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expert reaction to study looking at physical activity and the coronary artery calcium score (CAC score)

Research, published in the journal Heart, looked at physical activity and the coronary artery calcium score (CAC score).


Prof Gavin Sandercock, Professor in the School of Sport, Rehabilitation and Exercise Sciences, University of Essex, said:

Does the press release accurately reflect the science?

“Yes, except the title of the press-release is misleading as the CAC score used is not a ‘heart attack risk factor’ at all.  It should also be noted that the CAC (calcification) score does not measure artery hardening – this term is not used in the paper.

Is this good quality research?  Are the conclusions backed up by solid data?


Have the authors accounted for confounders?  Are there important limitations to be aware of?

“Yes, mostly.  There are two important limitations – the paper does not show that people who do a lot of physical activity have more calcified arteries – it shows people who say (or think) they do a lot of physical activity have more calcified arteries.  The study did not measure any heart disease outcomes such as heart attacks or stroke so it is difficult to speculate on the importance the findings have in relation to health.

What are the implications in the real world?   Is there any overspeculation?

“The suggestion that exercise may modify the effects of diet, vitamins and minerals is overspeculation as none of these factors were measured in the study.

Should people assume this paper means ‘exercise is bad for your heart’?

“Not at all, quite the opposite in fact.  Athletes also have higher CAC scores but much lower risks of heart disease.  The problem is that ‘hardening’ or calcification of arteries sounds like a bad thing when actually, adding calcium to damaged areas (plaques) on the inside walls of arteries makes them more stable, less likely to break off and form clots that lead to heart attacks and stroke.  The authors do state this referring to accelerated plaque healing and stabilisation: “physical activity may accelerate the progression of coronary calcium, possibly due to plaque healing, stabilisation”.  The NHS1, The British Heart Foundation2, The European Society of Cardiology3, The American Heart association4 and World Health Organisation5 all agree with the prevailing view based on scientific evidence that ‘a lack of physical activity’ is a risk factor for atherosclerosis and heart disease.”







Prof Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said:

“This is an interesting paper which supports that higher self-reported activity levels are associated with more calcification in the arteries of the heart, a commonly used test to predict future risk of heart disease or stroke.  However, this work cannot be taken to infer physical activity is harmful to the heart since we know that other interventions that can increase heart calcification levels, such as statins, also lessen heart disease.  These apparent paradoxes may be explained by certain interventions – such as activity or lowering cholesterol – working to stabilise ‘vulnerable’ plaques in the heart that are more likely to rupture, with higher calcification levels seen with these interventions indicative of more stable plaques.  Also, there is overwhelming evidence that being greater activity levels reduce future heart attacks and strokes, and improve quality of life.  Hence, no one should stop being active based on such findings.  Rather regular, sustained physical activity remains one of the best ways to keep healthy lifelong, with the key to finding fun or necessary ways to keep active.”




‘Physical activity and the progression of coronary artery calcification’ by Ki-Chul Sung et al. was published in Heart at 23:30 UK time on Monday 20 September 2021.

DOI: 10.1136/heartjnl-2021-319346


Declared interests

Prof Gavin Sandercock: “I have no conflicts of interest to declare.”

Prof Naveed Sattar: “I love being active – dog walks, cycling etc.”

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