About 1 in 4 older male athletes who train regularly have significant plaque buildup in their heart arteries, even if they feel fine and have no symptoms.

Older male athletes who have high heart disease risk and train a lot are much more likely to have serious plaque buildup in their heart arteries than those who train just as much but have lower heart risk.

If an athlete has a high calcium score on a heart scan (over 100), doctors should treat them like someone with early heart disease — lower their bad cholesterol and test how their heart handles exercise.

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 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.

Even though endurance athletes and healthy non-athletes have about the same amount of calcium in their heart arteries, the athletes’ calcium levels are higher than 90% of people their age, suggesting their arteries are aging faster from exercise.