Footwear with balancing structure

Abstract

The inventive subject matter is directed to a sole unit for an item of footwear having a forefoot region, a midfoot region and a rearfoot region. The mid foot region includes a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.

1 . A sole unit for an item of footwear, comprising:
 a forefoot region, a midfoot region and a rearfoot region;   wherein the mid foot region comprises a balancing structure having a curved surface profile that rotates around (i) an axis for fore-aft pivoting or balancing and/or (ii) an axis for lateral-medial pivoting or balancing, when the item of footwear is under a normal load of a user.   
     
     
         2 . The sole unit of  claim 1  wherein the a balance structure is defined by material having a higher durometer than the durometer of the adjacent forefoot and rearfoot regions so that the forefoot and rearfoot regions preferentially compress relative to the midfoot region, leaving the midfoot region as a protrusion for balancing. 
     
     
         3 . The sole unit of  claim 1  wherein the midfoot region has a durometer of about 60 C to about 80 C, and the forefoot and midfoot regions each have a durometer at least 10 C below the durometer of the midfoot region. 
     
     
         4 . The sole unit of  claim 3  wherein the durometer of the balancing structure is about 60 C to about 80 C. 
     
     
         5 . The sole unit of  claim 1  wherein the balancing structure comprises a rounded structure protruding from a recessed midfoot area. 
     
     
         6 . The sole unit of  claim 5  wherein the rounding of the structure allows for fore-aft rocking. 
     
     
         7 . The sole unit of  claim 5  wherein the rounding of the structure allows for lateral-medial rocking. 
     
     
         8 . The sole unit of  claim 5  where the rounding of the structure allows for both fore-aft rocking and lateral-medial rocking. 
     
     
         9 . The sole unit of  claim 1  wherein the curved profile is provided by a polygonal structure having more than four sides. 
     
     
         10 . The sole unit of  claim 1  wherein the curved profile is provided by a balancing structure having varying durometer. 
     
     
         11 . The sole unit of  claim 1  wherein the sole unit comprises a monolithic structure. 
     
     
         12 . The sole unit of  claim 1  wherein the monolithic structure is of a heterogeneous nature and the balancing structure has a relatively higher durometer than adjacent forefoot and rearfoot regions. 
     
     
         13 . The sole unit of  claim 1  wherein the sole unit comprises a modular assembly of a plurality of layers, one or more layers contributing to the structure of the balancing structure. 
     
     
         14 . The sole unit of  claim 1  wherein one layer comprises a core layer with the balancing structure disposed thereon. 
     
     
         15 . The sole unit of  claim 14  wherein a second layer comprises a stability layer comprising a cushioning element. 
     
     
         16 . The sole unit of  claim 15  wherein the core layer is disposed above the stability layer and the stability layer has a window or frame through which the balancing structure protrudes. 
     
     
         17 . The sole unit of  claim 15  wherein the stability layer is disposed below the core layer and an outsole layer is disposed below the stability layer. 
     
     
         18 . The sole unit of  claim 1  wherein the sole unit comprises at least one layer serving as a midsole. 
     
     
         19 . The sole unit of  claim 18  wherein the midsole layer comprises a resilient material having a lower durometer than the durometer of the balancing structure. 
     
     
         20 . The sole unit of  claim 19  wherein the balancing structure is formed on a core layer comprising a resilient material having a relatively higher durometer than the midsole layer.