Researchers at Harvard Medical School took a different approach to better understanding running injuries—they studied runners who have never been injured.

The Harvard Gazette reported on the study, led by Harvard professor Irene Davis, which examined 249 runners who run at least 20 miles a week and are heel strikers (since most runners are). The study followed the runners via a questionnaire for two years. After the two years, they divided the runners up into those who had been injured and those who hadn’t. They further separated them by runners who were injured seriously enough to require medical attention, and those who have never had a running injury in their life. They then compared the biomechanical trends of those groups.

The findings?

The “vertical average loading rate” varied sharply between the two groups, with the never-injured runners having the lowest rate.

Furthermore, Harvard researchers discovered that the suddenness of impact correlated to running injuries. In other words, those who land softly stayed healthy, while “stompers” tend to get injured more.

RELATED: Are You a Stomper?

Weight played no factor—some heavier runners land softly, and some lighter runners are stompers.

One tip to develop a softer landing? Listen to your steps.

“If you land louder, it’s harder,” Davis told the Harvard Gazette.

RELATED: Footstrike 101: How Should Your Foot Hit the Ground?

MORE: Harvard Gazette