portion of the shoe to the lateral side of a shoe 300 in one embodiment the stiffness of the extended sidewall portion 215 or the extended elongated portion 214 or both increases continuously along the medial and lateral sides toward the rear of the extended heel portion 213 in another embodiment the stiffness of the extended sidewall portion 215 the extended elongated portion 214 or both decreases continuously along the medial and lateral sides toward the rear 216 of the extended heel portion 213 fig1 shows another embodiment of a stabilizing device 401 mounted in a shoe 400 with an extended heel portion 213 wherein the elongated portion 204 and sidewall portion 205 are positioned along both the medial and lateral sides of the shoe 400 the extended elongated portion 214 is integrally formed with elongated portions 204 located on both the medial and the lateral side the extended sidewall portion 215 is integrally formed with the sidewall portions 205 on the medial and lateral sides in this embodiment the sidewall portions extend into the forefoot region as can be seen most clearly in fig3 the stabilizing device of the present invention is preferably formed as a monolithic seamless piece with the elongated portion 204 704 gradually curving upward to blend into the upper portion of the sidewall portion 205 705 preferably the stabilizing device of the present invention is formed using an injection molding process that allows precise formation of a predetermined continuously and smoothly varying stiffness profile the stabilizing device is preferably formed of a thermoplastic material most preferably a soft thermoplastic injection molded material such as thermoplastic polyurethane u201c tpu u201d however any other material which exhibits well defined stiffness.