Walking and calcified atherosclerotic plaque in the coronary arteries

Objective - Studies have reported mixed findings on the association between physical activity and subclinical atherosclerosis. We sought to examine whether walking is associated with prevalent coronary artery calcification (CAC) and aortic calcification. Approach and Results - In a cross-sectional design, we studied 2971 participants of the National Heart, Lung, and Blood Institute Family Heart Study without a history of myocardial infarction, coronary artery bypass grafting, or percutaneous transluminal angioplasty. A standardized questionnaire was used to ascertain the number of blocks walked daily to compute walking metabolic equivalent hours. CAC was measured by cardiac computed tomography. We defined prevalent CAC and aortic calcification using an Agatston score of at least 100 and used generalized estimating equations to calculate adjusted prevalence ratios. Mean age was 55 years, and 60% of participants were women. Compared with the ≤3.75-Met-h/wk group, prevalence ratios for CAC after adjusting for age, sex, race, smoking, alcohol use, total physical activity (excluding walking), and familial clustering were 0.53 (95% confidence interval, 0.35-0.79) for >3.75 to 7.5 Met-h/wk, 0.72 (95% confidence interval, 0.52-0.99) for >7.5 to 15 Met-h/wk, and 0.54 (95% confidence interval, 0.36-0.81) for >15 to 22.5 Met-h/wk, (P trend=0.01). The walking-CAC relationship remained significant for those with body mass index ≥25 (P trend=0.02) and persisted with CAC cutoffs of 300, 200, 150, and 50 but not 0. When examined as a continuous variable, a J-shaped association between walking and CAC was found. The walking-aortic calcification association was not significant. Conclusions - Our findings suggest that walking is associated with lower prevalent CAC (but not aortic calcification) in adults without known heart disease.