Abstract P072: Elevated Coronary Artery Calcification In Highly Active Men: Role Of Exercise Intensity Versus Duration

Abstract

Introduction: While living a physically active lifestyle is associated with many health benefits, recent evidence suggests that high volume physical activity (PA) may contribute to coronary artery calcification (CAC). Whether exercise intensity or duration contributes more to CAC elevation is unknown. Hypothesis: Higher PA intensity, but not duration, predicts elevated CAC. Methods: We studied 25,801 apparently healthy men who completed a self-report PA questionnaire and underwent EBT or MDCT scans as part of a preventive physical examination. Participants were categorized into two CAC groups (≥100 or <100 Agatston units (AU)) and three PA groups (≥3000, 1500 – 2999, and <1500 MET-minutes/week (MET-min/wk)). An exploratory classification tree model identified maximum intensity of activity as the second most important predictor of CAC≥100 AU after age. As such, maximal intensity of activity ≥8 METs was entered as a predictor in subsequent logistic regression models that were adjusted for age, current smoking status, body mass index, glucose, total cholesterol, and systolic blood pressure. We also included categories of PA duration ≥5 or <5 hours/week, the current PA Guidelines recommendation for increased performance. Results: The mean age was 52 years, and 6,075 men had CAC≥100 AU. Regardless of CAC category, the ≥3000 MET-min/wk group had more favorable glucose and lipid profiles compared to the <1500 group. The average PA volume reported in the most highly active group (≥3000 MET-min/wk) was 4626 MET-min/wk with all participants reporting ≥5 hours of PA/week. In the fully adjusted model, maximum exercise intensity ≥8 METs was associated with lower risk of CAC≥100 AU (Relative risk (RR): 0.93, 95% Confidence interval (CI): 0.88 – 0.98, p = 0.004), while total duration of ≥5 hours/week trended in the opposite direction yet without significance (RR: 1.07, CI 95%: 0.98 – 1.17, p = 0.14). Prevalence of CAC≥100 AU was highest among those engaging only in activities <8 METs and for a total duration ≥5 hours/week. Conversely, the lowest prevalence of CAC≥100 AU was found in the higher intensity, lower duration group (≥8 METs, <5 hours/week). Jointly, maximum intensity ≥8 METs was associated with a lower risk of CAC≥100 AU (RR: 0.92, CI 95%: 0.88 – 0.97, p =0.003) only among those with a total duration <5 hours/week. Conclusions: Exercise intensity ≥8 METs was associated with a lower likelihood of men patients presenting with clinically significant CAC while exercise duration of ≥5 hours/week trended in the opposite direction. These novel findings should be considered by clinicians when counseling highly active men with elevated CAC on their exercise prescriptions.