title: Objectively assessed physical activity, sedentary time, and coronary artery calcification in healthy older adults.
abstract: OBJECTIVE
  Physical activity is related to lower risk of cardiovascular disease, but data relating to coronary lesions have been conflicting. These inconsistencies may in part be due to unreliable assessment of physical activity and limitations imposed by self-reported data. The purpose of this study was to determine the relationship between objectively measured physical activity and coronary artery calcium (CAC).
  
  
  RESULTS
  Participants were 443 healthy men and women (mean age=66±6 years), without history or objective signs of coronary heart disease, drawn from the Whitehall II epidemiological cohort. Physical activity was objectively measured using accelerometers worn during waking hours for 7 consecutive days (average daily wear time=889±68 minutes/day). CAC was measured in each participant using electron beam computed tomography and was quantified according to the Agatston scoring system. On average, 54.4% of the sample recorded at least 30 minutes/day of moderate to vigorous physical activity (MVPA). There was no association between MVPA and presence of detectable CAC. For the participants with detectable CAC (n=283) a weak inverse relationship between MVPA (minutes/day) and log Agatston score was observed (B=-0.008, 95% CI: -0.16 to 0.00, P=0.05), although the association was no longer present after adjustments for age, sex, and conventional risk factors. No associations were seen for light activity or sedentary time.
  
  
  CONCLUSIONS
  Our results confirm no association between objectively assessed physical activity and CAC. Because CAC measures cannot identify more vulnerable lesions, additional studies are required to examine whether physical activity can promote plaque stability.
authors.affiliation: Department of Epidemiology and Public Health, 1-19 Torrington Pl, University College London, London, WC1E 6BT, United Kingdom. m.hamer@ucl.ac.uk
authors.forename: Mark
authors.initials: M
authors.lastname: Hamer
authors.forename: Shreenidhi M
authors.initials: SM
authors.lastname: Venuraju
authors.forename: Avijit
authors.initials: A
authors.lastname: Lahiri
authors.forename: Amanda
authors.initials: A
authors.lastname: Rossi
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
mesh_terms: D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D015331:Cohort Studies; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D057185:Sedentary Behavior; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium