Acute effects of a single recess physical activity session on sustained attention among junior high school students: a randomized controlled trial based on in-class task performance

Objectives This randomized controlled trial explored the acute effects of a single recess physical activity session on junior high school students’ sustained attention, examined the chain mediating roles of executive function and academic engagement, and aimed to inform optimal recess arrangements. Methods A total of 168 junior high school students from two public schools, stratified by grade and sex, were randomly assigned to an experimental group (20 min of moderate-to-vigorous physical activity during recess) or a control group (sedentary recess). Sustained attention was assessed at baseline and post-intervention using the d2 Test. Post-intervention measures included executive functioning (BRIEF-SR) and academic engagement (behavioral observations). Data were analyzed using a mixed-design ANOVA to assess the time and condition effects. Chain mediation was examined using the PROCESS macro (Model 6, 10, 000 bootstrap samples) and structural equation modeling with maximum likelihood estimation. Results Demographic analyses indicated higher physical activity intensity in males and better executive functioning in ninth graders, with no group differences in academic engagement or sustained attention at baseline. Mixed-design ANOVA revealed significant group × time interactions for sustained attention F (1, 166) = 18. 42, p 0. 001, η 2 p = 0. 10, executive functioning F (1, 166) = 12. 56, p 0. 001, η 2 p = 0. 07, and academic engagement F (1, 166) = 14. 89, p 0. 001, η 2 p = 0. 08. The experimental group showed greater improvements in sustained attention (ΔM = 8. 73 vs. −2. 15), executive functioning (ΔM = 5. 24 vs. 0. 87, Mₚost = 54. 3, SD = 8. 1 vs. Mₚost = 49. 1, SD = 7. 9), and academic engagement (ΔM = 12. 6% vs. 1. 8%, Mₚost = 84. 9%, SD = 10. 3% vs. Mₚost = 73. 2%, SD = 11. 5%) than did the control group. Chain mediation modeling supported indirect effects through executive functioning alone (β = 0. 09), academic engagement alone (β = 0. 11), and their sequential pathway (β = 0. 08, 95% CI 0. 045, 0. 128), with total indirect effects explaining 60. 9% of the total effect. Conclusion A single moderate-to-vigorous physical activity session during recess acutely enhances junior high school students’ sustained attention, mediated sequentially by executive functioning and academic engagement. However, the simultaneous measurement of mediators suggests that these findings should be replicated using longitudinal designs featuring temporally separated assessments.