title: Association between changes in habitual physical activity and changes in bone density, muscle strength, and functional performance in elderly men and women.
abstract: OBJECTIVE
  To investigate the long-term effects of habitual physical activity on changes in musculoskeletal health, functional performance, and fracture risk in elderly men and women.
  
  
  METHODS
  Ten-year prospective population-based study.
  
  
  METHODS
  Malmö-Sjöbo Prospective Study, Sweden.
  
  
  METHODS
  Participants were 152 men and 206 women aged 50, 60, 70, and 80 who were followed for 10 years.
  
  
  METHODS
  Distal radius bone mineral density (BMD) (single photon absorptiometry), upper limb muscle (grip) strength, balance, gait velocity, occupational and leisure-time activity, and fractures (interview-administered questionnaire) were reassessed after 10 years. Annual changes for all measures were compared between participants with varying habitual physical activity histories at baseline and follow-up: inactive-inactive (n=202), active-inactive (n=47), inactive-active (n=49), and active-active (n=60). Data for men and women were pooled, because there were no sex-by-activity group interactions. To detect possible differences in fracture incidence between the varying habitual activity groups, participants were classified into two activity groups based on their activity classification at baseline and follow-up: inactive:less active versus active:more active.
  
  
  RESULTS
  The annual rate of bone loss was 0.6% per year less in individuals classified as active at both time points than in those classified as inactive at both time points (P<.01). Similar results were observed for balance, but there was no effect of varying habitual activity on changes in muscle strength or gait velocity. There were also no differences in fracture incidence between individuals categorized as active:more active and those categorized as inactive:less active during the follow-up (adjusted hazard ratio=0.90, 95% confidence interval (CI)=0.42-1.90).
  
  
  CONCLUSIONS
  This study showed that elderly men and women who maintained a habitually active lifestyle over 10 years had lower bone loss and retained better balance than those who remained habitually inactive.
authors.affiliation: Department of Medicine, University of Melbourne, Western Hospital, Footscray, Melbourne, Australia. rdaly@unimelb.edu.au
authors.forename: Robin M
authors.initials: RM
authors.lastname: Daly
authors.forename: Henrik G
authors.initials: HG
authors.lastname: Ahlborg
authors.forename: Karin
authors.initials: K
authors.lastname: Ringsberg
authors.forename: Per
authors.initials: P
authors.lastname: Gardsell
authors.forename: Ingemar
authors.initials: I
authors.lastname: Sernbo
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Karlsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D050723:Fractures, Bone / Q000453:epidemiology*; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D004856:Postural Balance; D011446:Prospective Studies