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.

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.

Even though athletes have more plaque, it’s usually hard and chalky, not soft and gooey — so it’s less likely to suddenly break off and cause a heart attack.

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.

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.

Older athletes who train hard for many years tend to have more calcium deposits and fatty buildups in their heart arteries, but these buildups are usually hard and stable, not soft and dangerous.