title: Prospective epidemiological cohort study of reduced risk for incident cataract with vigorous physical activity and cardiorespiratory fitness during a 7-year follow-up.
abstract: OBJECTIVE
  To test whether greater vigorous physical activity (kilometers per week run) and greater cardiorespiratory fitness (10-km race performance in meters per second) reduce the incidence of clinically diagnosed cataract.
  
  
  METHODS
  Prospective cohort study of self-reported clinical diagnosis of cataract in nondiabetic, nonvegetarian, and nonsmoking male (n = 29,025) and female runners (n = 11,967).
  
  
  RESULTS
  Incident cataracts were reported by 733 (2.53%) men and 179 (1.50%) women during (mean +/- SE) 7.74 +/- 0.01 and 7.42 +/- 0.02 years of follow-up, respectively. The risk for incident cataract increased with BMI, such that the risk in men > 27.5 kg/m(2) was 88% larger than in men < 20 kg/m(2). Men's cataract risk declined significantly in relation to running distance (P = 0.01), even when adjusted for BMI. Men who ran > or = 64 km/wk had 35% lower risk for cataract than those reporting < 16 km/wk (28% lower risk when adjusted for BMI). In addition, men with greater cardiorespiratory fitness were at significantly less risk for development of cataract than were the least fit men. This result was not accounted for by adjustment for running distance or BMI. Compared with the least fit men, those who ran faster than 4.75 m/s had 50% lower risk for incident cataract (43% lower when adjusted for km/wk and BMI).
  
  
  CONCLUSIONS
  These data suggest that the men's cataract risk decreased in association with lower BMI, greater physical activity, and greater cardiorespiratory fitness, the latter being statistically independent of both BMI and physical activity. The study limitations include the absence of confirmation of the clinical diagnosis and the lack of specificity of the type of cataract.
authors.affiliation: Donner Laboratory, Life Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. ptwilliams@lbl.gov
authors.forename: Paul T
authors.initials: PT
authors.lastname: Williams
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002140:California / Q000453:epidemiology; D002320:Cardiovascular Physiological Phenomena; D002386:Cataract / Q000453:epidemiology*; D015331:Cohort Studies; D016021:Epidemiologic Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012143:Respiratory Physiological Phenomena; D012306:Risk; D012307:Risk Factors; D012420:Running; D011795:Surveys and Questionnaires