Associations of Adherence to the 24hour Movement Guidelines with Depressive Symptoms and Anxiety: the Mediating Role of Physical Fitness

Background: Mental health problems such as depression and anxiety were increasingly prevalent among students. Emerging evidence links adherence to 24-hour movement guidelines—including adequate physical activity, limited screen time, and sufficient sleep—with improved mental well-being. However, the mechanisms underlying these associations remained poorly understood. Objectives: This study aimed to examine the association of adherence to 24-hour movement guidelines with symptoms of depression and anxiety among Chinese students, and to explore the mediating role of perceived fitness in these relationships. Methods: A cross-sectional survey was conducted among 1674 students (mean age = 11.4 ± 0.8 years; 47.6% boys) from Chinese elementary schools. 24-hour movement behaviours were assessed using validated self-report measures. Mental health outcomes were measured using the Patient Health Questionnaire (PHQ-9) and the Generalized Anxiety Disorder Scale (GAD-7). Perceived fitness was assessed using the International Fitness Scale. Structural equation modelling was used to evaluate direct and indirect pathways, adjusting for relevant covariates. Results: Only 1.4% of participants met all components of the 24-hour movement guidelines. Adherence to the guidelines was significantly associated with lower levels of depressive (β = -0.125) and anxiety symptoms (β = -0.107). Perceived fitness was also significantly associated with reduced symptoms of depression (β = -0.111) and anxiety (β = -0.049). However, the mediating effects of perceived fitness in both models were minimal or not statistically significant (depression symptoms: β = 0.002; anxiety symptoms: β = 0.001). Conclusions: Better adherence to 24hour movement guidelines was associated with fewer symptoms of depression and anxiety in Chinese students. While perceived fitness was independently linked to improved mental health, its mediating role appears limited. Future studies should incorporate objective fitness assessments and explore additional mediating pathways to fully understand how movement behaviours impact students mental well-being.