title: The role of perceived barriers and objectively measured physical activity in adults aged 65-100.
abstract: OBJECTIVE
  to test the predictive utility of perceived barriers to objectively measured physical activity levels in a stratified sample of older adults when accounting for social-cognitive determinants proposed by the Theory of Planned Behaviour (TPB), and economic and demographic factors.
  
  
  METHODS
  data were analysed from the Physical Activity Cohort Scotland survey, a representative and stratified (65-80 and 80+ years; deprived and affluent) sample of 584 community-dwelling older people, resident in Tayside, Scotland. Physical activity was measured objectively by accelerometry.
  
  
  RESULTS
  perceived barriers clustered around the areas of poor health, lack of interest, lack of safety and lack of access. Perceived poor health and lack of interest, but not lack of access or concerns about personal safety, predicted physical activity after controlling for demographic, economic and TPB variables.
  
  
  CONCLUSIONS
  perceived person-related barriers (poor health and lack of interest) seem to be more strongly associated with physical activity levels than perceived environmental barriers (safety and access) in a large sample of older adults. Perceived barriers are modifiable and may be a target for future interventions.
authors.affiliation: Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Gellert
authors.affiliation: Section of Ageing and Health, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: Miles D
authors.initials: MD
authors.lastname: Witham
authors.affiliation: Epidemiology and Public Health, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: Iain K
authors.initials: IK
authors.lastname: Crombie
authors.affiliation: Epidemiology and Public Health, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Donnan
authors.affiliation: Department of Medicine, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: Marion E T
authors.initials: ME
authors.lastname: McMurdo
authors.affiliation: Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Falko F
authors.initials: FF
authors.lastname: Sniehotta
mesh_terms: D061725:Accelerometry; D000368:Aged / Q000523:psychology / Q000706:statistics & numerical data; D000369:Aged, 80 and over; D004779:Environment Design; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D009043:Motor Activity; D012449:Safety; D012606:Scotland / Q000453:epidemiology
keywords: older people; perceived barriers; physical activity; theory of planned behaviour