From our large butt muscles, a supportive head ligament and the springy achilles tendon, our bodies are designed to run, says Christopher McDougall. History says humans used to run a bunch, and their strides did not mimic the running-shoe-cushioned stride of today.

Before Nike's 1972 invention of the modern running shoe, runners couldn't land on their heels. It simply hurt too much. Today's technology allows a heel strike, which means excessive foot rolling -- aka overpronation. Research points to deconditioned foot muscles as the major culprit underlying the plethora of running injuries, further supported by an injury rate that's inched up the past 40 years. McDougall says it's not running that's hurting you, it's the shoes.

After McDougall researched the Tarahumara -- a Mexican Indian tribe that runs 150 miles for fun in skimpy sandals -- and wrote a book about them, he switched to barefoot running, too. An avid runner, McDougall's chronic foot and knee ailments disappeared. Now he wears a thin rubber sock on his foot to guard against abrasions. Wonder if it protects against glass? For now, I'm only barefoot on the beach. Looks like the shoe industry might be listening, there's a trend toward minimal shoe designs.

Would you run barefoot like the Tarahumara?