title: Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013.
abstract: OBJECTIVE
  To quantify the dose-response associations between total physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events.
  
  
  METHODS
  Systematic review and Bayesian dose-response meta-analysis.
  
  
  METHODS
  PubMed and Embase from 1980 to 27 February 2016, and references from relevant systematic reviews. Data from the Study on Global AGEing and Adult Health conducted in China, Ghana, India, Mexico, Russia, and South Africa from 2007 to 2010 and the US National Health and Nutrition Examination Surveys from 1999 to 2011 were used to map domain specific physical activity (reported in included studies) to total activity.
  
  
  METHODS
  Prospective cohort studies examining the associations between physical activity (any domain) and at least one of the five diseases studied.
  
  
  RESULTS
  174 articles were identified: 35 for breast cancer, 19 for colon cancer, 55 for diabetes, 43 for ischemic heart disease, and 26 for ischemic stroke (some articles included multiple outcomes). Although higher levels of total physical activity were significantly associated with lower risk for all outcomes, major gains occurred at lower levels of activity (up to 3000-4000 metabolic equivalent (MET) minutes/week). For example, individuals with a total activity level of 600 MET minutes/week (the minimum recommended level) had a 2% lower risk of diabetes compared with those reporting no physical activity. An increase from 600 to 3600 MET minutes/week reduced the risk by an additional 19%. The same amount of increase yielded much smaller returns at higher levels of activity: an increase of total activity from 9000 to 12 000 MET minutes/week reduced the risk of diabetes by only 0.6%. Compared with insufficiently active individuals (total activity <600 MET minutes/week), the risk reduction for those in the highly active category (≥8000 MET minutes/week) was 14% (relative risk 0.863, 95% uncertainty interval 0.829 to 0.900) for breast cancer; 21% (0.789, 0.735 to 0.850) for colon cancer; 28% (0.722, 0.678 to 0.768) for diabetes; 25% (0.754, 0.704 to 0.809) for ischemic heart disease; and 26% (0.736, 0.659 to 0.811) for ischemic stroke.
  
  
  CONCLUSIONS
  People who achieve total physical activity levels several times higher than the current recommended minimum level have a significant reduction in the risk of the five diseases studied. More studies with detailed quantification of total physical activity will help to find more precise relative risk estimates for different levels of activity.
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Hmwe H
authors: HH
authors: Kyu
authors: School of Medicine, University of Washington, Seattle, WA 98105, USA.
authors: Victoria F
authors: VF
authors: Bachman
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Lily T
authors: LT
authors: Alexander
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: John Everett
authors: JE
authors: Mumford
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Ashkan
authors: A
authors: Afshin
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Kara
authors: K
authors: Estep
authors: School of Public Health, Faculty of Medicine and Biomedical Sciences, University of Queensland, Herston, QLD 4006, Australia.
authors: J Lennert
authors: JL
authors: Veerman
authors: Geisel School of Medicine, Dartmouth College, Hanover, NH 03755-1404, USA.
authors: Kristen
authors: K
authors: Delwiche
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Marissa L
authors: ML
authors: Iannarone
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Madeline L
authors: ML
authors: Moyer
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Kelly
authors: K
authors: Cercy
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Theo
authors: T
authors: Vos
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA.
authors: Christopher J L
authors: CJ
authors: Murray
authors: Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA 98121, USA forouzan@uw.edu.
authors: Mohammad H
authors: MH
authors: Forouzanfar
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000453:epidemiology*; D003920:Diabetes Mellitus / Q000453:epidemiology*; D015444:Exercise; D005869:Ghana / Q000453:epidemiology; D000071219:Global Burden of Disease; D006801:Humans; D007194:India / Q000453:epidemiology; D055686:Metabolic Equivalent; D008800:Mexico / Q000453:epidemiology; D017202:Myocardial Ischemia / Q000453:epidemiology*; D012307:Risk Factors; D012426:Russia / Q000453:epidemiology; D013019:South Africa / Q000453:epidemiology; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors