title: How do school-day activity patterns differ with age and gender across adolescence?
abstract: OBJECTIVE
  A knowledge of how young people use their time could be instrumental in informing health interventions, modeling consumer behaviors, and planning service delivery. The aim of the present study was to describe age- and gender-related patterns in the self-reported use of time on school days in a large sample of Australian children and adolescents aged between 10 and 18 years.
  
  
  METHODS
  A single, detailed use-of-time diary for a school day was collected from 6024 Australians aged 10-18 from several state and regional surveys conducted in the states of South Australia (SA) and Victoria between 2001 and 2006. Time-use profiles were analyzed for a range of active and sedentary state behaviors.
  
  
  RESULTS
  Boys reported higher physical activity levels (PALs), moderate-to-vigorous physical activity (MVPA), and sports than girls. There were no differences in free play, and girls used more active transport. All activity-related variables decreased with age, except active transport, which peaked at 14-15 years. Boys exhibited higher levels of screen time, whereas girls had higher levels of passive transport. Screen time and its components (television, videogames, and computer use) peaked in the peripubertal years.
  
  
  CONCLUSIONS
  Age- and gender-related patterns of time use vary greatly within adolescence. This may reflect a mix of biological and social factors.
authors.affiliation: Nutritional Physiology Research Centre, University of South Australia, Adelaide, Australia. timothy.olds@unisa.edu.au
authors.forename: Tim
authors.initials: T
authors.lastname: Olds
authors.forename: Melissa
authors.initials: M
authors.lastname: Wake
authors.forename: George
authors.initials: G
authors.lastname: Patton
authors.forename: Kate
authors.initials: K
authors.lastname: Ridley
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Waters
authors.forename: Joanne
authors.initials: J
authors.lastname: Williams
authors.forename: Kylie
authors.initials: K
authors.lastname: Hesketh
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000367:Age Factors; D015992:Body Mass Index; D002648:Child; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D012650:Self Disclosure; D012737:Sex Factors; D013334:Students