A midsole assembly for an athletic shoe includes a midsole formed of soft elastic material, a corrugated sheet interposed in the heel portion of the midsole, a plurality of transverse holes formed at the contact regions of the midsole with the corrugated sheet, and through holes extending vertically...http://www.google.co.uk/patents/US6393732?utm_source=gb-gplus-sharePatent US6393732 - Athletic shoe midsole design and construction
