This study examined how the size of playground in the nursery school is related to children's levels of physical activity in playing outdoor (in the playground and outside of the school) and physical ability. We measured physical activity levels of 42 children at 3, 4, and 5 years old, by accelerometer during nursery care for ten days.

We found the following:

(1) that the steps/hour of children at School B with a larger playground was higher than that of children at School A with a smaller playground in 3 and 4 years old, but was not in 5 years old, and

(2) that there was a significant difference between two schools running-activity (LC7-9) time at all ages; School B was more than School A, however,

(3) as a result of two-way ANOVA (schools vs ages) for physical ability, main effect by schools was not significant between two schools, main effect by ages was significant, and

(4) there was a cross-correlation between steps/hour at 3 years old and jumping over at 4 years old, a running-activity time at 3 years old and jumping over at 4 years old.

The playground size did not affect the physical ability, but it affected an activity levels in the playground, which was related to outdoor play in the playground and outside of the school). In conclusion, that outdoor play outside the school is not a substitute for outdoor play in the playground.

This study examined how the size of playground in the nursery school is related to children's levels of physical activity in playing outdoor (in the playground and outside of the school). We compared two nursery schools, School A with a smaller playground and School B with a larger playground. A total of 42 children (20 children from School A；22 children from School B) participated.

We observed children's outdoor play for ten days in the morning and measured physical activity levels by accelerometer. We found the following：

(1) that the activity level of children at School A with a smaller playground was lower than that of children at School B with a larger playground, and

(2) that outside-of-the-school outdoor play is associated with higher activity levels than outdoor play in the school playground, however,

(3) that both schools did outside-of-the-school outdoor play only once during the two week observation period.

Given the vital importance of providing children with enough outdoor play, we must address playground size and use of outside-of-the-school outdoor play.