The argument that feet were designed for barefoot locomotion is flawed.
Does the barefoot style reduce a runner’s risk of pain and injury (as barefoot enthusiasts believe)? Or does barefoot running simply contribute to the development of a different set of injuries in some runners?
Dr. Ridge’s shod volunteers all started the study with normal feet and lower legs, according to their M.R.I. scans, which were read by multiple radiologists.
She then randomly assigned half of the group to continue running as they had: same mileage, same shoes.
The other half were given a pair of Vibram Five Fingers barefoot-style shoes and asked to begin sprinkling barefoot-like mileage into their runs, but gradually. They were told to wear the minimalist shoes for one mile during the first week of the study, two miles the second, three the third, and then as much as they liked, which is what the Vibram Web site recommended at the time of the 2011 study.
After 10 weeks, both groups of runners received a follow-up M.R.I. There was no evidence of injuries to or changes in the tissues of the lower leg, like the Achilles’ tendon, among any of the runners. But more than half of the runners wearing the minimalist shoes now showed early signs of bone injuries in their feet. [emphasis mine]