Running sans sneakers is the latest craze among athletes training to go the distance. Now, along comes a study that suggests the foot is well-adapted to long-distance running without shoes, and that running barefoot or with minimal footwear is the way to avoid injury and pain. After all, our ancestors did it. And, didn’t we run barefoot as children?

Turns out that the runner at your health club who has shucked his Brooks and is lapping you on the track is performing the way adults should run, says Harvard researcher Daniel Lieberman, PhD of human evolutionary biology and lead author for the study, which was published in the scientific journal Nature.

Scientists have found that those who run barefoot, or in minimal footwear, have a very different stride from their shoe-wearing peers. The sneaker-less tend to avoid "heel-striking," and instead land on the ball of the foot or the middle of the foot. By landing on the middle or front of the foot, barefoot runners have almost no impact collision, much less than most shod runners generate when they heel-strike.

“Most people today think barefoot running is dangerous and hurts, but actually you can run barefoot on the world's hardest surfaces without the slightest discomfort and pain,” says Lieberman. “All you need is a few calluses to avoid roughing up the skin of the foot. Further, it might be less injurious than the way some people run in shoes."

Working with populations of runners in the United States and Kenya, Lieberman and his colleagues at Harvard, the University of Glasgow, and Moi University looked at the running gaits of three groups: those who had always run barefoot, those who had always worn shoes, and those who had converted to barefoot running from shod running. The researchers found a striking pattern.

 “People have been running barefoot for millions of years and it has only been since 1972 that people have been wearing shoes with thick, synthetic heels,” says Lieberman.

Lieberman says, studies suggest that at least 30% of runners get injured every year, and many of these injuries stem from problems that arise in the foot or lower leg. Cushioned sneaker heels have allowed runners to change their stride to high-impact running, and likely open up a whole world of pain involving foot and leg injuries.

“Our research asked how and why humans can and did run comfortably without modern running shoes,” says Lieberman.

He adds that researchers confirmed what many people – and now barefoot running proponents are praising as the stride dujour:  "Our feet were made in part for running," Lieberman says.”

But he cautions barefoot running enthusiasts to tread lightly.  For modern humans who have grown up wearing shoes, barefoot or minimal shoe running is something to be eased into.

"Running barefoot or in minimal shoes is fun but uses different muscles," says Lieberman. "If you've been a heel-striker all your life you have to transition slowly to build strength in your calf and foot muscles."

He hopes the research can be used to provide insight into preventing repetitive stress injuries that afflict a high percentage of runners today.