Shoe construction

Abstract

An article of footwear having an upper ( 10 ) with a rear portion ( 14 ) flexible enough to allow the rear part of the sole ( 16 ) to lie flat under the heel of the foot during the walking stride, and flexible enough to permit unimpeded hindfoot inversion; a level sole ( 16 ); an insole ( 20 ) with a gripping material ( 18 ) bonded to its upper surface; and a midsole ( 22 ) that provides shock absorption for the heel and forefoot without springiness. Full range of motion of the foot, balance of the foot and body, and proprioceptive and tactile sensitivity of the foot are achieved.

1 . A shoe for use on hard outdoor surfaces comprising an upper portion and a sole portion; 
 said upper portion having, in the portion thereof covering the hindfoot, sufficient flexibility to deform in response to the upward ground reaction force transmitted through the sole in the initial contact period of the walking gait cycle, and sufficient flexibility to deform in response to the motions of the hindfoot during hindfoot inversion;    said sole portion being of substantially equal thickness throughout its length and lying substantially flat along its entire length when not subjected to bending forces, and comprising an insole portion, a midsole portion and an outsole portion;    said insole portion having sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle, and having substantially its entire upper surface a coefficient of friction sufficiently low to allow the toes to slide across it during the heel rise and opposite initial contact periods of the walking gait cycle, and sufficiently high to restrain the toes from sliding across it during the toe-off period;    said midsole portion comprising a front portion extending from the front of the shoe to a point between the ball of the foot and the front of the heel, and a rear portion extending from the back of the front portion to the back of the shoe;    said front portion being composed of a material with sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle, and with a level of resilience such as to provide shock absorption for the forefoot upon forefoot contact without springiness;    said rear portion being composed of a material with a level of resilience such as to provide shock absorption for the heel of the foot upon heel strike without springiness;    said outsole portion composed of a material with sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle,    whereby the foot is able to assume the neutral position when not actively flexing, is able to move through its entire range of motion when striding, and is able to experience proprioceptive and tactile sensitivity comparable to an unshod foot.    
     
     
         2 . The shoe for use on hard outdoor surfaces as in  claim 1 , wherein the upper surface of the insole is treated to have the selected coefficient of friction.  
     
     
         3 . The shoe for use on hard outdoor surfaces as in  claim 1 , wherein the insole is composed of a material having the selected coefficient of friction.  
     
     
         4 . The shoe for use on hard outdoor surfaces as in  claim 1 , wherein the front portion of the midsole is composed of ethylene vinyl acetate with a Shore A hardness of approximately 35.  
     
     
         5 . The shoe for use on hard outdoor surfaces as in  claim 1 , wherein the rear portion of the midsole is composed of ethylene vinyl acetate with a Shore A hardness of approximately 45.  
     
     
         6 . (canceled)  
     
     
         7 . A shoe for use on hard outdoor surfaces comprising an upper portion and a sole portion; 
 said upper portion having, in the portion thereof covering the hindfoot, sufficient flexibility to deform in response to the upward ground-reaction force transmitted through the sole in the initial contact period of the walking gait cycle, and sufficient flexibility to deform in response to the motions of the hindfoot during hindfoot inversion;    said sole portion being of substantially equal thickness throughout its length and lying substantially flat along its entire length when not subjected to bending forces, and comprising an insole portion, a midsole portion and an outsole portion;    said insole portion having sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle;    said midsole portion comprising a front portion extending from the front of the shoe to a point between the ball of the foot and the front of the heel, and a rear portion extending from the back of the front portion to the back of the shoe;    said front portion being composed of a material with sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle, and with a level of resilience such as to provide shock absorption for the forefoot upon forefoot contact without springiness;    said rear portion being composed of a material with a level of resilience such as to provide shock absorption for the heel of the foot upon heel strike without springiness;    said outsole portion composed of a material with sufficient flexibility to bend at an angle of approximately 60° under the forces exerted by the foot from the heel rise to the toe-off periods of the walking gait cycle.    
     
     
         8 . The shoe for use on hard outdoor surfaces as in  claim 7 , wherein the front portion of the midsole is composed of ethylene vinyl acetate with a Shore A hardness of approximately 35.  
     
     
         9 . The shoe for use on hard outdoor surfaces as in  claim 7 , wherein the rear portion of the midsole is composed of ethylene vinyl acetate with a Shore A hardness of approximately 45.  
     
     
         10 . (canceled)