title: Factors predicting changes in physical activity through adolescence: the Young-HUNT Study, Norway.
abstract: OBJECTIVE
  The purpose of this prospective population-based study was to analyze predictors of changes in physical activity (PA) levels from early to late adolescence.
  
  
  METHODS
  Data presented are from 2,348 adolescents and their parents who participated in the Nord-Trøndelag Health study (HUNT 2, 1995-1997) and at follow-up in Young-HUNT 2, 2000-2001 Participants completed a self-reported questionnaire and participated in a clinical examination that included measurements of height and weight.
  
  
  RESULTS
  Four patterns of PA emerged in the study: active or inactive at both time points (active maintainers, 13%; inactive maintainers, 59%), inactive and became active (adopters, 12%), active and became inactive (relapsers, 16%). Being overweight, dissatisfied with life, and not actively participating in sports at baseline were significant predictors of change regarding PA among boys at follow-up. For girls, smoking, drinking, low maternal education, and physical inactivity predicted relapsers and inactive maintainers. Higher levels of education and more physically active parents at baseline seemed to protect against decreased PA during follow-up for both genders.
  
  
  CONCLUSIONS
  Predictors of change in, or maintaining PA status during adolescence differed by gender. These results suggest that PA-promoting interventions should be tailored by gender and focus on encouraging activity for inactive adolescents and maintenance of PA in those already active.
authors.affiliation: Faculty of Health Science, Nord-Trøndelag University College, Levanger, Norway. vegar.rangul@hint.no
authors.forename: Vegar
authors.initials: V
authors.lastname: Rangul
authors.forename: Turid Lingaas
authors.initials: TL
authors.lastname: Holmen
authors.forename: Adrian
authors.initials: A
authors.lastname: Bauman
authors.forename: Grete H
authors.initials: GH
authors.lastname: Bratberg
authors.forename: Nanna
authors.initials: N
authors.lastname: Kurtze
authors.forename: Kristian
authors.initials: K
authors.lastname: Midthjell
mesh_terms: D000293:Adolescent; D001835:Body Weight; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007899:Leisure Activities; D008019:Life Style; D008297:Male; D009043:Motor Activity; D009664:Norway; D010809:Physical Fitness; D011159:Population Surveillance; D011446:Prospective Studies; D017678:Sex Distribution; D012737:Sex Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D055815:Young Adult