An improved sole for use with footwear is disclosed. The sole includes at least one layer of material which is adapted to be attached to an upper of the footwear. A distal flex groove is formed in the sole and is coextensive with a medial metatarsal-phalanges line which extends between the first and second metatarsal-phalanges joints. A proximal flex groove is also formed in the sole and extends substantially parallel to a lateral metatarsal-phalanges line which extends along the second through fifth metatarsal-phalanges joints. The proximal and distal grooves join on another at the medial edge of the sole adjacent the first metatarsal-phalanges joint.