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When you strap on a typical running shoe, you may be fighting evolution.

Modern-day running shoes have changed the way people run, altering our gait from that of barefoot running — the manner by which people ran for thousands of years before the arrival of the cushioned shoes found on store shelves today — a new study suggests.

The study showed barefoot runners tend to hit the ground toe first, a style that minimizes forces that jar the body, while people used to running shoes have largely adopted a heel-first style that can mean lots of force on the body.

While several studies have compared running barefoot to running with shoes, the current study, published this week in the journal Nature, is the first to include analyses of runners who have never worn modern footwear, the researchers say.

Humans started wearing running shoes only relatively recently, with use of this footwear taking off in the last 40 years. Before that, people either ran barefoot or wore shoes that would seem to offer little protection from the ground, such as sandals or moccasins.

For nearly as long, people have debated which is better. While the new study may not solve the vigorous debate, it does add data on the physiological effects of running shoes.

The researchers aren’t suggesting runners ditch their shoes. For one, barefoot running can take getting used to, and it takes stronger muscles, so the switch could lead to tendonitis.