vigorous-intensity activity, muscle-strengthening exercise, and sedentary behavior. Mental health indicators were stress, postsleep fatigue, depression, suicide risk, loneliness, and anxiety. Physical activity patterns were identified using LCA, and their associations with mental health outcomes were assessed using logistic regression. Model selection was based on the Bayesian information criterion, and statistical significance was set at p < .05. RESULTS Male students reported significantly higher physical activity levels than female students (p < .001), whereas female students reported higher vulnerability to stress, depression, suicide risk, loneliness, and anxiety (p < .001). Through LCA, two distinct classes were identified in all groups: “sedentary behavior-centered” and “physical activity-centered.” Notably, most adolescents failed to meet national physical activity guidelines. Logistic regression results showed that the sedentary group was more likely to experience stress (male middle school students: OR = 1.16, 95% CI = 1.07–1.25; male high school students: OR = 1.39, 95% CI = 1.26–1.53; female high school students: OR = 1.50, 95% CI = 1.21–1.83), and male high school students experienced worse anxiety (OR = 1.50, 95% CI = 1.20–1.89). CONCLUSIONS Findings highlight the importance of tailored interventions promoting adolescent mental health through improved physical activity. Studies may adopt gender-specific approaches to account for distinct activity and mental health profiles and increase the effectiveness of health promotion strategies.
