title: Changes over time in physical activity and psychological distress among older adults.
abstract: OBJECTIVE
  While previous research has established that regular involvement in physical activity (PA) is associated with better mental health in old age, the socio-cognitive factors that mediate the association have only been partially tested. We examined whether changes in PA are associated with changes in distress during a 6-year period, and whether this association is mediated by changes in global self-esteem, mastery, and physical health status.
  
  
  METHODS
  A residualized regression technique was used to examine changes over time in a national longitudinal survey of adults aged 65 years and older (n = 1327).
  
  
  RESULTS
  There is a significant association between change in PA and change in distress. Separately, physical health status accounted for 30% of the explained variance of the longitudinal relation between PA and distress, while global self-esteem and mastery accounted for 39%. Combined, they accounted for 50% of the explained variance of PA on distress.
  
  
  CONCLUSIONS
  These findings highlight the importance of psychosocial factors in the relation between PA and distress. Results suggest that PA interventions focused on improving mastery or self-worth, as well as physical fitness, may yield the greatest benefit in alleviating psychological distress.
authors.affiliation: Department of Family, McMaster, University, Hamilton, Ontario. cairnej@mcmaster.ca
authors.forename: John
authors.initials: J
authors.lastname: Cairney
authors.forename: Guy
authors.initials: G
authors.lastname: Faulkner
authors.forename: Scott
authors.initials: S
authors.lastname: Veldhuizen
authors.forename: Terrance J
authors.initials: TJ
authors.lastname: Wade