Does running really harden your arteries?

On Tuesday, the journal Circulation published three articles—two new studies plus an editorial—that answer some longstanding questions and raise new ones about the link between high levels of running and the health of your coronary arteries. The news is mostly reassuring for runners, but it’s worth taking some time to understand what the new data tell us.

For many decades, the relationship between exercise and heart health was presumed to be simple: the more you do, the less likely you are to suffer heart problems. But in the last decade, that orthodoxy has been questioned, in part because we now have, for the first time, a generation of adults reaching retirement age who have been running (and doing other forms of endurance exercise) for nearly their entire adult lives. Being “active” is one thing; but if you’re running multiple marathons a year for four decades, does that eventually take a toll on your ticker?

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For a general overview of this issue, check out my in-depth feature in Runner’s World from last fall. What the new studies in Circulation deal with is one particular aspect of the debate, related to the likelihood of developing blockages in the arteries leading to your heart.

In 2008, contrary to conventional wisdom, a study in Germany found that a group of marathon runners had higher “coronary artery calcium” (CAC) scores than a matched group of controls. CAC scores, which use CT scans to assess how much calcium has accumulated in your coronary arteries, quantify the degree to which artery-hardening plaques have built up in your blood vessels.