Effects of preschool staff professional development in physical activity on self-regulation, executive function and early academic learning in 3-5-year-old children: The active learning Norwegian preschool(er)s (ACTNOW) cluster-randomized controlled trial.

We aimed to investigate the effects of preschool staff physical activity (PA) professional development on self-regulation, executive function and early academic learning in 3-5-year-old children. A total of 1265 children from 46 preschools in Norway were randomized to a 7-month intervention or control. Main analyses included 816 3-4-year-olds who provided data at baseline, 7- and 18-month follow-ups. We measured children's self-regulation (Head-Toes-Knees-Shoulders task), inhibition, cognitive flexibility, working memory, early expressive vocabulary, early mathematical skills (Early Years Toolbox) and physical activity (accelerometry). Linear mixed models were used to analyze the data. Results showed no effect of the intervention on cognitive or learning outcomes in the primary analyses. We found small positive effects on sedentary time (standardized effect size (ES)=-0.17,  = 0.014) and moderate to vigorous-intensity PA (ES = 0.15,  = 0.048) at 7 months, and a negative effect on low-intensity PA at 18 months (EF = -0.15,  = 0.021). Boys had a small positive effect on vocabulary at 7 months (ES = 0.23,  = 0.006), and girls a small negative effect at 18 months (ES = -0.23,  = 0.004). This cluster RCT in preschoolers supports the notion that pragmatic trials within educational settings have difficulties in providing changes to the PA practice and to impact young children's cognitive development and learning.