title: Objectively measured physical activity in four-year-old British children: a cross-sectional analysis of activity patterns segmented across the day.
abstract: BACKGROUND
  Little is known about preschool-aged children's levels of physical activity (PA) over the course of the day. Using time-stamped data, we describe the levels and patterns of PA in a population-based sample of four-year-old British children.
  
  
  METHODS
  Within the Southampton Women's Survey the PA levels of 593 4-year-old children (51% female) were measured using (Actiheart) accelerometry for up to 7 days. Three outcome measures: minutes spent sedentary (<20 cpm); in light (LPA: ≥20-399 cpm) and in moderate-to-vigorous activity (MVPA: ≥400 cpm) were derived. Average daily activity levels were calculated and then segmented across the day (morning, afternoon and evening). MVPA was log-transformed. Two-level random intercept models were used to analyse associations between activity level and temporal and demographic factors.
  
  
  RESULTS
  Children were active for 67% (mean 568.5 SD 79.5 minutes) of their daily registered time on average, with 88% of active time spent in LPA. All children met current UK guidelines of 180 minutes of daily activity. There were no differences in children's average daily levels of sedentary activity and LPA by temporal and demographic factors: differences did emerge when activity was segmented across the day. Sex differences were largest in the morning, with girls being more sedentary, spending fewer minutes in LPA and 18% less time in MVPA than boys. Children were more sedentary and less active (LPA and MVPA) in the morning if they attended childcare full-time compared to part-time, and on weekend mornings compared to weekdays. The reverse was true for weekend afternoons and evenings. Children with more educated mothers were less active in the evenings. Children were less sedentary and did more MVPA on summer evenings compared to winter evenings.
  
  
  CONCLUSIONS
  Preschool-aged children meet current physical activity guidelines, but with the majority of their active time spent in LPA, investigation of the importance of activity intensity in younger children is needed. Activity levels over the day differed by demographic and temporal factors, highlighting the need to consider temporality in future interventions. Increasing girls' morning activity and providing opportunities for daytime activity in winter months may be worthwhile.
authors.affiliation: UKCRC Centre of Excellence for Diet and Activity Research (CEDAR), Box 296, Institute of Public Health, University of Cambridge, Cambridge, UK. krh40@medschl.cam.ac.uk.
authors.forename: Kathryn R
authors.initials: KR
authors.lastname: Hesketh
authors.forename: Alison M
authors.initials: AM
authors.lastname: McMinn
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Sharp
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Collings
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Harvey
authors.forename: Keith M
authors.initials: KM
authors.lastname: Godfrey
authors.forename: Hazel M
authors.initials: HM
authors.lastname: Inskip
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
authors.forename: Esther M F
authors.initials: EM
authors.lastname: van Sluijs
mesh_terms: D061725:Accelerometry; D000203:Activities of Daily Living; D015992:Body Mass Index; D001835:Body Weight; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D009043:Motor Activity; D011446:Prospective Studies; D057185:Sedentary Behavior; D006113:United Kingdom; D044465:White People