title: Physical activity, falls, and fractures among older adults: a review of the epidemiologic evidence.
abstract: OBJECTIVE
  Assess the relationship between physical activity and risk for falls and osteoporotic fractures among older adults.
  
  
  METHODS
  Review and synthesis of published literature.
  
  
  METHODS
  We searched the literature using MEDLINE, Current Contents, and the bibliographies of articles identified. We included randomized controlled trials (RCT) of the effects of physical activity on the incidence of falls and case-control and prospective cohort studies of the association of physical activity with osteoporotic fracture risk. We also summarized mechanisms whereby physical activity may influence risk for falls and fractures.
  
  
  RESULTS
  Observational epidemiologic studies and randomized clinical trials evaluating the effectiveness of physical activity programs to prevent falls have been inconclusive. However, many studies have lacked adequate statistical power, and recent trials suggest that exercise, particularly involving balance and lower extremity strength training, may reduce risk of falling. There is consistent evidence from prospective and case-control studies that physical activity is associated with a 20-40% reduced risk of hip fracture relative to sedentary individuals. The few studies that have examined the association between physical activity and risk of other common osteoporotic fractures, such as vertebral and wrist fractures, have not found physical activity to be protective.
  
  
  CONCLUSIONS
  Epidemiologic studies suggest that higher levels of leisure time physical activity prevent hip fractures and RCTs suggest certain exercise programs may reduce risk of falls. Future research needs to evaluate the types and quantity of physical activity needed for optimal protection from falls and identify which populations will benefit most from exercise.
authors.affiliation: Division of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
authors.forename: E W
authors.initials: EW
authors.lastname: Gregg
authors.forename: M A
authors.initials: MA
authors.lastname: Pereira
authors.forename: C J
authors.initials: CJ
authors.lastname: Caspersen
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control* / Q000706:statistics & numerical data*; D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015986:Confounding Factors, Epidemiologic; D015444:Exercise; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors