McDougall had been preaching the barefoot gospel to me for months. His own "conversion" took place over the past couple of years, after he investigated why he – and more than half of all runners – sustains so many injuries from simply jogging. Despite all the high-tech innovations, like gel-filled insoles, air cushions, and midfoot plates, built into today's near orthopedic shoes, research suggests that 40 to 80 percent of runners will get injured in any given year. So he was excited when he stumbled upon some loose research about the potential benefits of running barefoot, with one particular study citing the way the Tarahumara, an indigenous Mexican tribe, run (in leather sandals) without getting hurt.
McDougall made a good case, but I remained skeptical. I had a hard time believing that my 6-foot-4, 200-pound friend – whose running style resembled that of a drunken grizzly bear – truly ran well on pavement without shoes. This I had to see.
When I showed up, McDougall insisted I lose my shoes too. I immediately realized that running barefoot on pavement actually feels kind of nice. More surprisingly I began to run differently: Instead of pounding on my heels, the way I would in my cushy running shoes, the pavement forced me to land gently on the center of my foot and even slightly forward, so that my foot and lower leg could absorb the shock from the road.
Even more amazing was Chris's stride. In the past, he'd pound out the miles while emitting grunting or wheezing sounds that he'd compared to "Elvis's last shit." Now he lightly padded along, taking short strides, his feet hitting the ground almost silently, then flicking up behind him.
It felt so exhilarating to run barefoot that we cranked out three and a half hilly miles. But then the next day I woke up feeling like someone had driven six-inch nails through each of my calf muscles.
A couple of days later, my calves still throbbing, I walked into the lab of Irene Davis, a biomechanics professor at the University of Delaware. "Three miles is too much!" she scolded. "You should start with no more than a quarter mile."
I'd made a common barefooting mistake: too much too soon. But I hadn't come for a lesson. I wanted to understand why barefoot-style running might actually help me suffer fewer injuries.
Davis explained how muscles and ligaments come into play when we run – nearly all of them are essentially immobilized in modern running shoes. "I think we've trained our feet to be lazy," she said.
"To me, [running] shoes have changed the way we run," Davis said. "If you can change your stride to a more forefoot-oriented pattern, then you will reduce your risk of injury."
Davis had me run on a treadmill that measured my impact on the ground over each stride. "This is what causes injury," Davis said, circling a spike on a graph illustrating my foot strike with shoes on. "It represents the sharp impact of your heels hitting the ground. It's like a shock wave traveling up your body."
That shock wave was linked to knee and leg injuries, as well as plantar fasciitis, which is what inspired McDougall to give up his running shoes in the first place. The heel strike also causes pronation, the torquing of the foot that many of us buy special running shoes to try to correct. Corrective shoes, says Harvard's Lieberman, "solve the problem that they create." (Davis and Lieberman recently coauthored a study showing that barefoot runners experience a gentler impact.)
And yet, as my calves testified, going without shoes comes with its own pain.
"You're in shoes all of the time, and all of a sudden you're gonna run barefoot?" says champion ultrarunner Scott Jurek. "You need to graduate into it. A training period has to occur."
Jurek uses barefoot running as a part-time training tool. Once or twice a week, he'll add some barefoot running to his usual track workouts, jogging a mile in the infield or a couple of miles on a beach. "I look at it as strengthening as well as technique training," he says. "I'm not trying to run hard when I'm doing it. It's more of a warm-up kind of effort level."
Still, it's tempting to want to do more. That's what Leon Kelly did. A 33-year-old Manhattan lawyer and fitness buff who became curious about barefoot running last April, Kelly started slowly at first (or so he thought), jogging 20 minutes on grass three times a week. After a month he included pavement in his runs. Even then, he kept to a modest 20 miles per week. But by early July he had to stop running altogether due to knee pain. "It felt so right; I think I ran too hard too soon," he says. "In hindsight I didn't allow my body sufficient time to adapt."
"Anytime you make a change like that, you're just changing the kinds of injuries you're going to get," says Joseph Hamill, a biomechanics professor at the University of Massachusetts. "People are looking for a silver bullet, but there's no panacea."
"If you're doing fine, and you're not getting injured, I'm not going to tell you to change how you run," adds Davis. "Most of the people who've switched to barefoot have done so because they got injured."