title: Walking and running are associated with similar reductions in cataract risk.
abstract: OBJECTIVE
  Habitual running has been associated with reduced risk of cataract development in one prospective study. The purposes of the current analyses were to provide further evidence of this potentially important benefit of vigorous exercise and to test whether moderate exercise (e.g., walking) provides as significant and equivalent reduction in cataract risk as vigorous exercise (e.g., running).
  
  
  METHODS
  Cox proportional hazard analyses of self-reported, physician-diagnosed incident cataracts versus baseline energy expenditure (METs) in 32,610 runners and 14,917 walkers during a 6.2-yr follow-up. Results are reported as hazard ratios (HR), percent risk reductions (100 (HR - 1)), and 95% confidence intervals (95% CI).
  
  
  RESULTS
  Runners and walkers reported 733 and 1074 incident cataracts during follow-up, respectively. When adjusted for sex, race, age, education, smoking, and intakes of meat, fruit, and alcohol, lower cataract risk was significantly associated with both running (HR = 0.960 per MET·h·d, 95% CI 0.935-0.986) and walking (HR = 0.918 per MET·h·d, 95% CI = 0.881-0.956), with no significant difference in the risk reduction per MET-hours per day between running and walking or between men and women. Compared with running or walking at or below guideline levels (≤1.8 MET·h·d), incident cataract risk was significantly lower for running or walking 1.8-3.6 (16.4% lower, 95% CI = 6.4%-25.3%), 3.6-5.4 (19.0% lower, 95% CI = 5.6%-30.4%), 5.4-7.2 (26.2% lower, 95% CI = 11.2%-38.7%), 7.2-9.0 (34.1% lower, 95% CI = 10.0%-51.2%), and ≥9 MET·h·d (41.6% lower, 95% CI = 19.8%-57.4%).
  
  
  CONCLUSIONS
  Moderate (walking) and vigorous (running) exercise were both significantly associated with lower cataract risk and their effects similar. Cataract risk appears to decrease linearly with increasing exercise energy expenditure through 9 MET·h·d.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. ptwilliams@lbl.gov
authors.forename: Paul T
authors.initials: PT
authors.lastname: Williams
mesh_terms: D000328:Adult; D000368:Aged; D002386:Cataract / Q000453:epidemiology / Q000517:prevention & control*; D004734:Energy Metabolism; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness; D016016:Proportional Hazards Models; D012306:Risk; D012420:Running; D057566:Self Report; D016138:Walking