Patent ID: 8387279

Claim:
A shoe sole for an article of footwear, said shoe sole comprising: a heel portion, a midfoot portion, and a forefoot portion; a medial side and a lateral side; and a midsole, said midsole comprising: an upper surface, said upper surface having a width that underlies and supports a wearer's foot; an upper midsole portion and a lower midsole portion disposed adjacent and below said upper midsole portion in at least said heel portion; a lower surface; and a peripheral sidewall between said upper surface and said lower surface, wherein said upper midsole portion of at least said heel portion is undercut at its periphery to define a horizontal indentation having a depth in said peripheral sidewall of said midsole along said medial and lateral side and a balancing portion therebetween, said horizontal indentation further extending along a rear of said heel portion, said peripheral sidewall comprising an upper peripheral sidewall angled upward from said horizontal indentation toward said upper surface and a lower peripheral sidewall angled downward from said horizontal indentation toward said lower surface to form a peripheral gap that widens in a direction away from a center of said shoe sole, and wherein said balancing portion has a width less than said width of said upper surface of said midsole, said midsole being adapted to upset a wearer's balance transversely to a longitudinal axis of said shoe sole, thereby forcing a wearer of said article of footwear to adjust one's walking gait to maintain a center of pressure over said balancing portion, and wherein said depth of said horizontal indentation varies along its length.