title: Changes in occupational class differences in leisure-time physical activity: a follow-up study.
abstract: BACKGROUND
  Physical activity is known to have health benefits across population groups. However, less is known about changes over time in socioeconomic differences in leisure-time physical activity and the reasons for the changes. We hypothesised that class differences in leisure-time physical activity would widen over time due to declining physical activity among the lower occupational classes. We examined whether occupational class differences in leisure-time physical activity change over time in a cohort of Finnish middle-aged women and men. We also examined whether a set of selected covariates could account for the observed changes.
  
  
  METHODS
  The data were derived from the Helsinki Health Study cohort mail surveys; the respondents were 40-60-year-old employees of the City of Helsinki at baseline in 2000-2002 (n = 8960, response rate 67%). Follow-up questionnaires were sent to the baseline respondents in 2007 (n = 7332, response rate 83%). The outcome measure was leisure-time physical activity, including commuting, converted to metabolic equivalent tasks (MET). Socioeconomic position was measured by occupational class (professionals, semi-professionals, routine non-manual employees and manual workers). The covariates included baseline age, marital status, limiting long-lasting illness, common mental disorders, job strain, physical and mental health functioning, smoking, body mass index, and employment status at follow-up. Firstly the analyses focused on changes over time in age adjusted prevalence of leisure-time physical activity. Secondly, logistic regression analysis was used to adjust for covariates of changes in occupational class differences in leisure-time physical activity.
  
  
  RESULTS
  At baseline there were no occupational class differences in leisure-time physical activity. Over the follow-up leisure-time physical activity increased among those in the higher classes and decreased among manual workers, suggesting the emergence of occupational class differences at follow-up. Women in routine non-manual and manual classes and men in the manual class tended to be more often physically inactive in their leisure-time (<14 MET hours/week) and to be less often active (>30 MET hours/week) than those in the top two classes. Adjustment for the covariates did not substantially affect the observed occupational class differences in leisure-time physical activity at follow-up.
  
  
  CONCLUSIONS
  Occupational class differences in leisure-time physical activity emerged over the follow-up period among both women and men. Leisure-time physical activity needs to be promoted among ageing employees, especially among manual workers.
authors.affiliation: Hjelt Institute, Department of Public Health, University of Helsinki, Helsinki, Finland. tina.seiluri@helsinki.fi
authors.forename: Tina
authors.initials: T
authors.lastname: Seiluri
authors.forename: Jouni
authors.initials: J
authors.lastname: Lahti
authors.forename: Ossi
authors.initials: O
authors.lastname: Rahkonen
authors.forename: Eero
authors.initials: E
authors.lastname: Lahelma
authors.forename: Tea
authors.initials: T
authors.lastname: Lallukka
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003625:Data Collection; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D015438:Health Behavior; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009790:Occupations; D012923:Social Class; D011795:Surveys and Questionnaires; D014186:Transportation