An item of footwear for a wearer, the item of footwear comprising a flexible sole structure that comprises a heel segment having horizontal upper and lower surfaces combined with other sole segments having arch (instep) and toe upper surfaces that are horizontal when unloaded, but that assume a negative upper surface slope when loaded, and with arch and toe lower surfaces that have a negative lower surface slope with unloaded, but that assume a horizontal position when loaded. In use, the item of footwear is operative to reduce the likelihood that a wearer having one of a variety of anatomical leg forms would fall outwardly (laterally) from his or her vertical plane.