title: Factors associated with adolescents' physical inactivity in Xi'an City, China.
abstract: OBJECTIVE
  To explore the sociodemographic and environmental factors at community, school, and household levels associated with physical inactivity.
  
  
  METHODS
  In a cross-sectional study in 2004, physical activity level was assessed using a validated questionnaire in 1787 students. Physical inactivity was defined as less than 150 min.wk of moderate activity (4-6 METs) or less than 60 min.wk of vigorous activity (> 6 METs). Sociodemographic and environmental information was recorded on self-administered questionnaires. Hierarchical multiple logistic models were developed based on a conceptual framework of factors related to physical activity.
  
  
  RESULTS
  Overall, girls were twice as likely to be inactive. Adolescents aged 14 yr were 30% less likely to be inactive compared with those younger than 13 yr (95% CI: 0.5-0.9). Paternal education was inversely associated with inactivity (OR: 0.6, 95% CI: 0.4-0.9). Adolescents living in neighborhoods without sidewalks were 1.3 times more likely to be inactive (95% CI: 1.0-1.6). At the school level, lack of extracurricular exercise (OR: 1.3, 95% CI: 1.1-1.6) and fewer sports meetings (OR: 2.0, 95% CI: 1.4-2.9) were associated with physical inactivity. Difficult access to community recreational facilities (moderate OR: 1.4, 95% CI: 1.0-1.9; difficult OR: 1.7, 95% CI: 1.2-2.4) and concerns about safety in the neighborhood (OR: 2.1, 95% CI: 1.1-4.1) were associated with inactivity. There were some differences associated with physical inactivity between boys and girls.
  
  
  CONCLUSIONS
  Strategies to promote physical activity in Chinese adolescents should integrate associated factors at household, school, and community levels and address the important gender differences in factors associated with physical inactivity in youth.
authors.affiliation: Department of Public Health, School of Medicine, Xi'an Jiaotong University, Xi'an, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Dibley
authors.forename: David
authors.initials: D
authors.lastname: Sibbritt
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000367:Age Factors; D015992:Body Mass Index; D002681:China; D003430:Cross-Sectional Studies; D004522:Educational Status; D015444:Exercise; D005191:Family Characteristics; D005220:Fathers; D005260:Female; D015438:Health Behavior; D006801:Humans; D016015:Logistic Models; D008297:Male; D012111:Residence Characteristics; D012449:Safety; D012574:Schools; D012737:Sex Factors; D011795:Surveys and Questionnaires