A group of hardcore runners was extolling the virtues of Vibram Five Fingers, a brand of footwear that features a slender rubber sole and a separate pocket for each toe, when someone remarked that they found the Vibrams hard to wear and thought they made their feet look like a Muppet's. This stopped the conversation cold. You'd have thought they claimed to support terrorism against puppies.
Barefoot or minimalist shoes have garnered quite the rabid fan base in the past few years. The credit for making them mainstream goes to Chris McDougall, author of the excellent book "Born to Run," which explores the life and running habits of the Tarahumara Indians of Mexico's Copper Canyon, arguably the greatest distance runners in the world.
In the book, McDougall explains how running sans shoes or in minimal footwear has taught him to shorten his running stride to a more natural length and land closer to the ball of his foot, thereby allowing his feet and ankles to become the flexible shock absorbers they were meant to be.
This, he claims, is closer to the way our primal ancestors ran when they hunted and gathered for a living, compared to running in a typical modern running shoe, which forces your weight backward so you tend to strike onto your heel as you land. He and other barefoot proponents believe that retraining your 21st century foot to stay up off the heel will result in fewer sore knees and swollen ankles.
Not everyone is on board with this idea however. It's a hotly debated subject that apparently will get you snubbed at parties. It's also started some pretty spirited disagreements in the lab.
"When you run closer to the forefoot as you do with barefoot running or when you practice a barefoot running style you lose what we call the initial impact peak, which is the force that shoots up through your ankles, knees and hips and this might be injury protective," said Reed Ferber, director of the Running Injury Clinic at the University of Calgary in Canada. "That being said, you also shorten your stride length, so you take more footfalls. This means you'll absorb more maximum load over time, which could potentially be more injury causative."
Studies have found that the average barefoot runner's stride is about seven centimeters shorter than normal. Over the course of a marathon, that translates to about 7,000 additional footfalls above the 40,000 steps a typical racer will take to cover the 26.2-mile distance.
"There's less force per step, but that's a lot of extra steps to take where something potentially can go wrong," Ferber said.
Though no major studies have been completed to show whether barefoot runners are sidelined more or less often than those wearing conventional shoes -- Ferber's lab currently has one under way -- based on the evidence so far, Ferber said he feels it's a push. "I suspect they probably trade one type of injury for another."
Irene Davis, professor in the program of physical therapy at the University of Delaware, couldn't disagree more.