title: Objective Analysis of Preschoolers' Physical Activity Patterns During Free Playtime.
abstract: BACKGROUND
  The purpose of this study was to examine the temporal patterns of preschoolers' physical activity (PA) levels during a typical outdoor free playtime.
  
  
  METHODS
  Baseline playtime accelerometer counts (4.3 ± 0.8 days) from 3 preschool PA intervention studies were used (n = 326 children, age = 4.0 ± 0.8 years). Data were collected using 15-second epochs and classified into sedentary, light, or moderate-to-vigorous physical activity (MVPA). Patterns of change during playtime were analyzed using orthogonal polynomial comparisons.
  
  
  RESULTS
  For all ages, there was a U-shaped pattern of change for the percent of epochs classified as sedentary [F(1, 323) = 47.12, P < .001) and an inverted U-shaped pattern of change for the percent of epochs classified as MVPA [F(1,323) = 32.15, P < .001]. Age-stratified analyses indicated that the 3-year-olds maintained the decrease in sedentary time [F(2,323) = 6.408, P = .002] and the increase in MVPA [F(2,323) = 3.2, P = .04] to a greater extent than the 4- and 5-year-olds.
  
  
  CONCLUSIONS
  Preschool children gradually became more active during the first 10 to 15 minutes of outdoor gross motor playtime and less active over the final 10 to 15 minutes of playtime. During the second half of playtime 3-year-olds maintained these changes to a greater degree than 4- and 5-year-olds.
authors.affiliation: Dept of Kinesiology, University of Massachusetts, Amherst.
authors.forename: Cory J
authors.initials: CJ
authors.lastname: Greever
authors.forename: John
authors.initials: J
authors.lastname: Sirard
authors.forename: Sofiya
authors.initials: S
authors.lastname: Alhassan
mesh_terms: D061725:Accelerometry; D002675:Child, Preschool; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D010988:Play and Playthings