Patent ID: 6964119
Filing Date: 2005-11-15
Classification: A43B

Abstract:
1. An article of footwear comprising: an upper portion forming a shell, said shell having a heel portion and a toe region; a sole, said sole having a heel portion and a toe portion; and an energy storage system, said energy storage system extending between said upper portion and said sole, said energy storage system comprising a first spring provided at or adjacent a medial side of said shell and a second spring provided at or adjacent a lateral side of said shell, each of said springs having a generally C-shape with an upper portion and a lower portion interconnected by an intermediate portion, said upper portions rolling forward relative to said lower portions when said sole makes contact with a ground surface such that said upper portions' moment arms relative to said intermediate portions decrease when said upper portions roll forward to thereby increase the stiffness of said springs wherein said springs convert an impact force generated by the user at or near said heel portion of said shell into a propulsion force to thereby enhance a user's performance.