Men who exercise moderately — like running a few times a week — tend to have less calcium buildup in their heart arteries than men who don’t exercise much.

Men who train extremely hard for endurance sports like marathons or triathlons for many years tend to have more calcium buildup in their heart arteries than men who exercise moderately, even though they’re otherwise healthy.

Men who have trained for decades in marathons and endurance sports are more likely to have calcium deposits in their heart arteries than men who don't exercise much—even if they're otherwise healthy and have no heart disease risk factors.

The plaque buildup in endurance athletes is mostly hard, chalky calcium, while in non-athletes it’s softer and greasier—this might make athlete plaques less likely to suddenly break and cause heart attacks.

Women who train hard for endurance sports — even very hard — tend to have less calcium buildup in their heart arteries than women who don’t exercise much.

Even though super-active athletes have more plaque in their heart arteries, the plaque they have is harder and less dangerous-looking than the softer, riskier kind seen in less active people.