Physical activity among Norwegian preschoolers varies by sex, age, and season.

Boys were consistently more active and less sedentary than girls, and PA increased with age for both sexes. Boys exhibited a greater increase than girls in PA by age, and PA differed across seasons, with higher levels of MVPA during spring/summer. Differences in MVPA between boys and girls, among age groups, and among seasons seem to be interrelated, indicating that many factors influence preschoolers' PA.