The mediating role of physical fitness index in the relationship between screen time and executive function in adolescents: the moderating role of gender

This study aimed to examine the moderating mediating role of adolescent gender and the mediating effect of physical fitness on screen time and executive function. Conducted from September to December 2024, the study recruited 3639 adolescents from six cities - Yantai, Changzhi, Jishou, Xianyang, Kunming, and Changchun - representing China's six major administrative regions. Screen time was assessed using the Physical Activity Level Evaluation for Children and Adolescents Aged 7-18Years. Physical fitness was evaluated via a fitness index calculated from seven physical fitness test indicators. Executive function was measured using a task-prompted paradigm. Physical fitness index mediated the relationship between screen time and working memory reaction times (1-back, 2-back). In the 1-back task, the indirect effect size was 3.281, accounting for 14.58% of the total effect. The indirect effect in the 2-back task was 1.190, accounting for 7.54% of the total effect. Additionally, gender moderated the relationship between adolescent screen time and 1-back task reaction time. and the relationship between adolescent screen time and reaction time on the 2-back task without gender moderation. Physical fitness index partially mediates the relationship between screen time and working memory in adolescents, and gender moderates the association between physical fitness index and 1-back reaction time.