Intense Exercise Linked to Higher Coronary Calcium Scores, But Risk Remains Unclear

Key Takeaways

Exercise is linked to increased coronary artery calcium (CAC) scores, but this may indicate stable plaque rather than higher heart attack risk.
The study is observational and does not prove that exercise causes harmful calcification—more research is needed.
People with high cardiac risk should consult a doctor before engaging in intense physical activity to balance heart health benefits with potential risks.

Exercising may paradoxically accelerate the worsening of an important risk factor for heart attacks: calcium deposits in coronary arteries, one of the most important markers used to assess cardiovascular disease risk. In a new study done by a team of doctors from 2 major health centers in Seoul and Suwon (South Korea) and which was published in the journal Heart the researchers do not dispute the cardiovascular benefits of exercise but suggest that in some patients, clinicians should consider that exercise may be associated with increased CAC scores, but this may reflect stable plaque formation rather than an increased risk of heart disease.”

Coronary Deposits

The coronary artery calcium score (CAC) is used to guide treatments that are aimed to reduce the risk of heart attacks and strokes. In fact, statins are now indicated for most people with a CAC score of 100 or more.

Can exercise worsen arterial stiffness?

This study showed that despite significant health benefits – including reductions in the risk of obesity, diabetes, heart attacks, and death, among others – people that are very active physically appear to have increased levels of calcium in their coronary arteries. While a correlation was observed, more research is needed to determine whether exercise directly contributes to arterial stiffness or if increased CAC scores represent stable, less harmful plaques.

The Kangbuk Samsung Health study

the Korean team subjected 25,485 participants (22,741 men and 2,744 women), aged 30 years and older, to extensive health checks between March 2011 and December 2017. At each check-up, participants provided information on their medical and family history, lifestyle, and education, and their weight (BMI), blood pressure, and blood lipids were also assessed. Their exercise or physical activity was also recorded. Finally, any calcification of the coronary arteries was assessed and monitored using the CAC score over an average period of 3 years.

47% (11,920) of the participants were inactive
38% (9,683) were moderately active
15% (3,882) were vigorously active (6.5 km of running per day)

The analysis showed:

The more physically active participants were likely to be older and smoke less than the less active participants.
Their total cholesterol was lower but had higher blood pressure, and evidence of calcium deposits in the arteries.
A relationship between physical activity levels and the progression of coronary calcification over time, regardless of CAC scores at the start of the control period,
The estimated CAC calcification scores in the 3 groups at inclusion were 9.45, 10.20, and 12.04, respectively,
Increased intensity of physical activity was associated with a faster increase in CAC scores in both those that started without calcification and those with baseline CAC scores.
Compared with inactive participants, the mean increase in CAC scores over 5 years for moderately and vigorously active participants was 3.20 and 8.16, respectively, even after controlling for potential confounding factors such as BMI, blood pressure, and blood lipids.

Physical activity, a potential factor in coronary atherosclerosis

Researchers observed a link between exercise and rising CAC scores, though this does not confirm exercise directly causes harmful arterial calcification. The authors concluded that it is possible that physical activity increases coronary atherosclerosis or arterial stenosis through the effect of mechanical stress and damage to the vascular wall. Physical activity may also induce these calcification and atherosclerotic effects through physiological responses such as an increase in blood pressure and parathyroid hormone levels. In addition, exercise can indirectly alter food, vitamin, and mineral intake.

FAQs

Does this study mean exercise is bad for the heart?
No. Exercise has proven cardiovascular benefits. The study only found an association between high physical activity and increased CAC scores, which may indicate stable, non-dangerous plaque.

Should I stop exercising if I have a high CAC score?
Not necessarily. Speak with your doctor, as increased CAC may not always mean a higher risk of heart attacks. Individual risk factors matter.

How much exercise is too much?
There’s no universal limit, but excessive endurance training may require medical supervision, especially for individuals with existing heart conditions.

Bottom Line

This study challenges the common belief that more exercise always means a healthier heart. While it links high physical activity to increased CAC scores, it doesn’t prove that exercise causes harmful blockages or higher heart attack risk. But what else could be at play? The study didn’t consider plaque composition—is the calcium buildup from exercise stabilizing arteries rather than clogging them? It also didn’t track actual heart attacks or strokes, meaning we don’t know if these rising CAC scores translate to worse outcomes. Other factors, like genetics, inflammation, diet, and even recovery time, weren’t fully explored. Could extreme exercise trigger stress responses that affect arterial health differently in some people? Instead of fearing exercise, the real takeaway is that heart health isn’t one-size-fits-all. Personalized risk assessments—not just CAC scores—should guide fitness decisions.

References

Sung, K.-C., Hong, Y. S., Lee, J.-Y., Lee, S.-J., Chang, Y., Ryu, S., Zhao, D., Cho, J., Guallar, E., & Lima, J. A. C. (2021). Physical activity and the progression of coronary artery calcification. Heart, 107(21), 1710-1716. https://doi.org/10.1136/heartjnl-2021-319346

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