Variations in Preschoolers' Physical Activity Across the School Year

This study aimed to examine (seasonal) variations in preschoolers' physical activity (PA) across the school year when a PA intervention was versus was not in place and whether patterns of change in PA behavior varied between boys and girls. Kiddie Children and Teachers on the Move, a 30-min structured program designed to engage preschoolers in PA during the school day, was implemented 2-4 times per week for 19-22 wk. PA was measured by accelerometry during the school day during five assessment periods (3 with- and 2 w/no intervention). A total of 90 children (M-age = 4.12 +/- 0.63, 47 males, 43 females) were included in analyses. A series of 5 (time) x 2 (sex) mixed-model ANOVA was used to examine PA across assessments and whether patterns of change in PA varied by sex. Significant variation in total PA was observed over the school year (F-4,F- 352 = 16.35, P < 0.001). Total PA during both nonintervention periods was significantly lower than all three intervention periods (all Ps < 0.01). Similar patterns emerged for moderate-to-vigorous PA and compliance with the Institute of Medicine PA guideline for preschoolers. Significant effects of time were not qualified by the time-sex interaction in any model, suggesting that the pattern of change in PA over time did not vary as a function of sex. Follow-up analyses revealed sex differences in PA behavior within assessment periods. Boys' total and moderate-to-vigorous PA were significantly greater than girls during nonintervention periods; notably, there were no significant sex differences in these PA behaviors during intervention periods. Findings highlight the importance of structured programs to promote preschoolers' PA, especially during winter months when PA seems to decline.