title: Concordance of physical activity trajectories among middle-aged and older married couples: impact of diseases and functional difficulties.
abstract: OBJECTIVE
  This study examined spousal concordance of physical activity trajectories among middle-aged and older married couples and the influences of recent diseases and functional difficulties on individuals' trajectories and those of their spouses'.
  
  
  METHODS
  Participants included 5,074 married couples aged 50 or older in the Health and Retirement Study in 2004-2010. Participants were categorized into 4 physical activity trajectories (i.e., stable active, adopters, relapsers, and stable sedentary) using confirmatory latent class growth analysis. Individuals' trajectory memberships were predicted by their spouses' memberships, together with recent diseases and functional difficulties of both couple members.
  
  
  RESULTS
  In the main, corresponding husbands' trajectories predicted wives' trajectories and vice versa. More functional difficulties predicted higher likelihoods of unfavorable trajectories among individuals but not of their spouses'. Among wives, more recent diseases predicted slightly more physical activity in subsequent data waves but not trajectory memberships.
  
  
  CONCLUSIONS
  Results supported spousal concordance in physical activity trajectories. The negative impact of functional difficulties was considerably contained within individuals. Increases in physical activity after acquiring diseases among wives were small and short lived. More research is needed to understand the underlying processes, which can be used to improve the design of future physical activity interventions directed toward women, men, and couples.
authors.affiliation: Correspondence should be addressed to Kin-Kit Li, Y7405 Academic 1, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China. ben.li@cityu.edu.hk
authors.forename: Kin-Kit
authors.initials: KK
authors.lastname: Li
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Cardinal
authors.forename: Alan C
authors.initials: AC
authors.lastname: Acock
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D004522:Educational Status; D005260:Female; D006304:Health Status; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D007407:Interviews as Topic; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D012737:Sex Factors; D018454:Spouses / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology
keywords: Health promotion; Longitudinal methods; Physical activity.