A midsole assembly for an athletic shoe includes a midsole formed of soft elastic material, and a corrugated sheet disposed in at least a heel portion of the midsole. The amplitude of the wave configuration of the corrugated sheet is larger at the medial and lateral sides of the heel portion and smaller...http://www.google.sh/patents/US6314664?utm_source=gb-gplus-sharePatent US6314664 - Athletic shoe midsole design and construction
