Lifelong Exercise Volume and Atherosclerosis in Athletes
Is there a relationship between lifelong exercise volume (duration and intensity) and coronary artery calcium (CAC) and plaque characteristics?
Middle-aged men engaged in competitive or recreational leisure sports underwent a noncontrast and contrast-enhanced computed tomography scan to assess coronary artery calcification (CAC) and plaque characteristics. Participants reported lifelong exercise history patterns. Exercise volumes were multiplied by metabolic equivalent of task (MET) scores to calculate MET-minutes per week. Participants’ activity was categorized as <1000, 1000-2000, or >2000 MET-min/wk.
A total of 284 men (age, 55 ± 7 years) were included. CAC was present in 150 of 284 participants (53%) with a median CAC score of 35.8 (interquartile range [IQR], 9.3-145.8). Athletes with a lifelong exercise volume >2000 MET-min/wk (n = 75) had a significantly higher CAC score (9.4 [IQR, 0-60.9] vs. 0 [IQR, 0-43.5], p = 0.02) and prevalence of CAC (68%, adjusted odds ratio [ORadj] = 3.2; 95% confidence interval [CI], 1.6-6.6) and plaque (77%, ORadj = 3.3, 95% CI, 1.6-7.1) compared with <1000 MET-min/wk (n = 88; 43% and 56%, respectively). Very vigorous intensity exercise (≥9 MET) was associated with CAC (ORadj = 1.47; 95% CI, 1.14-1.91) and plaque (ORadj = 1.56; 95% CI, 1.17-2.08). Among participants with CAC >0, there was no difference in CAC score (p = 0.20), area (p = 0.21), density (p = 0.25), and regions of interest (p = 0.20) across exercise volume groups. Among participants with plaque, the most active group (>2000 MET-min/wk) had a lower prevalence of mixed plaques (48% vs. 69%, ORadj = 0.35; 95% CI, 0.15-0.85) and more often had only calcified plaques (38% vs. 16%, ORadj = 3.57; 95% CI, 1.28-9.97) compared with the least active group (<1000 MET-min/wk).
Participants in the >2000 MET-min/wk group had a higher prevalence of CAC and atherosclerotic plaques. The most active group, however, had a more benign composition of plaques, with fewer mixed plaques and more often only calcified plaques. The authors concluded that these observations may explain the increased longevity typical of endurance athletes despite the presence of more coronary atherosclerotic plaque in the most active participants.
Higher levels of physical activity are associated with a lower risk of cardiovascular events. However, high levels of physical exercise also can be associated with significant CAC, and debate continues regarding the dose-response relationship between exercise and cardiovascular disease outcomes. These data suggest that, despite a high prevalence of CAC among middle-aged men engaged in longer duration/more intense exercise, plaque composition was more benign. Although higher levels of coronary calcium in a general population might be associated with increased cardiovascular risk, these data (along with data from another article in the same issue [doi: 10.1161/CIRCULATIONAHA.116.026964]) suggest that the CAC versus cardiovascular risk relationship might be different among athletes.
Keywords: Atherosclerosis, Athletes, Cardiac Imaging Techniques, Cardiovascular Diseases, Coronary Artery Disease, Exercise, Ischemia, Longevity, Metabolic Equivalent, Plaque, Atherosclerotic, Primary Prevention, Risk Factors, Sports, Tomography
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