Shoe sole having insert with graduated cushioning properties

A shoe sole comprising:

• an outsole having lower and upper surfaces, with a recess being formed in the upper surface, the interior of the recess comprising a generally flat bottom surface;
• and
• an insert formed of a resilient material that fits in the recess in the outsole, the insert having an insert bottom that rests on the bottom surface of the outsole recess, the insert bottom comprising a plurality of longitudinally spaced, downwardly extending, transverse ribs, the ribs being of at least two lengths so as to include longer and shorter ribs, the longer ribs alternating with the shorter ribs in a regular pattern along the longitudinal length of the insert, the longer ribs terminating in distal ends that rest on the bottom surface of the outsole recess, the shorter ribs terminating in distal ends that are raised above and spaced away from said bottom surface when the insert is in an uncompressed condition, the insert thus providing a variable cushioning rate for a user's foot, the longer ribs providing a first cushioning rate for initial compression of the insert, the shorter ribs providing supplemental cushioning when the longer ribs are compressed to the point where the shorter ribs engage the bottom surface, thus providing a stiffer second cushioning rate for further compression of the insert, the variable cushioning rates providing a soft feel on initial compression and a stronger resistance to compression upon further compression of the insert, at least some of the transverse ribs being formed with alternating portions of different lengths as the ribs extend from one side to the other side of the insert, the different length portions of the individual ribs providing a graduated cushioning rate for the individual ribs.