Association between physical activity and carotid atherosclerosis

Abstract

Background/aim: Physical activity reduces the risk of cardiovascular disease (CVD). Atherosclerosis is an important common underlying cause of CVD. It is not clear whether the beneficial effect of physical activity on CVD is mediated through effect on atherosclerosis, and previous studies have shown diverging results. The aim of this study was to investigate the association between level of physical activity and atherosclerosis. Method and materials: We included 10,894 participants of the Tromsø Study (1994-2008) who was measured with ultrasound of the carotid artery. Atherosclerosis was assessed as intima-media thickness (IMT), plaque presence (yes/no) and total plaque area (TPA). Linear regression models were used to assess the association between physical activity and intima-media thickness and total plaque area. Logistic regression models were used to assess the association between physical activity across quartiles of IMT and categories of plaque. Results: We found a significant trend toward lower plaque prevalence and smaller TPA with increasing degree of physical activity. In age-and sex-adjusted models, the OR for plaque presence was 0.74% (95% CI 0.68-0.81) for moderate physical activity and -0.04 (95% CI -0.06 - -0.02) compared to low physical activity. Similar trends were found in age-and-sex-adjusted linear regression analyses or the association between physical activity and TPA. There was an interaction for sex between physical activity and IMT, with a significant inverse association for moderate physical activity (beta-coefficient -0.01 (95% CI -0.02 - -0.001, p=0.02)) and a borderline significance in those with high physical activity (beta-coefficient -0.01 (95% CI -0.03 – 0.000, p=0.06) in men, but not in women. Conclusion: Physical activity was significantly associated with carotid IMT in men in age-adjusted models and with plaque in age-and-sex-adjusted models. Adjustment for traditional CVD risk factors attenuated these associations. This may imply that the effect of physical activity on atherosclerosis is mediated through effecting these risk factors.