TITLE: Athletic Footwear: Unsafe Due to Perceptual Illusions 1991-1.pdf

Accessible Summary:

Purpose: To evaluate the importance of shear stress in plantar sensory processes.

Synopsis: An experiment was performed in which heavy horizontal and vertical loads (the range seen in running) were applied to the sole of the foot supported by a rigid testing surface with various materials placed between the foot and surface.  High levels of discomfort required application of both vertical and horizontal load and a support surface that causes small surface deformations (n this case small gravel). 

Significance: This was this first published report indicating that the combination of vertical deformation and shear stress is essential to initiate behavior that can alter impact. This indicated it would be impossible to duplicate the barefoot condition in shoes because there is no conceivable way of adding plantar shear stress to footwear.