Even after accounting for things like cholesterol and blood pressure, the more hours someone spends training over the year, the more likely they are to have plaque in their heart arteries.

Just doing short, intense workouts isn’t linked to more heart plaque—what matters more is how many total hours you spend training over time.

People who train hard and regularly for endurance sports are less likely to have dangerous, unstable plaque in their heart arteries that could suddenly cause a heart attack.

Men who train a lot for years—especially long hours at high intensity—tend to have more plaque in their heart arteries, even if 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.

For older male athletes, how much they exercise overall doesn’t seem to affect whether their heart arteries get more calcium buildup over time—it’s more about how hard they push during workouts.