title: Application of stages of change model to adolescents' physical activity in relation to psychological variables.
abstract: OBJECTIVE
  This study investigated the stages of change in physical activity in relation to psychological variables: self-efficacy, physical self-concept and barriers to physical activity, as well as gender. Furthermore, cluster profiles were created based on psychological variables to be compared with stages of change groups.
  
  
  METHODS
  Data were obtained from a representative sample of adolescents (N.=1618, 14.46±1.28 years) from Aragon region (Spain). The different strata were selected according to the geographical region, environment, type of school, age and gender
  
  
  RESULTS
  Males (75.5%) and very active adolescents (96.9% participant boys and 93.5% participants girls) were more prevalent in the action and maintenance groups. We found significant differences in psychosocial variables by stages of change and gender, showing higher scores in active groups for physical self-concept (effects of gender and stages of change: F(1, 1618)=313.82 P<0.001, η²=0.230) and self-efficacy (F(1, 1618)=324.34 P<0.001, η²=0.236), and lower scores in passive groups for intrapersonal (F(1, 1618)=179.73 P<0.001, η²=0.146) and extrapersonal barriers (F(1, 1618)=189.42 P<0.001, η²=0.153). Psychological cluster profiles created with these variables showed significant relationships with stages of change groups (χ²(1)=162,76, P<0.001; Pearson R=0.359 P<0.001).
  
  
  CONCLUSIONS
  The findings of the research suggest the importance of the study, showing strong determinants of PA, physical self-concept, self-efficacy and perceived barriers, in relation to the intention to change behaviour, not only stage of change model variables. Furthermore, the study can be relevant to designing more effective health promotion programmes in the adolescent population.
authors.affiliation: Faculty of Social Sciences and Humanities, University of Zaragoza, Teruel, Spain - aabarca@unizar.es.
authors.forename: A
authors.initials: A
authors.lastname: Abarca-Sos
authors.forename: J E
authors.initials: JE
authors.lastname: Bois
authors.forename: E
authors.initials: E
authors.lastname: Generelo
authors.forename: J A
authors.initials: JA
authors.lastname: Julián
authors.forename: J
authors.initials: J
authors.lastname: Zaragoza
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D002648:Child; D015444:Exercise / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D015995:Prevalence; D012649:Self Concept; D020377:Self Efficacy