For some people, running a marathon is not just an event, it’s a way of life. But can too much running cause more harm than good? A new study which recently got a lot of press suggests that it may be possible to exercise too much—but also that it may not matter much. It’s a little confusing, so let’s take a closer look…

The New Findings

Researchers followed 21,758 male runners for 15 years. The runners reported their physical activity based on exercise type and intensity. Then, the researchers separated the participants into three groups based on how much they exercised per week. The participants also agreed to a scan that measures plaque buildup in their arteries. Researchers found that men in the highest exercise group were 11% more likely to have more plaque buildup in their arteries compared to those who exercise less. However, those same men (who exercised more and had the plaques) lived just as long as people who exercised less. In fact, their overall risk of dying during the study time period was actually lower(!).

Whoa, What Does This All Mean?

Importantly, this study did not control for lifestyle habits (diet, sleep, etc.), so we can’t say for sure that plaque build-up and exercise habits are connected. Additionally, researchers only looked at male runners—so what about the ladies? Well, a different study looking at women specifically, also found similar results. So, there’s decent evidence suggesting that more exercise may not necessarily hurt you, but it doesn’t really offer any additional protection.

How Much is Too Much?

Too much exercise may have some negative side effects, but a balanced exercise program can be very beneficial. Moderate exercise has been shown to improve brain function and even increase longevity. What’s the magic amount? Well, it depends on your preferences, but here are some guidelines from the American Heart Association to get you started.