title: Physical disability in older runners: prevalence, risk factors, and progression with age.
abstract: BACKGROUND
  Concern exists that certain types of exercise, particularly vigorous activity, may increase physical disability among older individuals. We investigated the prevalence of, and risk factors for, physical disability in active older persons (runners), and examined factors influencing the progression of physical disability with age.
  
  
  METHODS
  Physical disability, measured using the Health Assessment Questionnaire Disability Index, was assessed prospectively in 454 runners, age 50 or greater, over five to seven years by annual mailed questionnaires. Baseline sociodemographic, clinical, and life-style characteristics associated with the presence of any disability over the course of the study were determined and contrasted with those in 292 older non-runners who had been similarly followed.
  
  
  RESULTS
  Two hundred twenty-two runners (49%) reported some physical disability during the study. The presence of arthritis symptoms at baseline was the most important risk factor for physical disability; older age, greater body mass index, strenuous work-related physical activity, and the use of more medications were also associated with a greater likelihood of physical disability. Among the non-runners, 224 (77%) reported some physical disability, and the presence of arthritis symptoms was also the most important risk factor for physical disability in this group. Age-related changes in physical disability differed between those with and without arthritis symptoms in both the runner and non-runner groups.
  
  
  CONCLUSIONS
  The presence of arthritis symptoms was an important risk factor for physical disability among both older runners and non-runners, and also identified subgroups of individuals with different progressions of disability with age.
authors.affiliation: Veterans Affairs Medical Center, Palo Alto, California.
authors.forename: M M
authors.initials: MM
authors.lastname: Ward
authors.forename: H B
authors.initials: HB
authors.lastname: Hubert
authors.forename: H
authors.initials: H
authors.lastname: Shi
authors.forename: D A
authors.initials: DA
authors.lastname: Bloch
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001168:Arthritis / Q000503:physiopathology; D015992:Body Mass Index; D015331:Cohort Studies; D006233:Persons with Disabilities; D018450:Disease Progression; D004358:Drug Therapy; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012420:Running / Q000502:physiology*; D012923:Social Class; D014937:Work / Q000502:physiology