title: Physical activity temporal trends among children and adolescents.
abstract: OBJECTIVE
  It is particularly important to measure trends in physical activity to identify specific contexts where physical activity may have declined and can be targeted for intervention. The aim of this review was to summarize overall physical activity trends based on objectively measured physical activity as well as trends in specific contexts (active transport, organized sport, school physical education and school play periods) using self- or proxy-reported physical activity.
  
  
  METHODS
  A comprehensive literature search was completed to identify articles on the specific contexts of physical activity for inclusion in this review.
  
  
  METHODS
  Journal articles for inclusion in this narrative review were sourced from the various databases and reference lists. Most studies in this review employed self-report or proxy-report methodologies.
  
  
  RESULTS
  There is limited research on temporal trends in children's and adolescents' physical activity. The few studies that employ objective measures to assess trends in physical activity indicate little change has occurred in the last 20 years. Other studies that employed self-report methods indicate organized sport trends are somewhat inconsistent across countries, however most studies reported an increase in participation. Within the limited physical education trend studies, inconsistent trends were noted. There have been consistent declines in active transport, particularly cycling. Few studies have investigated trends in physical activity and sedentary behaviour during school play periods, highlighting a need for further research.
  
  
  CONCLUSIONS
  Mixed results and inconsistent magnitudes of change were identified when exploring trends in different contexts of physical activity for children and adolescents over the last few decades. Taken overall, there is little evidence for a decrease in children's and adolescents' physical activity, although consistent declines in active transport highlight this context as a suitable intervention target.
authors.affiliation: School of Health Sciences, University of South Australia, Australia. Electronic address: veritymbooth@gmail.com.
authors.forename: Verity M
authors.initials: VM
authors.lastname: Booth
authors.affiliation: School of Health Sciences, University of South Australia, Australia.
authors.forename: Alex V
authors.initials: AV
authors.lastname: Rowlands
authors.affiliation: School of Health Sciences, University of South Australia, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Dollman
mesh_terms: D000293:Adolescent; D001642:Bicycling / Q000639:trends; D002648:Child; D006801:Humans; D009043:Motor Activity; D010806:Physical Education and Training / Q000639:trends*; D010988:Play and Playthings; D012574:Schools; D057566:Self Report; D013177:Sports / Q000639:trends*; D013997:Time Factors; D014186:Transportation; D016138:Walking / Q000639:trends
keywords: Active transport; Child; Physical activity; Physical education; Sport; Trends