What?? Intense Exercise Results In More Coronary Calcification, But Keep Doing It?

Physical activity and exercise training are associated with a lower risk for coronary events.

Puzzling for sure is that prior studies of middle-aged and older male athletes revealed increased coronary artery calcification (CAC) and atherosclerotic plaques, which were related to the amount and intensity of lifelong exercise.

Does exercise actually drive the degree of calcified plaque in arteries upwards? And what aspect of exercise?  New data show that the intensity of exercise over 6 years is related to increased calcification and plaque in heart arteries although the risk is low. 

STUDY DESIGN

Middle-aged and older men from the MARC-1 (Measuring Athlete's Risk of Cardiovascular Events 1) study were invited for follow-up in MARC-2 (Measuring Athlete's Risk of Cardiovascular Events 2) study. The prevalence and severity of CAC and plaques were determined by coronary computed tomography angiography.

The volume (metabolic equivalent of task [MET] hours/week) and intensity (moderate [3 to 6 MET hours/week]; vigorous [6 to 9 MET hours/week]; and very vigorous [≥9 MET hours/week]) of exercise training were quantified during follow-up. 

RESULTS

Overall, 289 of the original 318 men in a trial called MARC-1 completed repeat heart imaging at a follow-up of 6.3 years. Participants exercised for 41 (25 to 57) MET hours/week during follow-up, of which 0% was at moderate intensity, 44% was at a vigorous intensity, and 34% was at very vigorous intensity.

The prevalence of CAC increased from 52% to 71% during the follow-up. CAC  was present in  151  (52%)  men at baseline and increased to  205  (71%)  men at follow-up.  CAC  scores  ≥100  increased from  15%  to 31%, CAC scores ≥400 increased from 6% to 13%, and  CAC  scores  ≥1000  increased from  1%  to  6%  at follow-up.

Plaque prevalence increased from 64% at baseline to 83% at follow-up. A total of 216 (75%) participants showed an increased number of coronary atherosclerotic plaques.

Exercise volume during follow-up was not associated with changes in CAC or plaque.

Very vigorous intensity exercise was associated with a greater increase in CAC score. Very vigorous exercise was also associated with increased odds of plaque progression.

CONCLUSIONS

Exercise intensity but not volume was associated with the progression of coronary atherosclerosis during the 6-year follow-up.

It is intriguing that very vigorous intensity exercise was associated with greater CAC and calcified plaque progression, whereas vigorous intensity exercise was associated with less CAC progression.

The effect of very vigorous-intensity exercise may mimic the effect of statins on CAC and plaque composition.  Statins increase plaque calcification in some studies, 33, but decrease atheroma volume and cardiovascular risk.

Further studies will be needed to assess if moderate exercise is the optimal sweet spot for CAC and plaque as well as any events these participants may have.