Exercise and physical activity reduce the risk of cardiovascular disease (CVD). It has been observed that an active person has a 30-40% lower risk of CVD. However, previous cross-sectional studies have failed to determine whether exercise has a significant effect on the acceleration of coronary atherosclerosis and plaque morphology. A recent article in the journal Circulation focused on examining the relationship between exercise volume and intensity and progression of coronary atherosclerosis in middle-aged and elderly male athletes.
Study: Exercise volume versus intensity and progression of coronary atherosclerosis in middle-aged and elderly athletes: findings from the MARC-2 study. Image credit: Sciencepics / ShutterstockStudy: Exercise volume versus intensity and progression of coronary atherosclerosis in middle-aged and older athletes: findings from the MARC-2 study. Image credit: Sciencepics/Shutterstock
Background
Coronary artery calcification (CAC) is a biomarker for coronary atherosclerotic plaque burden and future risk of CVD events. This biomarker can be measured using a computed tomography (CT) imaging technique. In addition, a more detailed study of coronary plaque morphology can be performed using coronary CT angiography (CCTA).
Typically, athletes have a CAC score ≥100 Agatstone units, which correlates with lifelong training volume and exercise intensity. In active athletes, the morphology of atherosclerotic plaque is more calcified or partially calcified. Recent studies have shown that amateur athletes have higher coronary atherosclerosis compared to less active healthy individuals.
About the study
The present study used CAC and CCTA scoring to evaluate the relationship between exercise training characteristics and coronary atherosclerosis in middle-aged and elderly male athletes. This study hypothesized that greater volume and intensity of exercise is associated with a higher incidence of coronary atherosclerosis.
The current study is known as MARC-2 (Measurement of Risk of Cardiovascular Events in Athletes 2), which is a follow-up to the MARC-1 (Measurement of Risk of Cardiovascular Events in Athletes 1) study.
The MARC-2 study recruited asymptomatic middle-aged and older men over 45 years of age and showed no abnormalities in their exercise medicine assessment between May 2019 and February 2020. People who underwent percutaneous coronary intervention during follow-up were excluded from the study.
Relevant information about the exercise characteristics of the participants was obtained through a validated questionnaire. This questionnaire focused on collecting information on the type of exercise, frequency, duration for each exercise (in years), duration of a training session, and performance level, i.e. recreation vs. Competitive, from the study group.
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A metabolic equivalent of work (MET) was assigned for all reported sports based on the physical activity pool. The present study used training volume, in terms of MET hours per week, during the study period.
Study findings
The present study included a total of 291 men. Based on the eligibility criteria, 287 men were finally included in the MARC-2 CAC analysis and 284 men were included in the plaque analysis. It was observed that the mean follow-up between CT scans was 6.3 years. In addition, blood pressure levels and the use of antihypertensive drugs and statins were significantly increased during the follow-up period. However, the participants' cholesterol levels remained stable during the follow-up period. Six participants had quit smoking.
Exercise intensity, but not volume, was associated with progression of coronary atherosclerosis. The effect of vigorous exercise on the progression of CAC was less effective. However, very vigorous exercise was associated with greater progression of CAC and plaque (calcification). This finding is consistent with cross-sectional observations of MARC-1, which showed that specific exercise intensities rapidly increase calcified plaque.
Very high-intensity exercise is associated with calcified plaque formation, suggesting that specific mechanisms may be involved in facilitating coronary atherosclerosis in athletes. For example, higher-intensity exercise produces higher catecholamine levels, which can increase a person's heart rate and blood pressure. According to previous studies, increased heart rate accelerates atherosclerosis, possibly due to increased frequency of turbulent blood flow.
No association was found between exercise volume and progression of coronary atherosclerosis during follow-up. The findings of this study are consistent with a previous study that showed 74% of recreational athletes had no significant difference in exercise volume between individuals with or without CAC progression after 4.1 years of follow-up. Exercise volume may be associated with the onset of coronary atherosclerosis but not with its progression. Further research is needed to determine differences in atherosclerosis based on exercise intensity, ie in separate groups (running and cycling).
