title: Friendship Network Characteristics Are Associated with Physical Activity and Sedentary Behavior in Early Adolescence.
abstract: BACKGROUND
  There is limited understanding of the association between peer social networks and physical activity (PA), sedentary and screen-related behaviors. This study reports on associations between personal network characteristics and these important health behaviors for early adolescents.
  
  
  METHODS
  Participants were 310 students, aged 11-13 years, from fifteen randomly selected Victorian primary schools (43% response rate). PA and sedentary behaviors were collected via accelerometer and self-report questionnaire, and anthropometric measures via trained researchers. Participants nominated up to fifteen friends, and described the frequency of interaction and perceived activity intensity of these friends. Personal network predictors were examined using regression modelling for PA and sedentary/screen behavior.
  
  
  RESULTS
  Perceived activity levels of friends, and friendships with very frequent interaction were associated with outside-of-school PA and/or sedentary/screen time. Differences according to sex were also observed in the association between network characteristics and PA and sedentary time. A higher number of friends and greater proportion of same sex friends were associated with boys engaging in more moderate-to-vigorous PA outside of school hours. PA intensity during school-day breaks was positively associated with having a greater proportion of friends who played sports for girls, and a greater proportion of male friends for boys.
  
  
  CONCLUSIONS
  Friendship network characteristics are associated with PA and sedentary/screen time in late childhood/early adolescence, and these associations differ by sex. The positive influence of very active peers may be a promising avenue to strengthen traditional interventions for the promotion of PA and reduction in screen time.
authors.affiliation: WHO Collaborating Centre for Obesity Prevention, Deakin University, Geelong, Australia.|School of Health and Social Development, Deakin University, Burwood, Australia.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Marks
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Kayla
authors.initials: K
authors.lastname: de la Haye
authors.affiliation: School of Health and Social Development, Deakin University, Burwood, Australia.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Barnett
authors.affiliation: WHO Collaborating Centre for Obesity Prevention, Deakin University, Geelong, Australia.|School of Health and Social Development, Deakin University, Burwood, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Allender
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D000294:Adolescent Behavior; D000886:Anthropometry; D001315:Australia; D002648:Child; D003201:Computers / Q000706:statistics & numerical data; D015444:Exercise / Q000502:physiology*; D005260:Female; D033062:Friends; D015438:Health Behavior; D006801:Humans; D007398:Interpersonal Relations; D007899:Leisure Activities; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000453:epidemiology; D010379:Peer Group; D012574:Schools; D057185:Sedentary Behavior; D057566:Self Report; D012944:Social Support; D013177:Sports; D013334:Students; D011795:Surveys and Questionnaires