Early childhood education settings are critical for promoting physical activity (PA) but intervention effects are often small. The aim of this study was to develop, test, and compare two approaches to increasing physical activity among preschoolers at child care centers: one focused on a teacher-led PA curriculum (Active Play!) and the other on increasing outdoor child-initiated free play time (Outdoor Play!). We conducted a matched-pair cluster-randomized study in 10 centers in and around Seattle, WA, USA (n = 97 children, mean age 4.6). Pre- and post-intervention data were collected from observations and accelerometers. At pre-intervention, 19% of Active Play! and 25% of Outdoor Play! children achieved >120 min/day of PA during child care. The total opportunity for PA increased in both interventions (Active Play! = 11 min/day; Outdoor Play! = 14 min/day), with the largest increase in outdoor child-initiated free playtime (Active Play! = 19 min/day; Outdoor Play! = 24 min/day). No changes in sedentary time, light or moderate- to vigorous-intensity PA (MVPA) were observed in either intervention and there was no difference between interventions in the percentage of children attaining more than 120 min/day of PA. A small (<3 min/day) relative increase in teacher-led outdoor activity was observed in the Active Play! intervention. Both intervention strategies led to an increase in active play opportunities, predominantly outdoors, but neither was able to substantially increase the intensity and/or duration of children's PA. Future studies are needed to better understand and inform sustainable approaches to increase PA in early learning settings.
Keywords: active play; child care; outdoors; physical activity; preschool.