Aims: 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.
Methods and 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).
Conclusion: 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.