Association between physical activity, smartphone usage, and obesity risk among Korean adolescents: A cross-sectional study based on 2021 Korean adolescent health behavior survey

The findings reveal complex relationships between PA, MSE, sedentary behavior, and smartphone usage in the context of adolescent obesity. Certain PA levels, particularly 3-4 times/week and ≥ 5 times/week for females, and HIPA frequency were associated with increased obesity risk. In contrast, MSE significantly reduced obesity risk across genders, with the most substantial effects observed in males engaging in MSE ≥ 5 times/week. Only associations meeting the p < 0.01 threshold were interpreted in this study to ensure robust conclusions. These results emphasize the importance of promoting MSE and balanced sedentary behavior patterns to reduce adolescent obesity risk, suggesting health policies should address these factors with a focus on gender-specific and age-specific strategies. However, limitations such as the lack of nutrition data, unassessed PA intensity, and HIPA duration should be addressed in future research.