title: Effect of sedentary behaviour and vigorous physical activity on segment-specific carotid wall thickness and its progression in a healthy population.
abstract: OBJECTIVE
  This study investigated whether sedentary behaviour and different activity levels have an independent association with carotid intima-media thickness (IMT) and with the 3-year IMT progression in different carotid segments.
  
  
  RESULTS
  The study population included 614 healthy men and women (mean age = 44 +/- 8 years) without carotid atherosclerosis and without increased coronary heart disease risk, who underwent B-mode carotid ultrasound and objective physical activity assessment by accelerometer (mean monitoring time = 5.7 +/- 1.5 days). Time spent in sedentary (57.6 +/- 9.1%), light (41.0 +/- 9.2%), moderate and vigorous activities was determined. Sedentary behaviour was expressed as the ratio of time spent in sedentary and light activity (sedentary/light ratio) as these two activities occupied the majority of waking time. In 495 subjects, the carotid ultrasound was repeated 3 years after the baseline examination. After adjustment for age and the established risk factors that were independent determinants of carotid wall thickness in our population, sedentary/light ratio was independently associated only with the common carotid artery (CCA) IMT. The 3-year increase in CCA IMT was significantly lower in subjects with periods of vigorous activity (7 +/- 40 microm) when compared with those with light activity only or with periods of moderate activity (22 +/- 51 and 19 +/- 46 microm, respectively, P < 0.05).
  
  
  CONCLUSIONS
  The healthy, young-to-middle age population of this study spent more than half of their waking time in sedentary activities. The proportion of time spent in sedentary activities was directly associated with baseline CCA IMT, independently of age and established atherosclerotic risk factors. In the longitudinal analysis, period of vigorous activity influenced the 3-year IMT progression in CCA.
authors.affiliation: Department of Internal Medicine, University of Pisa, Via Roma, 67, Pisa 56122, Italy. m.kozakova@in.med.unipi.it
authors.forename: Michaela
authors.initials: M
authors.lastname: Kozàkovà
authors.forename: Carlo
authors.initials: C
authors.lastname: Palombo
authors.forename: Carmela
authors.initials: C
authors.lastname: Morizzo
authors.forename: John J
authors.initials: JJ
authors.lastname: Nolan
authors.forename: Thomas
authors.initials: T
authors.lastname: Konrad
authors.forename: Beverley
authors.initials: B
authors.lastname: Balkau
mesh_terms: D000328:Adult; D001823:Body Composition; D017536:Carotid Artery, Common / Q000033:anatomy & histology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D057185:Sedentary Behavior; D017539:Tunica Intima / Q000033:anatomy & histology; D017540:Tunica Media / Q000033:anatomy & histology