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.

Athletes who train the most, especially with high intensity, are more likely to have heavy calcium buildup in their heart arteries, which is a sign of advanced artery disease.

Watches and fitness trackers that measure training intensity and duration are better at linking exercise to heart plaque than asking athletes to remember how much they trained.

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.

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.

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.