Temporal relationship between physical activity, social anxiety, and internet addiction among adolescents: a cross-lagged analysis.

Physical activity (PA), social anxiety (SA), and internet addiction (IA) are closely related to adolescents' psychological and behavioral development, yet their longitudinal directional association Responses to Editor and Reviewers. This study examined the temporal predictive relationships among PA, SA, and IA in adolescents using a cross-lagged panel model. A two-wave longitudinal study with a 16-week interval was conducted among 877 adolescents from three middle schools in Jiangxi Province. PA, SA, and IA were assessed using the Physical Activity Rating Scale (PARS-3), Social Anxiety Scale for Adolescents (SAS-A), and Internet Addiction Test (IAT). Cross-lagged panel analyses were applied to test temporal predictive associations and the role of SA. PA was negatively associated with IA at both time points. PA at T1 positively predicted PA at T2 (β = 0.78, p < 0.001) and negatively predicted IA at T2 (β =  - 0.12, p < 0.001). SA at T1 negatively predicted PA (β =  - 0.03, p < 0.001) and positively predicted both SA (β = 0.50, p < 0.001) and IA at T2 (β = 0.10, p < 0.01). IA at T1 negatively predicted PA (β =  - 0.05, p < 0.001) and positively predicted IA at T2 (β = 0.13, p < 0.001), but not SA. PA, SA, and IA form a longitudinal developmental system in adolescence. PA functions as a protective factor, whereas elevated SA and IA may undermine subsequent PA engagement. Promoting sustained PA may support adolescents' mental health and reduce problematic internet use.