title: 5-year changes in afterschool physical activity and sedentary behavior.
abstract: BACKGROUND
  The afterschool period holds promise for the promotion of physical activity, yet little is known about the importance of this period as children age.
  
  
  OBJECTIVE
  To examine changes in physical activity of children aged 5-6 years and 10-12 years and their sedentary time in the afterschool period over 3 and 5 years, and to determine the contribution of this period to daily physical activity and sedentary behavior over time.
  
  
  METHODS
  Data from two longitudinal studies conducted in Melbourne, Australia, were used. Accelerometer data were provided for 2053 children at baseline (Children Living in Active Neighbourhoods Study [CLAN]: 2001; Health, Eating and Play Study [HEAPS]: 2002/2003); 756 at 3-year follow-up (time point 2 [T2]); and 622 at 5-year follow-up (T3). Light (LPA), moderate (MPA) and vigorous (VPA) physical activity were determined using age-adjusted cut-points. Sedentary time was defined as ≤ 100 counts/minute. Multilevel analyses, conducted in April 2012, assessed change in physical activity and sedentary time and the contributions of the afterschool period to overall levels.
  
  
  RESULTS
  Afterschool MPA and VPA decreased among both cohorts, particularly in the younger cohort, who performed less than half of their baseline levels at T3 (MPA: T1=24 minutes; T3=11 minutes; VPA: T1=12 minutes; T3=4 minutes). LPA also declined in the older cohort. Afterschool sedentary time increased among the younger (T1=42 minutes; T3=64 minutes) and older cohorts (T1=57 minutes; T3=84 minutes). The contribution of the afterschool period to overall MPA and VPA increased in the older cohort from 23% to 33% over 5 years. In the younger cohort, the contribution of the afterschool period to daily MPA and VPA decreased by 3% over 5 years.
  
  
  CONCLUSIONS
  The importance of the afterschool period for children's physical activity increases with age, particularly as children enter adolescence.
authors.affiliation: Centre for Physical Activity and Nutrition Research (C-PAN), Deakin University, Melbourne, Australia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Arundell
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Ridgers
authors.forename: Jenny
authors.initials: J
authors.lastname: Veitch
authors.forename: Jo
authors.initials: J
authors.lastname: Salmon
authors.forename: Trina
authors.initials: T
authors.lastname: Hinkley
authors.forename: Anna
authors.initials: A
authors.lastname: Timperio
mesh_terms: D056044:Actigraphy / Q000295:instrumentation; D002648:Child; D002675:Child, Preschool; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D057185:Sedentary Behavior; D014739:Victoria