Hopefully this is the right place to put this. I just heard this on NPR. Many Kenyans (including Olympic runners) run barefoot. Running barefoot is different than shoes because you land on the ball of your foot rather than the heel. They found that there is less shock to your body, but need more strength in your calf and feet muscles to run this way.

http://www.npr.org/templates/story/...oryId=123031997