Toe Huggers

In retrospect, the timing of my barefoot-running experiment — in New York City, in January, in the middle of one of the worst cold snaps in memory — may not have been ideal. But I was willing to risk toe frostbite to find out why a growing number of trainers and scientists believe that ditching cushioned soles might be the best way to protect joggers against chronic injuries.

Because the human foot has relatively little padding on the heel, barefoot runners tread more lightly, landing on the outer part of the midfoot and then rolling inward. Cushiony running shoes, by contrast,...