title: The worldwide prevalence of insufficient physical activity in adolescents; a systematic review.
abstract: OBJECTIVE
  To perform a systematic review of crosssectional studies on the prevalence of insufficient physical activity (IPA) based on a WHO-defined cutoff point (< 60 min/d of moderate and vigorous physical activity).
  
  
  METHODS
  The search was carried out using online databases (BioMed Central, CINAHL, EMBASE, ERIC, PsycInfo, PubMed MEDLINE, SCOPUS, SPORTDiscus), and included articles published from the beginning of the databases until February18th, 2012, as well as references cited by the retrieved articles and information provided by the authors. Only original articles using questionnaires in the diagnosis were considered.
  
  
  RESULTS
  Of 2,384 papers initially retrieved, fifteen studies met the inclusion criteria, of which seven were conducted in Brazil. The prevalence of IPA varied from 18.7% to 90.6%, with a median of 79.7%. In all surveys, the prevalence was higher among girls than boys and the developing countries have higher prevalence.
  
  
  CONCLUSIONS
  We concluded that the prevalence of IPA is high among adolescents and that the definition adopted in this study is rarely used in the literature. These results suggesting that is necessary the development of interventions for increasing physical activity levels among adolescents.
authors.affiliation: Instituto do Coração do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Augusto César Ferreira
authors.initials: AC
authors.lastname: de Moraes
authors.forename: Paulo Henrique
authors.initials: PH
authors.lastname: Guerra
authors.forename: Paulo Rossi
authors.initials: PR
authors.lastname: Menezes
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D015995:Prevalence; D057185:Sedentary Behavior