title: Physical activity in middle-aged adults reduces risks of functional impairment independent of its effect on weight.
abstract: OBJECTIVE
  To assess the association between physical activity and subsequent physical functioning in middle-aged adults across a range of body mass index (BMI) categories.
  
  
  METHODS
  Prospective nationally representative cohort studies.
  
  
  METHODS
  The United States and England.
  
  
  METHODS
  Eight thousand seven hundred two individuals in the United States and 1,507 in England aged 50 to 69 and free of impairment at baseline, followed up for 6 years.
  
  
  METHODS
  Self-reported and measured BMI and self-reported level of physical activity. Outcome measures were score on a physical performance battery and self-reported mobility impairment.
  
  
  RESULTS
  In both studies, being overweight and being obese were associated with greater risk of impairment (than being of recommended weight). In all weight categories and both countries, higher levels of physical activity were associated with lower risks of mobility impairment. For example, U.S. respondents of recommended weight (BMI 20-25) who were active on 3 or more days per week had a relative risk (RR) of incident mobility difficulties, compared with those who were less active, of 0.56 (95% confidence interval (CI)=0.40-0.78); for those who were obese (BMI >/=30) the corresponding RR was 0.59 (95% CI=0.45-0.76).
  
  
  CONCLUSIONS
  Excess bodyweight is a risk factor for impaired physical function in middle-aged and older people. Physical activity is protective of impaired physical functioning in this age group in subjects with recommended weight, overweight, and obesity. Older adults should be encouraged to engage in appropriate levels of physical activity irrespective of their weight.
authors.affiliation: Epidemiology and Public Health Group, Peninsula Medical School, Exeter, United Kingdom. iain.lang@pms.ac.uk
authors.forename: Iain A
authors.initials: IA
authors.lastname: Lang
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.forename: David
authors.initials: D
authors.lastname: Melzer
mesh_terms: D000368:Aged; D015992:Body Mass Index; D001835:Body Weight; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D004739:England; D015444:Exercise; D005260:Female; D015577:Geriatric Assessment; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009765:Obesity / Q000150:complications / Q000628:therapy; D050177:Overweight; D010809:Physical Fitness; D012307:Risk Factors; D014481:United States