Foot strike patterns and collision forces in habitually barefoot versus shod runners
Daniel E. Lieberman, et al.
Nature 463, 531-535(28 January 2010)
A softer ride for barefoot runners
People who run long distances without shoes cushion the blow with their gait.
Vertical ground reaction forces and foot kinematics for three foot strikes at 3.5 m s-1 in the same runner (Figures)