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.

Abstract: Footwear having an improved cushioning sole structure is disclosed. The footwear includes an upper and a sole member attached to the upper. The sole member includes a sealed inner member of a flexible material which is inflated with a gaseous medium to form a compliant and resilient insert. An elastomeric yieldable outer member encapsulates the insert about preselected portions of the insert. The inner and outer members function together to form a viscoelastic unit for attenuating the shock and returning the energy of foot impact. A mechanism adjusts the impact response of the unit so that the effect of the insert dominates the impact response function in a predetermined area adjacent at least one side of the insert. The adjusting mechanism includes a gap in the outer member along the side of the insert adjacent the predetermined area so that the flexible material of the sealed inner member can flex in the gap during foot impact.