Toe Off Athletic Shoe

This invention relates to athletic footwear for runners, joggers and the like.

As is well known to those familiar with the athletic footwear industry, the increased public interest in participating athletic activities involving running in recent years has stimulated important developments in the age old technology of footwear construction. Although a primary motivation for such participation is improved health, a result of the constantly increasing participation is improved competitive capabilities of the participants. This generates a demand for footwear that will not cause a competitive disadvantage, i.e. will enable the participant to reach full physiological potential, and will minimize physical damage to the body. Optimally, such footwear should enhance the natural biomechanics of the foot, effect motion control and stability, be light in weight, and provide excellent comfort as well as exhibiting footwear durability.

Many structural improvements have been developed and patented previously. However, the inventors herein believe that the shoe of this construction effects a unique combination constituting a further improvement in athletic footwear.

The athletic shoe of the present invention has a novel structure effecting motion control and stability in a highly cushioned, lightweight and physically durable shoe. Although it is believed that runners with minor stability/motion control requirements will benefit most from the novel shoe, others should also find it of significant advantage. The shoe possesses a unique toe off pad midsole feature enabling more efficient forward momentum during toe off in the running gait, plus extra cushioning under the ball of the foot. This allows the metatarsals to align naturally, and balances the forces the foot experiences during toe off. Such is combined with deflection midsole cushioning at the heel area. The outsole possesses integral portions of differing densities, combining durability with comfort. There is a cooperative relationship between transverse flex grooves in the midsole, in the toe off pad portion, and in the forward end of the rear portion, specially located with respect to each other and with respect to vertical flex grooves in the lateral and medial sides of the shoe upper, to achieve a smooth and continuous flex curvature of the shoe with the progressive flexure of the foot during mid-stance and toe off. The midsole also includes an upper layer forming a dual density heel possessing a roll bar wedge with an integrally molded stabilizer cup extending upwardly therefrom.

The result enhances the natural biomechanics of the foot during all phases of the gait cycle.

FIG. 1 is a side elevational view of the lateral side of the novel shoe;

FIG. 2 is a side elevational view of the medial side of the novel shoe;

FIG. 3 is a bottom view of the shoe;

FIG. 4 is a top view of the midsole subassembly;

FIG. 5 is a fragmentary sectional view through the heel portion of the shoe upper and the upper layer of the midsole;

FIG. 6 is a rear elevational view of the shoe;

FIG. 7 is a framentary sectional diagrammatic view through the heel portion of the shoe;

FIG. 8 is a sectional view comparable to FIG. 7 but under load; and

FIG. 9 is a bottom view of the midsole subassembly.

Referring now specifically to the drawings, the complete shoe 10 there depicted comprises the typical elements of a shoe upper 12 which incorporates an inner heel last 14, a midsole subassembly 16, and an outsole subassembly 18. Preferably, an insole (not shown) is also employed on top of the midsole.

Shoe upper 12 includes the usual components stitched and bonded together to encompass the wearer's foot, and provide lacing eyelet strips 20 for conventional laces. This upper includes a plurality of vertical flex grooves or notches 22 on both the lateral side (FIG. 1) of the shoe and the medial side (FIG. 2) of the shoe. These grooves slope upwardly, forwardly and are located just behind transverse grooves or notches in the midsole assembly to cooperate therewith as explained hereinafter. Grooves 22 are formed by cutout portions in the leather toe 24 of the upper, exposing the underlying thin more flexible layer of woven fabric as of nylon.

Outsole subassembly 18 is composed of portions of different densities. Portion 26 extends from the rear end of the shoe forwardly to the higher density portion 28 under the ball of the foot. Portion 26 constitutes an expanded rubber of about 45 durometer, Shore A. Likewise, the front toe portion 30 of the outsole is an expanded rubber of about 45 durometer, Shore A. The intermediate portion 28 beneath the ball of the foot constitutes an expanded rubber of about 65 durometer. The portion 32 at the heel of the outsole constitutes a solid rubber heel plug of about 65 durometer, inserted into a recess in portion 26. Preferably solid rubber wear inserts of about 85 durometer, Shore A are placed on the lateral side of the heel at 34.

A central elongated cutout recess 36 is located in the outsole (FIG. 3), extending from the heel to the portion 28 beneath the ball of the foot. A slight protrusion 40' (FIG. 9) on the bottom of the midsole is shaped like opening 36 to align therewith. This elongated cutout recess enables the midsole to deflect under impact force, downwardly through the outsole, during heel impact while the user is running. The deflection effects cushioning and results in less compaction, to enhance the cushioning properties and durability of the midsole. This deflection is graphically depicted in the sectional views FIGS. 7 and 8. In FIG. 7, the midsole subassembly 16 is depicted relative to outsole portion 26 and opening 36 therein, with only the slight protrusion 40' of the midsole extending into this opening for secure positioning. In FIG. 8 is depicted the effect of force F applied by the runner's heel during impact, to deflect or bend midsole subassembly 16 downwardly into and possibly through opening 36 to ultimately engage the surface run upon, at which time the midsole material is then compressed somewhat. The deflection and subsequent compression effects excellent cushioning. The removal of this portion of the outsole also lowers the weight of the outsole and shoe.

Midsole subassembly 16 is formed of several components bonded into an integral structure. It has a lower layer composed of a rear portion 40 (FIG. 1) and a toe off pad 42. This rear portion 40 extends from the rear of the shoe toward the toe of the shoe but terminates short of the front end of the shoe in a tapered front zone, i.e. downwardly and forwardly to provide a surface which faces upwardly to form a bonded interface 41 to the overlapping bottom rear face formed by an upwardly, rearwardly tapering zone at the rear end of toe off pad portion 42.

Rear portion 40 is formed of compression molded EVA, having a density or hardness of about 35 durometer, Shore A. Toe off pad 42 is also formed of compression molded EVA but having considerably less density and greater compressibility than that of the rear portion of this lower layer of about 25 durometer, Shore A. Thus, the significantly lower durometer enables the user's metatarsals to sink into the toe off pad during the midstance and toe off portions of the gait cycle. It also provides extra cushioning under the ball of the foot because the tapered part of the toe off pad extends rearwardly beneath the ball of the foot. The downwardly, forwardly tapered interface arrangement 41 effects a gradual transition as well as significant area of bonding.

Bonded upon the upper surface of this lower layer is an upper layer 44, elevating the heel of the foot and tapering downwardly forwardly under the instep of the foot to terminate short of the ball of the foot and short of toe off pad 42 (see FIGS. 1 and 4). At the heel of this upper layer, it forms a roll bar wedge of overlying, laterally tapered wedge portions of different density. Wedge portion 50 (FIG. 5) having its thicker edge on the medial side of the shoe is of substantially greater density than overlying wedge portion 52 on the lateral side. Specifically, wedge portion 50 has a density of about 45 durometer while wedge portion 52 is of about 32 durometer. These are compression molded-bonded together integrally at interface 51. Also integral with these wedge portions are upstanding curvilinear wall segments 50a and 52a respectively on the medial and lateral sides of the shoe, with wall 52a also extending around the rear of the shoe in the embodiment depicted, to be integrally joined with wall 50a on the medial side (FIG. 4). These integrally interconnected walls form a stability cup into which the shoe upper 12 (FIG. 5) fits for stabilizing the foot around the heel. The integral structure of this assembly removes the necessity of a separate conventional reinforcing exterior counter. Such a conventional exterior counter requires uncompressible portions extending beneath the foot, with these portions undesirably lessening cushioning.

At the front end of the bottom surface of rear portion 40 of the lower layer are transversely extending flex grooves 60 (FIGS. 4 and 9). Forwardly of these two grooves and in the bottom surface of the toe spring portion 42 is another groove 62. In the top surface of toe spring portion 42 is a series of spaced, transverse flex grooves 64. As will be noted from FIG. 4, all of these grooves 60, 62 and 64 are spaced in sequence and do not coincide with each other, the effect being, especially in combination with medial and lateral grooves 22 in the shoe upper to the rear thereof, the formation of a smooth, parabolic curvature in the shoe as the runner's weight moves from the planted position to the toe off position.

It is conceivable that certain variations may be made in the construction disclosed and described above as the preferred embodiment, yet without departing from the novel concept presented. Therefore, such variations are considered to be within the scope of the invention if encompassed by the scope of the appended claims or are reasonably equivalent thereto.