Footwear apparatus for facilitating optimal gaiting

A footwear apparatus for facilitating optimal gaiting, wherein the footwear apparatus comprises:

• an upper comprising a layer configured to form a foot space, wherein the upper is configured for retaining a foot of a user in the footwear apparatus;
• a sole comprising a front portion and a rear portion, wherein the upper is attached to the sole, wherein the rear portion is raised away from a plane defined by the front portion, wherein the rear portion contacts a heel portion of the foot when the footwear apparatus is worn on the foot, wherein the rear portion comprises a first attachment component;
• and
• a heel configured to be removably attached to the rear portion of the sole, wherein the heel comprises a second attachment component configured for mating with the first attachment component, wherein the removably attaching of the heel with the rear portion is based on the mating, wherein the sole is characterized by a stiffness, wherein the stiffness varies along the sole, wherein the stiffness of the rear portion is greater than the stiffness of the front portion, wherein the rear portion of the sole supports the heel portion of the foot of the user when the user runs while wearing the footwear apparatus without the heel, wherein a greater stiffness of the rear portion prevents an impact to the heel portion of the foot from an underside of the rear portion while running, wherein the sole comprises an interface region between the rear portion and the front portion, wherein the stiffness of the interface region is greater than that of each of the front portion and the rear portion excluding the interface region.