title: Objective assessment of levels and patterns of physical activity in preschool children.
abstract: BACKGROUND
  The aim of this study was to examine in detail levels and patterns of physical activity in preschool children and the effects of gender and BMI on this activity.
  
  
  METHODS
  Two hundred and fifty-three children aged 5 y participating in the Copenhagen Prospective Studies on Asthma in Childhood wore an accelerometer day and night over a 4-wk period. The main outcome measure was level of physical activity using the raw data. A secondary measure was time spent in moderate to vigorous physical activity (MVPA). A Fourier series analysis was applied to study in detail patterns over time.
  
  
  RESULTS
  Activity profiles throughout the year were unique for each sex, with boys being overall more active than girls except for winter months. Preschool children also showed distinct patterns of physical activity during weekdays as compared with weekends and were most active during weekdays. Preschool children in the highest tertile of BMI had a flat yearly activity profile and tended to be less active as compared with those in the lowest tertile.
  
  
  CONCLUSIONS
  Preschool children showed significant gender differences in physical activity, with distinct patterns throughout the year as well as between weekdays and weekends. A high BMI tended to be associated with lower levels of physical activity.
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Danish Pediatric Asthma Center, Faculty of Health Sciences, Copenhagen University Hospital Gentofte, Gentofte, Denmark. mbrasholt@hotmail.com
authors.forename: Martin
authors.initials: M
authors.lastname: Brasholt
authors.forename: Bo
authors.initials: B
authors.lastname: Chawes
authors.forename: Eskil
authors.initials: E
authors.lastname: Kreiner-Møller
authors.forename: Signe
authors.initials: S
authors.lastname: Vahlkvist
authors.forename: Marianne
authors.initials: M
authors.lastname: Sinding
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D061725:Accelerometry; D015992:Body Mass Index; D002675:Child, Preschool; D003718:Denmark; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012737:Sex Factors; D013997:Time Factors