title: Relationship of sedentary behavior and physical activity to incident cardiovascular disease: results from the Women's Health Initiative.
abstract: OBJECTIVE
  The aim of this study was to examine the independent and joint associations of sitting time and physical activity with risk of incident cardiovascular disease (CVD).
  
  
  BACKGROUND
  Sedentary behavior is recognized as a distinct construct beyond lack of leisure-time physical activity, but limited data exist on the interrelationship between these 2 components of energy balance.
  
  
  METHODS
  Participants in the prospective Women's Health Initiative Observational Study (n = 71,018), 50 to 79 years of age and free of CVD at baseline (1993 to 1998), provided information on sedentary behavior, defined as hours of sitting/day, and usual physical activity at baseline and during follow-up through September 2010. First CVD (coronary heart disease or stroke) events were centrally adjudicated.
  
  
  RESULTS
  Sitting ≥10 h/day compared with ≤5 h/day was associated with increased CVD risk (hazard ratio: 1.18, 95% confidence interval: 1.09 to 1.29) in multivariable models including physical activity. Low physical activity was also associated with higher CVD risk (p for trend < 0.001). When women were cross-classified by sitting time and physical activity (p for interaction = 0.94), CVD risk was highest in inactive women (≤1.7 metabolic equivalent task-h/week) who also reported ≥10 h/day of sitting. Results were similar for coronary heart disease and stroke when examined separately. Associations between prolonged sitting and risk of CVD were stronger in overweight versus normal weight women and women 70 years of age and older compared with younger women.
  
  
  CONCLUSIONS
  Prolonged sitting time was associated with increased CVD risk, independent of leisure-time physical activity, in postmenopausal women without a history of CVD. A combination of low physical activity and prolonged sitting augments CVD risk.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115, USA. akaye@hsph.harvard.edu
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Chomistek
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Marcia L
authors.initials: ML
authors.lastname: Stefanick
authors.forename: Bing
authors.initials: B
authors.lastname: Lu
authors.forename: Megan
authors.initials: M
authors.lastname: Sands-Lincoln
authors.forename: Scott B
authors.initials: SB
authors.lastname: Going
authors.forename: Lorena
authors.initials: L
authors.lastname: Garcia
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Allison
authors.forename: Stacy T
authors.initials: ST
authors.lastname: Sims
authors.forename: Michael J
authors.initials: MJ
authors.lastname: LaMonte
authors.forename: Karen C
authors.initials: KC
authors.lastname: Johnson
authors.forename: Charles B
authors.initials: CB
authors.lastname: Eaton
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D015999:Multivariate Analysis; D050177:Overweight / Q000453:epidemiology; D017698:Postmenopause / Q000502:physiology; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D057185:Sedentary Behavior; D015996:Survival Rate; D013997:Time Factors; D014481:United States; D016387:Women's Health