Nike Free Or Die
Lieberman found that runners in shoes usually landed heel-first. Barefoot runners landed farther forward, either on the ball of their foot or somewhere in the middle of the foot, and then the heel came down — much less collisional force.
And people who switched from shoes to barefoot running eventually, without prompting, adopted the barefoot style.
Turns out that the way in which barefoot runners run seems to store up more energy. It allows the arch of the foot and the calf muscles to act as a better spring and to store up energy, and then give it back in the beginning of the next step
Personally interesting, since I have been running barefoot on the treadmill for the last 6 years. This year, I am planning on regular barefoot hiking (in addition to the ritual barefoot trek).