Abstract: An article of footwear comprises an outsole that has a bottom portion and a medial arch portion extending upward from the bottom portion. The medial arch portion of the outsole has a base and a plurality of protrusions extending outward from the base. The plurality of protrusions are arranged in vertical alignments. In each one of the vertical alignments, at least one protrusion of the plurality of protrusions is closer to the bottom portion and has a larger effective diameter than at least one other protrusion of the plurality of protrusions that is further from the bottom portion.

Abstract: An article of footwear includes an outsole having a heel region, a midfoot region, and a forefoot region. An outer midsole layer is secured to the outsole and extends only over the heel region and at least some of the midfoot region. An inner midsole layer is supported by the outer midsole layer and the outsole without being fixed thereto, and extends over the heel region, the midfoot region, and the forefoot region. The outer midsole layer is configured to surround a periphery of the inner midsole layer at the heel region. The outsole may include lateral and medial arch portions for traction.