title: Do intrapersonal factors mediate the association of social support with physical activity in young women living in socioeconomically disadvantaged neighbourhoods? A longitudinal mediation analysis.
abstract: BACKGROUND
  Levels of physical activity (PA) decrease when transitioning from adolescence into young adulthood. Evidence suggests that social support and intrapersonal factors (self-efficacy, outcome expectations, PA enjoyment) are associated with PA. The aim of the present study was to explore whether cross-sectional and longitudinal associations of social support from family and friends with leisure-time PA (LTPA) among young women living in disadvantaged areas were mediated by intrapersonal factors (PA enjoyment, outcome expectations, self-efficacy).
  
  
  METHODS
  Survey data were collected from 18-30 year-old women living in disadvantaged suburbs of Victoria, Australia as part of the READI study in 2007-2008 (T0, N = 1197), with follow-up data collected in 2010-2011 (T1, N = 357) and 2012-2013 (T2, N = 271). A series of single-mediator models were tested using baseline (T0) and longitudinal data from all three time points with residual change scores for changes between measurements.
  
  
  RESULTS
  Cross-sectional analyses showed that social support was associated with LTPA both directly and indirectly, mediated by intrapersonal factors. Each intrapersonal factor explained between 5.9-37.5% of the associations. None of the intrapersonal factors were significant mediators in the longitudinal analyses.
  
  
  CONCLUSIONS
  Results from the cross-sectional analyses suggest that the associations of social support from family and from friends with LTPA are mediated by intrapersonal factors (PA enjoyment, outcome expectations and self-efficacy). However, longitudinal analyses did not confirm these findings.
authors.affiliation: Department of Epidemiology & Biostatistics and the EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Anouk
authors.identifier: http://orcid.org/0000-0002-1274-968X
authors.initials: A
authors.lastname: Middelweerd
authors.affiliation: Department of Epidemiology & Biostatistics and the EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Saskia J
authors.initials: SJ
authors.lastname: Te Velde
authors.affiliation: Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong Victoria, Australia.
authors.forename: Gavin
authors.initials: G
authors.lastname: Abbott
authors.affiliation: Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong Victoria, Australia.
authors.forename: Anna
authors.initials: A
authors.lastname: Timperio
authors.affiliation: Amsterdam School of Communication Research, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Johannes
authors.initials: J
authors.lastname: Brug
authors.affiliation: Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong Victoria, Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Ball
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008137:Longitudinal Studies; D012944:Social Support; D012959:Socioeconomic Factors; D014739:Victoria; D055815:Young Adult