Abstract: Objective: To explore the relationship between low physical activity (LPA), moderate-to- vigorous physical activity (MVPA), sedentary behavior (SB) and executive function in preschool children. Methods: 144 preschool-age children were chosen as the research subjects, the accelerometer (ActiGraph GT3X-BT) was used to measure physical activity and sedentary behavior, the parental version of the Children's Executive Function Scale (BRIEF-P) was used to evaluate executive function, correlation analysis, regression analysis, and isotemporal substitution analysis was used to explore the relationship among them. Results: (1) MVPA was significantly negatively correlated with executive function score, while LPA and SB were not significantly correlated with executive function score; (2) After controlling for factors such as gender, age, urban and rural, and wearing time, MVPA still maintains a negative influence on executive function scores, and SB begins to have a positive influence. On this basis, adding control of SB or MVPA, only MVPA and VPA still have significant influence on the inhibition function; (3) After MVPA replaces SB isochronously, preschool children's inhibition, refresh, inhibition of self-control, metacognition scores and total score of executive function all decreased significantly, in contrast, all increased significantly; (4) After MVPA isochronously replaced LPA, the score of inhibitory function decreased significantly, but the score change in other executive function dimensions was not significant. Conclusion: The MVPA objectively monitored by the accelerometer is closely related to the executive function, especially the inhibitory function of preschool children. Promoting the appropriate conversion of SB and LPA, especially SB to MVPA, can effectively improve the executive function performance of preschool children.

Key words: preschool children, physical activity, sedentary behavior, executive function