Articles of Footwear

Abstract

An article of footwear including a footwear upper and a sole assembly secured to the footwear upper. The sole assembly has a forefoot portion and a heel portion, and includes an outsole, a midsole disposed on the outsole and an instability insert disposed between the outsole and the midsole in the forefoot portion of the sole assembly. The instability insert causes a forefoot protrusion to be defined by the outsole in the forefoot portion of the sole assembly.

1 . An article of footwear comprising:
 a footwear upper; and   a sole assembly secured to the footwear upper, the sole assembly having a forefoot portion and a heel portion, the sole assembly comprising:
 an outsole; 
 a midsole disposed on the outsole; and 
 an instability insert disposed between the outsole and the midsole in the forefoot portion of the sole assembly, the instability insert causing a forefoot protrusion to be defined by the outsole in the forefoot portion of the sole assembly. 
   
     
     
         2 . The article of footwear of  claim 1 , wherein the forefoot portion of the outsole defines a radius of curvature of between about 130 mm and about 190 mm. 
     
     
         3 . The article of footwear of  claim 2 , wherein the forefoot portion of the outsole defines a radius of curvature of about 160 mm. 
     
     
         4 . The article of footwear of  claim 1 , wherein the forefoot protrusion has a height, measured from a lowest point of the protrusion to an outer edge of the outsole, of between about 4 mm and about 12 mm. 
     
     
         5 . The article of footwear of  claim 4 , wherein the forefoot protrusion has a height, measured from a lowest point of the protrusion to an outer edge of the outsole, of about 8 mm. 
     
     
         6 . The article of footwear of  claim 1 , wherein the instability insert defines a substantially elliptical shape in top and side views. 
     
     
         7 . The article of footwear of  claim 1 , wherein the instability insert has a thickness of between about 3 mm and about 9 mm, a length of between about 65 mm and about 85 mm, and a width of between about 45 mm and about 55 mm. 
     
     
         8 . The article of footwear of  claim 7 , wherein the instability insert has a thickness of about 6 mm, a length of about 76 mm, and a width of about 50 mm. 
     
     
         9 . The article of footwear of  claim 1 , wherein the instability insert comprises polyurethane. 
     
     
         10 . The article of footwear of  claim 1 , wherein the instability insert has a durometer of between about 15 Asker C and about 20 Asker C. 
     
     
         11 . The article of footwear of  claim 1 , further comprising a heel insert disposed substantially between the outsole and the midsole in the heel portion of the sole assembly, the heel insert configured to collapse under a user's weight. 
     
     
         12 . The article of footwear of  claim 11 , wherein the heel insert comprises at least one of polyurethane and a ethylene-vinyl-acetate copolymer (EVA). 
     
     
         13 . The article of footwear of  claim 12 , wherein the heel insert has a durometer of between about 42 Asker C and about 48 Asker C. 
     
     
         14 . The article of footwear of  claim 11 , wherein the heel insert has a thickness of between about 10 mm and about 35 mm. 
     
     
         15 . An article of footwear comprising:
 a footwear upper; and   a sole assembly secured to the footwear upper, the sole assembly having a forefoot portion and a heel portion;   wherein the forefoot portion of the sole assembly is configured to provide a first period of instability upon receiving the weight of a user followed by a second period of stability.   
     
     
         16 . The article of footwear of  claim 15 , wherein the heel portion is configured to at least partially collapse upon receiving the weight of a user and cause the user to rotate the sole assembly forward, placing the weight of the user on the forefoot portion of the sole assembly. 
     
     
         17 . The article of footwear of  claim 15 , the sole assembly comprises:
 an outsole;   a midsole disposed on the outsole; and   an instability insert disposed between the outsole and the midsole in the forefoot portion of the sole assembly, the instability insert causing a forefoot protrusion to be defined by the outsole in the forefoot portion of the sole assembly.   
     
     
         18 . The article of footwear of  claim 17 , wherein the forefoot portion of the outsole defines a radius of curvature of between about 130 mm and about 190 mm. 
     
     
         19 . The article of footwear of  claim 18 , wherein the forefoot portion of the outsole defines a radius of curvature of about 160 mm. 
     
     
         20 . The article of footwear of  claim 17 , wherein the instability insert has a thickness of between about 3 mm and about 9 mm, a length of between about 65 mm and about 85 mm, and a width of between about 45 mm and about 55 mm. 
     
     
         21 . The article of footwear of  claim 20 , wherein the instability insert has a thickness of about 6 mm, a length of about 76 mm, and a width of about 50 mm. 
     
     
         22 . The article of footwear of  claim 17 , wherein the instability insert comprises polyurethane. 
     
     
         23 . The article of footwear of  claim 17 , wherein the instability insert has a durometer of between about 15 Asker C and about 20 Asker C. 
     
     
         24 . The article of footwear of  claim 15 , further comprising a heel insert disposed substantially between the outsole and the midsole in the heel portion of the sole assembly, the heel insert configured to collapse under a user's weight. 
     
     
         25 . The article of footwear of  claim 24 , wherein the heel insert comprises at least one of polyurethane and a ethylene-vinyl-acetate copolymer (EVA). 
     
     
         26 . The article of footwear of  claim 24 , wherein the heel insert has a durometer of between about 42 Asker C and about 48 Asker C.