Abstract: An athletic shoe has a sole with a rearfoot strike zone segmented from the remaining heel area by a line of flexion which permits articulation of the strike zone during initial heel strike of a runner. The line of flexion is located to delimit a rearfoot strike zone reflecting the heel to toe running style of the majority of the running population. In addition to allowing articulation of the rearfoot strike zone about the line of flexion, the sole incorporates cushioning elements, including a resilient gas filled bladder, to provide differential cushioning characteristics in different parts of the heel, to attenuate force applications and shock associated with heel strike, without degrading footwear stability during subsequent phases of the running cycle. The line of flexion may be formed by various means including a deep groove, a line of relatively flexible midsole material, and a relatively flexible portion of a segmented fluid bladder.

Abstract: An athletic shoe has a sole with a rearfoot strike zone segmented from the remaining heel area by a line of flexion which permits articulation of the strike zone during initial heel strike of a runner. The line of flexion is located to delimit a rearfoot strike zone reflecting the heel to toe running style of the majority of the running population. In addition to allowing articulation of the rearfoot strike zone about the line of flexion, the sole incorporates cushioning elements, including a resilient gas filled bladder, to provide differential cushioning characteristics in different parts of the heel, to attenuate force applications and shock associated with heel strike, without degrading footwear stability during subsequent phases of the running cycle. The line of flexion may be formed by various ways including a deep groove, a line of relatively flexible midsole material, and a relatively flexible portion of a segmented fluid bladder.

Abstract: An athletic shoe has a sole with a rearfoot strike zone segmented from the remaining heel area by a line of flexion which permits articulation of the strike zone during initial heel strike of a runner. The line of flexion is located to delimit a rearfoot strike zone reflecting the heel to toe running style of the majority of the running population. In addition to allowing articulation of the rearfoot strike zone about the line of flexion, the sole incorporates cushioning elements, including a resilient gas filled bladder, to provide differential cushioning characteristics in different parts of the heel, to attenuate force applications and shock associated with heel strike, without degrading footwear stability during subsequent phases of the running cycle. The line of flexion may be formed by various means including a deep groove, a line of relatively flexible midsole material, and a relatively flexible portion of a segmented fluid bladder.