Reactive shoe

Abstract

This invention relates generally to footwear and methods for making the same, and more particularly to an athletic shoe with a reactive midsole. In one aspect of the invention, the midsole provides a continuously increasing offset between a heel center of pressure and a ball-of-foot center of pressure between the loading and a toe off gait phases.

What is claimed is: 
     
         1 . An article of footwear comprising:
 an upper attachable to a foot of a user; and   a midsole connected to the upper comprising a first portion proximate a heel of the foot and a second portion proximate a ball-of-foot of the foot, the heel of the foot having a heel center of pressure imparted to the first portion and defining a first distance between the heel center of pressure and the ground, and a ball-of-foot center of pressure imparted to the second portion and defining a second distance between the ball-of-foot center of pressure and the ground, wherein a distance offset of the first distance minus the second distance is increased between a loading gait phase and a toe off gait phase.   
     
     
         2 . The article of footwear of  claim 1 , wherein the first portion is generally of constant thickness and the second portion is generally of decreasing thickness along a longitudinal axis of the midsole from the heel to the ball-of-foot. 
     
     
         3 . The article of footwear of  claim 2 , wherein the first portion is 30-50% of a total distance of the longitudinal axis of the midsole. 
     
     
         4 . The article of footwear of  claim 3 , wherein the first portion is interconnected to the second portion. 
     
     
         5 . The article of footwear of  claim 2 , wherein the decreasing thickness generally forms a French curve. 
     
     
         6 . The article of footwear of  claim 1 , wherein the distance offset is always positive between the loading gait phase and the toe off gait phase. 
     
     
         7 . The article of footwear of  claim 1 , wherein the distance offset at the toe off gait phase is at least 40 mm. 
     
     
         8 . The article of footwear of  claim 1 , wherein the distance offset of the first distance minus the second distance is continuously increased between the loading gait phase and the toe off gait phase. 
     
     
         9 . The article of footwear of  claim 1 , wherein a foot center of pressure imparted to the midsole continuously increases between the loading gait phase and the toe off gait phase. 
     
     
         10 . A method of manufacturing an article of footwear comprising:
 forming an upper attachable to a foot of a user; and   forming a midsole connected to the upper comprising a first portion proximate a heel of the foot and a second portion proximate a ball-of-foot of the foot, the heel of the foot having a heel center of pressure imparted to the first portion and defining a first distance between the heel center of pressure and the ground, and a ball-of-foot center of pressure imparted to the second portion and defining a second distance between the ball-of-foot center of pressure and the ground, wherein a distance offset of the first distance minus the second distance is increased between a loading gait phase and a toe off gait phase.   
     
     
         11 . The method of  claim 10 , wherein the first portion is generally of constant thickness and the second portion is generally of decreasing thickness along a longitudinal axis of the midsole from the heel to the ball-of-foot. 
     
     
         12 . The method of  claim 10 , wherein the first portion is 30-50% of a total distance of the longitudinal axis of the midsole and the first portion is interconnected to the second portion. 
     
     
         13 . The method of  claim 10 , wherein the distance offset is always positive between the loading gait phase and the toe off gait phase. 
     
     
         14 . The method of  claim 10 , wherein the distance offset at the toe off gait phase is at least 40 mm. 
     
     
         15 . The method of  claim 10 , wherein the distance offset of the first distance minus the second distance is continuously increased between the loading gait phase and the toe off gait phase. 
     
     
         16 . The method of  claim 10 , wherein a foot center of pressure imparted to the midsole continuously increases between the loading gait phase and the toe off gait phase. 
     
     
         17 . The method of  claim 10 , wherein the midsole is manufactured using injection molding. 
     
     
         18 . An athletic shoe, comprising:
 an upper attachable to a foot of a user; and   a midsole connected to the upper comprising a first portion generally of constant thickness proximate a heel of the foot and a second portion generally of decreasing thickness along a longitudinal axis of the midsole from the heel to the ball-of-foot and proximate a ball-of-foot of the foot, the first portion 30-50% of a total distance of the longitudinal axis of the midsole and interconnected to the second portion, the heel of the foot having a heel center of pressure imparted to the first portion and defining a first distance between the heel center of pressure and the ground, and a ball-of-foot center of pressure imparted to the second portion and defining a second distance between the ball-of-foot center of pressure and the ground, wherein a distance offset of the first distance minus the second distance is continuously increased between a loading gait phase and a toe off gait phase and is always positive between the loading gait phase and the toe off gait phase.   
     
     
         19 . The article of footwear of  claim 18 , wherein a foot center of pressure imparted to the midsole continuously increases between the loading gait phase and the toe off gait phase. 
     
     
         20 . The article of footwear of  claim 18 , wherein the distance offset at the toe off gait phase is at least 40 mm. 
     
     
         21 . An article of footwear comprising:
 an upper attachable to a foot of a user;   a midsole connected to the upper comprising a first portion proximate a heel of the foot and a second portion proximate a ball-of-foot of the foot; and   an outsole connected to the midsole comprising a central portion, a medial portion and a lateral portion, the medial portion and the lateral portion forming a substantially non-smooth surface, the central portion forming a substantially smooth surface with a curvilinear edge.   
     
     
         22 . The article of footwear of  claim 21 , wherein the heel of the foot having a heel center of pressure imparted to the first portion and defining a first distance between the heel center of pressure and the ground, and a ball-of-foot center of pressure imparted to the second portion and defining a second distance between the ball-of-foot center of pressure and the ground, wherein a distance offset of the first distance minus the second distance is increased between a loading gait phase and a toe off gait phase. 
     
     
         23 . The article of footwear of  claim 21 , wherein the central portion is of a first material and the medial and lateral portions are of a second material. 
     
     
         24 . The article of footwear of  claim 21 , wherein the central portion extends over and is integral to at least one of a toe portion and a heel portion of the article of footwear.