Athletic shoe with pronation control device

Abstract: A cushioning sole for use in footwear (10), in particular athletic shoes, is disclosed. The cushioning sole includes a pronation control device incorporated into the midsole (12). The device functions to gradually increase the resistance to compression of the midsole (12) from the lateral side to a maximum along the medial side. The device includes generally vertically extending rigid members (42a, 42b) and a plurality of horizontally extending plate members (44a-44e).

Description: The invention relates to footwear, more particularly to athletic shoes, wherein a cushioning sole is provided with a pronation control device to control the pronation motion of a wearer's foot. The sole includes a sole member which is compressible and resilient to thereby cushion foot impact, and the control device increases the resistance to compression of the sole member in the area adjacent the medial side of the sole. BACKGROUND OF THE INVENTION The modern shoe, particularly an athletic shoe, is a combination of many elements which have specific functions, all of which must work together for the support and protection of the foot. Athletic shoes today are as varied in design and purpose as are the rules for the sports in which the shoes are worn. Tennis shoes, racquetball shoes, basketball shoes, running shoes, baseball shoes, football shoes, weightlifting shoes, walking shoes, etc. are all designed to be used in very specific, and very different, ways. They are also designed to provide a unique and specific combination of traction, support and protection to enhance performance. Not only are shoes designed for specific sports, they are also designed to meet the specific characteristics of the user. For example, shoes are designed differently for heavier persons than for lighter persons; differently for wide feet than for narrow feet; differently for high arches than for low arches, etc. Some shoes are designed to correct physical problems, such as over-pronation, while other include devices, such as ankle supports, to prevent physical problems from developing. A shoe is divided into two general parts, an upper and a sole. The upper is designed to snuggly and comfortably enclose the foot, while the sole must provide traction, protection, and a durable wear surface. The considerable forces generated by running require that the sole of a running shoe provide enhanced protection and shock absorption for the foot and leg. It is also desirable to have enhanced protection and shock absorption for the foot and leg in all types of footwear. Accordingly, the sole of a running shoe typically includes several layers, including a resilient, shock absorbing or cushioning layer as a midsole and a ground contacting outer sole or outsole which provides both durability and traction. This is particularly true for training or jogging shoes designed to be used over long distances and over a long period of time. The sole also provides a broad, stable base to support the foot during ground contact. The typical motion of the foot during running proceeds as follows. First, the heel strikes the ground, followed by the ball of the foot. As the heel leaves the ground, the foot rolls forward so that the toes make contact, and finally the entire foot leaves the ground to begin another cycle. During the time, that the foot is in contact with the ground, it typically is rolling from the outside or lateral side to the inside or medial side, a process called pronation. That is, normally, the outside of the heel strikes first and the toes on the inside of the foot leave the ground last. While the foot is air borne and preparing for another cycle the opposite process, called supination, occurs. Pronation, the inward roll of the foot in contact with the ground, although normal, can be a potential source of foot and leg injury, particularly if it is excessive. The use of soft cushioning materials in the midsole of running shoes, while providing protection against impact forces, can encourage instability of the sub-talar joint of the ankle, thereby contributing to the tendency for over-pronation. This instability has been cited as a contributor to "runners knee" and other athletic injuries. Various methods for resisting excessive pronation or instability of the sub-talar joint have been proposed and incorporated into prior art athletic shoes as "stability" devices. In general, these devices have been fashioned by modifying conventional shoe components, such as the heel counter, and by modifying the midsole cushioning materials. For example, one technique incorporates a relatively stiff heel counter support over the heel counter, as shown in U.S. Patent No. 4,288,929. A similar technique, wherein support is provided to a heel counter by a bead of material, is shown in U.S. Patent No. 4,354,318. Another prior art technique to enhance motion control during foot impact is by building up the heel counter itself, such as shown in U.S. Patent Nos. 4,255,877 and 4,287,675. Both U.S. Pat. Nos.4,364,188 and 4,364,189 propose solutions to the problem of over pronation which rely on the use of materials with different compressibilities, the material having the lowest compressibility being arranged on the medial side of the shoe. US 4,364,188 also discloses the use of a plurality of hard cylindrical rubber plugs having a high resistance to compression. These plugs can be inserted by the wearer into vertical bores formed parallel to the peripheral edge of the medial side of the head portion of the midsole in an attempt to reduce over pronation. By increasing the number of plugs inserted, or by using plugs of different resistances to compressibility it is claimed that the wearer can select the degree of resistance to over pronation provided by the shoe. The use of a less compressible or firmer fluid tight chamber in the medial heel area of a sole is disclosed in U.S. Patent Nos. 4,297,797 and 4,445,283. Although these prior art techniques have exhibited a degree of success in controlling sub-talar joint motion and, hence, over-pronation, they have certain disadvantages. Generally, these techniques add to the weight and manufacturing expense of the shoes. Furthermore, the firmer, higher density foam midsole materials are subject to compression set and reduce the efficacy of the cushioning system. The present invention was designed to take advantage of the lightweight cushioning capability of the materials used in current athletic shoes, while enhancing the stability of the shoes without incurring the above disadvantages of prior art "stability" devices. SUMMARY OF THE INVENTION The invention relates to a cushioning sole for use in footwear which includes a pronation control device to control the pronation motion of a wearer's foot. The sole comprises a sole member which extends along at least the heel and arch areas of the sole. The sole member is compressible and resilient to thereby cushion foot impact, and includes a mechanism incorporated into it for increasing the resistance to compression of the sole member in an area adjacent its medial side to thereby control pronation motion. The compression resistance increasing mechanism includes at least one substantially rigid member formed of a substantially non-compressible material and extending vertically through at least a portion of the vertical extent of the sole member. The sole member preferably extends along substantially the entire foot bed and is formed at least partially of a foam material. The compression resistance increasing mechanism preferably includes at least one generally horizontally extending plate which gradually increases the resistance to compression of the sole member from the lateral side to a maximum adjacent the medial side of the sole member. The rigid member is preferably formed as at least two hollow columns spaced longitudinally from one another, and the plate extends between and laterally from adjacent the tops of the columns in a cantilever manner. The plate is preferably formed as a plurality of separate plate members which extend laterally from the medial side to an area past the centerline of the heel area. When the foot of a typical runner initially contacts the ground along the lateral heel area, the material of the sole member compresses to cushion the foot. As the runner's foot begins to roll inward (pronate), the distal ends of the plate members add a degree of resistance to compression of the sole member. As the runner's foot further rolls inwards, portions of the plate members which extend in a cantilever fashion from the medial side of the sole resist compression of the sole member to a greater degree, thereby further stabilizing the foot. Maximum resistance to compression of the sole member and, hence, maximum stabilization of the foot occurs along the medial side of the sole where the vertically extending, non-compressible rigid members are disposed. The use of the pronation control device of the present invention enables soft cushioning materials to be used in footwear soles while retaining sub-talar joint stability. The device functions by increasing the compaction resistance of the medial side of the midsole, thereby resisting pronation, while the more compliant lateral side allows deflection of the lateral portion of the midsole during impact. This controlled deflection reduces the lever arm for the force acting around the sub-talar joint. The device thus effectively reduces calcaneal eversion at foot strike, resulting in increased resistance to pronation of the sub-talar joint and lower velocities of pronation. The biomechanical characteristics of the pronation control device and, hence, the degree of resistance to pronation and high rates of pronation of the sub-talar joint may be varied by changing the number and height of the rigid members of columns, by changing the number, size and spacing of the separate horizontal plate members, and by changing the physical properties of the material forming the rigid member and plate members. The use of a separate device, according to the present invention, for the control of pronation has several advantages over the prior art techniques of adjusting the densities of the cushioning materials. The stability characteristics of the shoe can be varied independently of the materials used for cushioning and is thus not dependent on the characteristics of these materials. Also, since the pronation control device is made of relatively high modulus and high hardness material, the device is not subject to compaction like foam cushioning materials, weighs less, is easier to manufacture, and may be combined with a variety of cushioning materials. Various advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects obtained by its use, reference should be had to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view of an athletic shoe embodying the invention; Figure 2 is a top plan view of the sole of the athletic shoe illustrated in Figure 1, with the pronation control device illustrated in phantom line; Figure 3 is a perspective view of the pronation control device; Figure 4 is a sectional view taken generally along the lines 4-4 of Figure 3; and Figure 5 is a sectional view similar to Figure 4, illustrating an alternate embodiment of a pronation control device in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, wherein like numerals indicate like elements, an article of footwear in accordance with the present invention, such as a running shoe, is generally shown as 10. Shoe 10 includes a sole structure 12 and an upper 14 attached to it. Upper 14 can be of any conventional design, while sole structure 12 incorporates novel features of the present invention. Sole structure 12 includes a cushioning or force absorbing midsole 16 and a flexible, wear resistant outsole 18. Of course, where appropriate, the midsole and outsole portions can be formed as a single integral unit. Shoe 10 and, hence, sole 12 can be generally divided into a heel section 20 rearward of line L1, an arch section 22 between lines L1 and L2, and a forepart section (24) forward of line L2. Lines L1 and L2 are not precise lines of demarkation but rather divide sole 12 into relative sections related generally to portions of the human foot. Line L3 is a centerline of heel section 20, which divides heel section 20 and arch section 22 into a medial half 26 and a lateral half 28. The medial side wall of sole 12 is indicated as 27, while the lateral side wall is indicated as 29. Midsole 16 is formed of a cushioning, resilient foam material, such as a polyurethane foam into which a sealed resilient insert 30 is encapsulated. The perimeter of insert 30 is shown diagrammatically in dashed line in Figure 2. Insert 30 is preferably a gas-filled bladder formed according to the teachings of U.S. Patent Nos. 4,183,156 and 4,219,945 of Marion F. Rudy. Such a gas filled bladder is formed from a flexible material which is sealed along its perimeter and at preselected locations within its perimeter which, after being filled to a relatively high pressure by a gas having a low diffusion rate through the flexible material, takes on a generally flat bladder configuration. The bladder is thereafter encapsulated in the foam material comprising the remainder of the midsole, as disclosed in the '945 patent. Alternatively, insert 30 can be omitted and the entire midsole 16 can be formed of a cushioning foam material. In either case midsole 16 functions as a compressible and resilient unit which cushions foot impact. A pronation control device 40 is incorporated into midsole 16 in heel section 20 and arch section 22. Device 40 is preferably formed of a single integral piece of plastic material, such as a thermoplastic polyester elastomer. The plastic material is relatively hard and substantially non-compressible. The plastic material preferably has a relatively high flex modulus, e.g. preferably 75,000 to 125,000 psi as determined by a standard ASTM test, and a hardness preferably in the range of 65 to 72 Shore D. This is in sharp contrast to the much softer foam material used in a typical midsole, such as midsole 16, which generally has a hardness in the range of 40 to 70 on the Asker C scale. Device 40 functions to gradually increase the resistance to compression of midsole 16 proceeding from a minimum resistance at the lateral side to a maximum resistance at the medial side. Device 40 includes a pair of longitudinally spaced rigid members 42a and 42b and a plurality of separate horizontal plates 44a, 44b, 44c, 44d and 44e. Device 40 is incorporated into midsole 16 with rigid members 42a and 42b disposed adjacent the medial edge of midsole 16 in heel section 20 and arch section 22, and extending generally vertically. In the illustrated embodiment, rigid members 42a and 42b extend vertically substantially from the bottom of midsole 16, to the top of midsole 16, which is illustrated by dashed line 46. If less compaction or compression resistance is desired, the vertical extent of rigid members 42a and 42b can be decreased. Alternatively, if additional resistance to compact ion is desired, an additional number of rigid members can be added along the medial side of sole 12. In order to keep the weight of device 42 to a minimum, rigid members 42a and 42b are preferably formed in the shape of hollow columns having a generally rectangular cross-sectional configuration. Typically the walls of the columns have a thin cross-section or thickness, such as 0.03" to 0.04". As best seen in Figure 2, plate members 44 extend horizontally from the medial side of sole member 12 toward the lateral side of sole member 12 and past the centerline L3 of heel section 20. As best seen in Figures 3 and 4, plate members 44a and 44e extend from rigid members 42a and 42b respectively and are connected to the rigid members through downwardly extending curved sections 46a and 46e. While plate members 44b, 44c and 44d are separate or independent plate members, they are interconnected along a common base 48. To further reduce the weight and material costs of device 40, each plate member 44 has a centrally disposed gap 50. Plate members 44a through 44e thus extend horizontally in a cantilever manner from the medial side of sole 12. That is, plate members 44a and 44e extend laterally from the top of rigid members 42a and 42b, respectively, and plate members 44b, 44c and 44d extend laterally from base 48. All plate members 44 extend along an area adjacent the top of midsole 16. Plate members 44 have a perimeter which tapers from a broadest area adjacent the medial side of sole 12 to a rounded point at their distal ends on the lateral side. Plate members 44 thus take on a finger or comb-like configuration. The tapering shape and cantilever extension of plate members 44 function to provide gradually increasing resistance to compression of sole member 12 disposed below the plate members. That is, along the distal ends of plate members 44, the plate members bend more easily and, hence, provide less resistance to compression. However, the portions of plate members 44 which are closer to their cantilever connection along the medial edge are more difficult to bend and provide increased resistance to compression. Maximum resistance to compression is reached along the medial edge of sole 12 where the rigid members 42a and 42b are located. Figure 5 illustrates an alternate embodiment of a device 40' wherein rigid members 42 are again formed as hollow columns. However, the hollow columns include a spring or flex section 54 which allows the columns to compress vertically a limited degree. Spring section 54 is formed as a bent out section of the column which extends horizontally around the perimeter of the hollow column, thereby forming a bendable flex line. Device 40' is used when it is desirable to vary the compliance of the columns without relying on the use of foams or adjusting the modulus of the columns. Numerous characteristics, advantages, and embodiments of the invention have been described in detail in the foregoing description with reference to the accompanying drawings. However, the disclosure is illustrative only and the invention is not limited to the precise illustrated embodiments. Various changes and modifications may be effected therein by one skilled in the art without departing from the scope and spirit of the invention. For example, while the plate members are illustrated as a plurality of separate figure like elements, the plate members can be formed as a single integral plate. Similarly, while two rigid members are illustrated, where appropriate a single rigid member, or more than two rigid members can be used.

Claims: A cushioning sole for use in footwear with a pronation control device to control the pronation motion of a wearer's foot comprising: a sole member (12) extending along at least the medial heel (20) and medial arch (22) areas of the cushioning sole, said sole member being compressible and resilient for cushioning foot impact; and means (40), incorporated into said sole member, for gradually increasing the resistance to compression of said sole from its lateral side to a maximum adjacent its medial side to control pronation motion, said gradual compression resistance increasing means including: a substantially rigid member (42) formed of substantially non-compressible material, disposed substantially within said sole member and extending vertically through at least a portion of a vertical extent of said sole; and a plate (44) extending in a cantilever manner from said substantially rigid member toward the lateral side of said sole, wherein said plate includes a plurality of separate plate members (44a-44e). A cushioning sole in accordance with claim 1, wherein a gap (50) is formed in said plate members. A cushioning sole in accordance with claim 1, wherein some of said plate members have medial ends connected to one another and have perimeters gradually tapering from the respective medial ends. A cushioning sole in accordance with claim 1, wherein said rigid member is formed in the shape of a column. A cushioning sole as claimed in claim 1 with at least one substantially rigid member formed of substantially non-compressible material and extending vertically through at least a portion of a vertical extent of said sole member, and at least one plate extending in a cantilever manner from said at least one rigid member toward the lateral side of said sole member, wherein at least one of said plate members (44a, 44e) extends toward the lateral side of said sole member past a centre line of a heel section. A cushioning sole as claimed in claim 1 comprising: at least one substantially rigid member formed of substantially non-compressible material and extending vertically through at least a portion of a vertical extent of said sole member, and at least one plate extending in a cantilever manner from said at least one rigid member toward the lateral side of said sole member, wherein at least one of said plate members is connected to said at least one rigid member through a downwardly extending substantially curved section(46a, 46e). A cushioning sole as claimed in any one of claims 1 to 6, wherein said vertically extending substantially rigid member (42) extends substantially from a bottom of said sole member (12) to a top of said sole member. A cushioning sole as claimed in any one of claims 1 to 6, wherein said sole member (12) is formed at least partially of a foam material. A cushioning sole as claimed in any one of claims 1 to 6 wherein said sole member (12) is formed substantially completely of said foam material. A cushioning sole as claimed in any one of claims 1 to 6 wherein said sole member (12) includes an insert (30) formed of a gas filled flexible bladder. A cushioning sole as claimed in claim 1 to 6 wherein said rigid member (42) is formed in the shape of a column. A cushioning sole as claimed in claim 11, wherein said column (42) is hollow. A cushioning sole as claimed in claim 12, wherein said hollow column (42) includes a spring section (54) for allowing a limited degree of vertical deflection of said hollow column. A cushioning sole as claimed in any one of claims 11 to 13, wherein said column (42) is formed of a relatively hard plastic. A cushioning sole as claimed in claim 14, wherein said plastic has a Shore D hardness of at least 65. A cushioning sole as claimed in any one of claims 1 to 15, wherein said at least one plate (44) extends from adjacent the top of said at least one rigid member (42) and along an area adjacent the top of said sole member (12). A cushioning sole as claimed in claim 1 or 6, wherein said at least one plate (44) extends past the centreline of the heel area (20) of said sole member (12). A cushioning sole as claimed in any one of claims 1 to 6, wherein said at least one plate (44) extends to an area adjacent the lateral side of said sole member (12). A cushioning sole as claimed in claim 5 or 6, wherein said at least one plate (44) is formed as a plurality of separate plate members (44a-44e). A cushioning sole as claimed in claim 5 or 6, wherein at least some of said plate members (44a-44e) have medial ends connected to one another and have perimeters gradually tapering from the respective medial ends. A cushioning sole as claimed in claim 5 or 6, wherein a gap (50) is formed in the or each plate member (44a-44e). A cushioning sole as claimed in any one of claims 1 to 6, wherein said gradual compression resistance increasing means (40) includes at least two of said rigid members (42a, 42b) spaced longitudinally from one another and said at least one plate (44) extends in a cantilever manner between and from said at least two rigid members toward the lateral side of said sole member (12). A cushioning sole as claimed in any of claims 1 to 6, wherein said members (42a, 42b) and said plate (44) are formed of a single integral piece of plastic. A cushioning sole as claimed in any of claims 1 to 6, wherein said plate (44) extending in a cantilever manner has a proximate end portion which is close to said substantially rigid members and a distal end portion, and said proximate end portion of said plate is more difficult to bend and provides increased resistance to compression relative to the distal end portion of said plate. A cushioning sole as claimed in claim 1 or 5, wherein at least some of said plate members (44a, 44e) are connected to said rigid members (42a, 42b) by downwardly curved sections (46a, 46e) of the respective plate members. A cushioning sole as claimed in claim 5 or 6, wherein footwear having an upper (14) and a cushioning sole in accordance with any preceding claim, attached to said upper. Footwear having an upper and a cushioning sole in accordance with any one of claims 1 to 26 attached to said upper.

Inventors: KILGORE BRUCE J, SHORTEN MARTYN ROBERT, KILGORE, BRUCE J., SHORTEN, MARTYN ROBERT
Applicants: NIKE INTERNATIONAL LTD
Application year: 1988
Main classification: A43B13
IPC codes: A43B13, A43B5, A43B7