CA1341350C - Shoe with naturally contoured sole - Google Patents

Abstract

A construction for a shoe, particularly an athletic shoe such as a running shoe, includes a sole that conforms to the natural shape of the foot, particularly the sides, and that has a constant thickness in frontal plane cross sections. The thickness of the shoe sole side contour equals and therefore varies exactly as the thickness of the load-bearing sole portion varies due to heel lift, for example. Thus, the outer contour of the edge portion of the sole has at least a portion which lies along a theoretically ideal stability plane for providing natural stability arid efficient motion of the shoe and foot particularly in an inverted and everted mode. In a more conventional embodiment, wherein the side contours of the shoe sole are formed by variations in the bottom surface alone, the edge portion of the sole is contoured and defined by an arc of a circle having a radius equal to the thickness of the sole portion of the sole and its center at a point lying on the plane of the upper surface of the sole thickness.

Description

SHOE WITH NATURALLY CONTOURED SOLE
Background of the Invention This invention relates to a shoe or other foot-wear, such as a street shoe, athletic shoe, and especially a running shoe with a contoured sole. More particularly, this invention relates to a novel contoured sole design for a shoe which improves the inherent stability and efficient motion of the load-bearing shod foot in extreme lateral motion. Still more particularly, t:hia invention relates to a shoe wherein the shoe sole has an upper, foot sole-contacting surface that conforms to the natural shape of the foot, particularly the curved sides. Finally, this invention relates to a shoe sole with the load-bearing portions having a constant thickness when measured in frontal plane cross sections, so that the lower, ground-contacting surface parallels the upper, foot-contacting surface permitting the foot to react naturally with the ground as it would if the foot were bare, while continuing to protect and cushion the foot.
By way of introduction, barefoot populations universally have a very low incidence of running "overuse" injuries, despite very high activity levels. In contrast, such injU,ries are very common in shoe shod populations, even for activity levels well below "overuse". Thus, it is a continuing problem with a shod population to reduce or eliminate such injuries and to improve the cushioning and protection for the foot. It is primarily to an understanding of the reasons for such problems and t:o proposing a novel solution according t:o the invention to which this improved shoe is directed.
A wide variety of designs are available for running shoes which are intended to provide stability, but which lead to a constraint in the natural efficient motion of the foot and ankle.
However, such designs which can accommodate free, flexible motion in contrast create a lack of control or stability. A popular existing shoe design incorporates an inverted, outwardly-flared shoe sole wherein the ground engaging surface is wider than the heel engaging portion. However, such shoes are unstalble in extreme situations because the shoe sole, when inverted or on edge, immediately becomes supported only by the sharp bottom sole edge where the entire weight of the body, multiplied by a factor of approximately three at running peak, is concentrated. Since an unnatural lever arm and force moment are created under such conditions, the foot and ankle are destabilized and, in the extreme, beyond a certain point of rotation about the pivot point of the shoe sole edge, forcibly cause ankle strain. In contrast, the unshod foot is always in stable equilibrium without a comparable lever arm or force moment and, at its maximum range of inversion motion, about 20°, the base of support on the barefoot heel actually broadens substantially as the calcaneal tuberosity contacts the ground. This is in contrast to the conventionally available shoe sole bottom which maintains a sharp, unstable edge.
Existing running shoes interfere with natural foot and ankle bi.omechanics, disrupting natural stability and efficient natural motion. They do so by altering the natural position of the foot relative to the ground, during the load-bearing phase of running or walking. The foot in its natural, bare: state is in direct contact with the ground, so its relative distance from the ground is obviously constant at zero. Even when the foot tilts naturally from side to side, either moderately when running or extremely when stumbling or tripping, the distance always remains constant at zero.
In contrast, existing shoes maintain a constant distance from the ground - the thickness of the shoe sole - only when they are perfectly flat on the ground. As soon as the shoe is tilted, the distance between foot and ground begins to change unnaturally, as the shoe sole pivots around the outside corner edge. With conventional athletic shoes, the distance most typically increases at first due to the flared sides and then decreases; many street shoes with relatively wide heel width follow that pattern, though some with narrower heels only decrease. All existing shoes continue to decrease the distance all the way down to zero, by tilting through 90 degrees, resulting in ankle sprains and breaks.
A corrected shoe sole design, however, avoids such unnatural interference by neutrally maintaining a constant distance between foot and ground, even when the shoe is ti:Lted sideways, as if in effect the shoe sole were not there except t.o cushion and protect. Unlike existing shoes, the corrected shoe would move with the foot's natural sideways pronation and supination motion on the ground. To the problem of using a shoe sole t.o maintain a naturally constant distance during that sideways motion, there axe two possible geometric solutions, depending upon whether just the lower horizontal plane of the shoe sole surface varies to achieve natural contour or both upper and lower surface planes vary.
In the two plane solution, the naturally contoured design, (which will be described in detail) both upper and lower surfaces or planes of the shoe sole vary to conform to the natural contour of the human foot. The two plane solution is the most fundamental concept and naturally most effective. It is the only pure geometric solution to the mathematical. problem of maintaining constant distance between foot and ground, and the most optimal, in the same sense i:hat round is only shape for a wheel and perfectly round is most optimal. On the other. hand, it is the least similar to existing designs of the two possible solutions and requires computer aided design and injection molding manufacturing techniques.
In the more conventional one plane solution, the quadrant contour side design, which will be described in Figures 29-:37, the side contours are formed by variations in the bottom surface alone.
The upper surface or plane of the shoe sole remains unvaryingly flat in frontal plane cross sections, like most existing shoes, while the plane of the bottom shoe sole varies on the sides to provide a contour that preserves natural foot and ankle biomechanics. Though less optimal than the two plane solution, the one plane quadrant contour side design is still thE~ only optimal single plane solution to the problem of avoiding disruption of natural human biomechanics. The one plane solution is the closest to existing shoe sole design, and therefore the easiest and cheapest to manufacture with existing equipment. Since it is more conventional in appearance than the two plane solution, but less biomechanically effective, the one plane quadrant contour side design is preferable for dress or street shoes and for light exercise, like casual walking.
CA-A-1 176 458 shows footwear with an outsole, particularly constructed for anti-skid characteristics on <an ice surface, with a contoured side portion that does not maintain the same thickness as the underneath sole portion, when measured in frontal plane cross sections.
It is thus an overall objective of this invention to provide a novel shoe design which approximates the :barefoot.. It has been discovered, by investigating the most. extreme range of ankle motion to near the point of ankle sprain, that the abnormal motion of an inversion ankle sprain, which is a tilting to the outside or an outward rotation of the foot, is accurately simulated while stationary. With th-ws observation, it can be aeen that the extreme range stability of the conventionally shod foot is distinctly inferior to the barefoot and that the shoe itself creates a gross instabilit~~ which would otherwise not. exist.

Even more important, a normal barefoot running motion, which approximately includes a 7° inversion and a 7° eversion motion, does not occur with shod feet, where a 30° inversion and eversion is common. Such a normal barefoot motion is geometrically unattainable because the average running shoe heel is approximately 600 larger than the width of the human heel. As a result, the shoe heel and the human heel cannot pivot together in a natural manner;
rather, the human heel has to pivot within the shoe but is resisted from doing so by the shoe heel counter, motion control devices, and the lacing and binding of the shoe upper, as well as various types of anatomical supports interior to the shoe.
Thus, it is an overall objective to provide an improved shoe design which is not based on the inherent contradiction present in current shoe designs which make the goal~> of stability and efficient natural motion incompatible and even mutually exclusive. It is another overall object of the invention to provide a new contour design which simulates the natural barefoot motion in running and thus avoids the inherent contradictions in current designs.
It is another objective of this invention to provide a running shoe which overcomes the problem of the prior art.
It is another objective of this invention to provide a shoe wherein the outer extent of the flat portion of the sole of the shoe includes all of the support structures of the foot but which extends no further than the outer edge of the flat portion of the foot sole so that the horizontal plane outline of the top of the flat portion of the shoe sole coincides as nearly as possible with the load-xrearing portion of the foot sole.

It is another objective of the invention to provide a shoe having a sole which includes a side contoured like the natural form of the side or edge of the human foot and conforming to it.
It is another objective of this invention to provide a novel shoe structure in which the contoured sole includes a shoe sole thickness that i;a precisely constant in both side portions and contoured portions, when measured in frontal plane cross sections, and therefore biomechani<:ally neutral, even if the shoe sole is tilted to either side, or forward or backward.
It is another objective of this invention to provide a shoe having a sale fully contoured like and conforming to the natural form of the non-load-bearing human foot and deforming under load by flattening just as the foot does.
It is still another objective of this invention to provide a new stable shpe design wherein the heel lift or wedge increases in the sagittal plane the thickness of the shoe sole or toe taper decrease therewith so that the sides of the shoe sole which naturally conform to the sides of the foot also increase or decrease by exactly the same amount, so that the thickness of the shoe sole in a frontal planar cross section is always constant.
It is another objective of this invention. to provide a shoe having a shoe having a naturally contoured design as described wherein the sides of the shoe are abbreviated to essential structural support and propulsion elements to provide flexibility and in which the density of the shoe sole may be increa>ed to compensate for increased loading.
It is another objective of this invention to provide a shoe sole design which includes a plurality of freely articulating essential structural support elements in the sole of i:he shoe which are consistent with the sole of the foot and are free to move independently of each other to follow the motion of the freely articulating bone structures of the foot.
It is still another object of this invention to provide a shoe of the type described wherein the material of the sole is removed except beneath essential structural support elements of the foot.
It is another object of this invention to provide a shoe of the type described with treads having an outer or a base surface which follows the theoretically ideal stability plance.
It is yet another overall object of this invention to provide a shoe construction having a design defined by the natural shape of an unloaded foot and which deforms upon loading to approximate at least the theoretically ideal stabilii~y p7.ane.
It is still another object of this invention to provide a shoe construction wherein a plot of the range of inversion and eversion motion defines a curve with substantially no vertical component variation over a range of at least 40 degree.
It is still another object of this invention to provide a shoe having a sole edge surface which terminates in a laterally extending portion made from a flexible material and :>tructured to terminate upon loading in a position which approximates or is in parallel with the theoretically ideal stability plans.
It is yet another object of this invention to provide a shoe with a plurality of frontal plane slits located at predetermined locations in said shoe sole.
It is still another objective of this invention to provide a correct method o~f measuring the thickness of shoe sole contours.

It is another objective of the invention to provide a shoe having a sole which includes a rounded sole edge contoured like the natural form of the side or edge of the human foot but in a geometrically precise manner so that the shoe sole thickness is precisely constant, even if the shoe sole is tilted to either side, or forward or backward.
It is another objective of this invention to provide a novel shoe structure in which the contoured sole includes at its outer edge portions a contoured surface described by a radius equal to the thickness of the shoe sole with a center of rotation at the outer edge of the top of the shoe sole.
It is another objective of this invention to provide a sole structure of the type described which includes at least portions of outer edge quadrants wherein the outer edge of each quadrant coincide with the horizontal plane of the top of the sole while the other edge is perpendicular to it.
It is still another object of this invention to provide a shoe scle of the type described wherein the bottom or outer sole of the shoe includes most or all of the special contours of the new design, while other portions of the shoe such as the midsole and heel lift are produced conventionally.
It is still another object of this invention to provide a shoe of the type described which further includes enhancements which are included in the structure which defines the theoretically ideal stability plane.
It is still another object of this invention to provide a shoe of the type described wherein the enhancements which are included in the structure which defines the theoret:icall.y ideal _ g _ stability plane are applied to the single plane or t:he dual-plane embodiments of the invention as here described.
These and other objectives of the invention will become apparent from a detailed description of the invention which follows taken in conjunction with t:he accompanying drawings.
Brief Description of the Drawings In the drawings:
Fig. 1 is a perspective view of a typical running shoe known to the prior art to which the invention is applicable;
Fig. 2 shows, in Figs. 2A and 2B, the obstructed natural motion of the shoe heel in frontal planar cross secl~ion rotating inwardly or outwardly with the shoe sole having a flared bottom in a conventional prior art design such as in Fig. 1; and in Figs. 2C
and 2D, the efficient motion of a narrow rectangular shoe sole design;
Fig. 3 is a frontal plane cross section showing a shoe sole of uniform thickness that conforms to the natural shape of the human foot, the novel shoe design according to the invention;
Fig. 4 shows, :in Figs. 4A-4D, a load-bearing flat component of a shoe sole and naturally contoured stability side component, as well as a preferred horizontal periphery of the flat load-bearing portion of the shoe sole when using the sole of the invention;
Fig. 5 is diagrammatic sketch in Figs. 5A and 5B, showing the novel contoured side sole design according to the invention with variable heel lift;
Fig. 6 is a side view of the novel stable contoured shoe according to the invention showing the contoured side design;
_ g _ Fig. 7D is a top view of the shoe sole shown in Fig. 6, wherein Fig. 7A is a cross-sectional view of the forefoot portion taken along lines 7A of Figs. 6 or 7; Fig. 7B is a view taken along lines 7B of Figs. 6 and 7; and Fig. 7C is a crass-sectional. view taken along the heel along lines 7C in Figs. 6 and 7;
Fig. 8 is a drawn comparison between a conventional flared sole shoe of the prior art and the contoured shoe sole design according to the invention;
Fig. 9 shows, in Figs. 9A-9C, the extremely stable conditions for the novel shoe sole according to the invention in its neutral and extreme situations;
Fig. 10 is a side cross-sectional view of the naturally contoured sole side showing in Fig. l0A how the, sole maintains a constant distance from the ground during rotation of the shoe edge;
and showing in Fig. lOB how a conventional shoe sole side cannot maintain a constant distance from the ground.
Fig. 11 shows, in~Figs. 11A-11E, a plurality of side sagittal plane cross-sectional views showing examples of conventional sole thickness variations to which the invention can be applied;
Fig. 12 shows, in Figs. 12A-12D, frontal plane cross' sectional views of the shoe sole according to the invention showing a theoretically ideal stability plane and truncation=s of the sole side contour to reduce shoe bulk:
Fig. 13 shows, in Figs. 13A-13C, the contoured sole design according to the invention when applied to various tread and cleat patterns;
- to -Fig. 14 illustrates, in a rear view, an application of the sole according to the invention to a shoe to provide an aesthetically pleasing and functionally effective design;
Fig. 15 shows a fully contoured shoe sole design that follows the natural contour of the bottom of the foot as well as the sides.
Fig. 16 is a diagrammatic frontal plane cross-sectional view of static forces acting on the ankle joint and its position relative to the shoe sole according to the invention <9uring normal and extreme inversion and eversion motion.
Fig. 17 is a diagrammatic frontal plane' view of a plurality of moment curves of the center of gravity for various degrees of inversion for the shoe sole according to the invention, and contrasted to the motions shown in Fig. 2;
Fig. 18 shows, in Figs. 18A and 18B, a rear diagrammatic view of a human heel, as relating to a conventional shoe sole (Fig.
18A) and to the sole of the invention (Fig. 18B);
Fig. 19 shows the naturally contoured ides design extended to the other natural contours underneath the load-bearing foot such as the main longitudinal arch;
Fig. 20 illustrates the fully contoured shoe sole design extended to the bottom of the entire non-load-bearing foot;
Fig. 21 shows the fully contoured shoe sole design abbreviated along the sides to only essential structural support and propulsion elements;
Fig. 22 illustrates the application of the invention to provide a street shoe with a correctly contoured sole according to the invention and side edges perpendicular to the ground, as is typical of a street shoe;

Fig. 23 shows a method of establishing the theoretically ideal stability plane using a perpendicular to a tangent method;
Fig. 24 shows a circle radius method of establishing the theoretically ideal stability plane.
Fig. 25 illustrates an alternate embodiment of the invention wherein the sole structure deforms in use to follow a theoretically ideal stability plane according to the invention during deformation:
Fig. 26 shows an embodiment wherein the contour of the sole according to the invention is approximated by a plurality of line segments;
Fig. 27 illustrates an embodiment wherein the stability sides are determined geometrically as a section of a ring; and Fig. 28 shows a shoe sole design that allows for unobstructed natural eversion/inversion motion by providing torsional flexibility in the instep area of the shoe sole.
Fig. 29 is a diagrammatic chart showing, i.n Figs. 29A-29C, the outer contoured sides related to the sole of the novel shoe design according to the invention;
Fig. 30 is diagrammatic sketch in Figs. 30A and 30B, showing the novel contoured side sole design according to the invention with variable heel lift;
Fig. 31 is a side cross-sectional view of the quadrant sole side showing how the sole maintains a constant distance from the ground during rotation of the shoe edge;
Fig. 32 shows, in Figs. 32A-32C, frontal plane cross sectional views of the shoe sole according to the invention showing theoretically ideal stability plane and truncations of the sole edge quadrant to reduce shoe bulk;

Fig. 33 illustrates, in Figs. 33A-33C, heel cross sectional views of a conventional street shoe (Fig. 33A), and the application of the invention shown in Fig. 33B to provide a street shoe (Fig. 33C) with a correctly contoured sole according t:o the invention;
Fig. 34 shows, in a diagrammatic rear view, a relationship between the calcaneal tuberosity of the foot and the use of a wedge with the shoe of the invention;
Fig. 35 illustrates an alternate embodiment of the invention wherein the sole structure deforms in use to follow a theoretically ideal stability plane according to t:he invention during deformation;
Fig. 36 shows an embodiment wherein the contour of the sole according to the invention is approximated by a plurality of chord segments; and Fig. 37 shows in a diagrammatic view the theoretically ideal stability plane.
Fig. 38 shows several embodiments wherein the bottom sole includes most or all of the special contours of the new designs and retains a flat upper surface.
Fig. 39, in Figs. 39A - 39C, show frontal plane cross sections of an enhancement to the previously-described embodiment.
Fig. 40 shows, in Figs, 40A - 40C, the enhancement of Fig. 39 applied to the naturally contoured sides embodiment of the invention.
Detailed Description of the Preferred Embodiment A perspective view of an athletic shoe, such. as a typical running shoe, according to the prior art, is shown in Fig. 1 wherein a running shoe 20 includes an upper portion :?1 arid a sole 22. Typically, such a sole includes a truncated outwardly flared construction of the type best seen in Fig. 2 wherein the lower portion 22a of the sole heel is significantly wider than the upper portion 22b where the soles 22 joins the upper 21. A number of alternative sole designs are known to the art, including the design shown in U.S. Patent No. 4,449,306 to Cavanagh wherein an outer portion of the sole of the running shoe includes a rounded portion having a radius of curvature of about 20mm. The rounded portion lies along approximately the rear-half of the :Length of t:he outer side of the mid-sole and heel edge areas wherein the remaining border area is provided with a conventional flaring with the exception of a transition zone. The U.S. Patent to Misevich, No.
4,557,059 also shows an athletic shoe having a contoured sole bottom in the region of the first foot strike, in a shoe which otherwise uses an inverted flared sole.
In such prior art designs, and especially in athletic and in running shoes, the typical design attempts to achieve stability by flaring the heel as shown in Figs. 2A and 2B to a width of, for example, 3 to 3-1/2 inches on the bottom outer sole 22a of the average male shoe size (10D). On the other hand, the width of the corresponding human heel foot print, housed in the upper 21, is only about 2.25 in. for the average foot. Therefore, a mismatch occurs in that the heel is locked by the design into a firm shoe heel counter which supports the human heel by balding it tightly and which may also be re-enforced by motion control devices to stabilize the heel. Thus, for natural motion as is shown in Figs.
2A and 2B, the human heel would normally move in a normal range of 'motion of approximately 15~, but as shown in Figs. 2A and 2B the :human heel cannot pivot except within the shoe and is resisted by the shoe. Thus, Fig. 2A illustrates the impossibility of pivoting about the center edge of the human heel as would be conventional for barefoot support about a point 23 defined by a line 23a perpendicular to the heel and intersecting the bottom edge of upper 21 at a point 24. The lever arm force moment of th<a flared sole is at a maximum at 0° and only slightly less at a normal 7°
inversion or eversion and thus strongly resists such a natural motion as i.s illustrated in Figs. 2A and 2B. In Fig. 2A, the outer edge of the heel must compress to accommodate such motion. Fig.
2B illustrates that normal natural motion of the shoe is inefficient in that the center of gravity of the shoe, and the shod foot, is forced upwardly, as discussed later in connection with Fig. 17.
A narrow rectangular shoe sole design of heel width approximating human heel width is also known and is shown in Figs.
2c and 2D. It appears to be more efficient than the conventional flared sole shown in Figs. 2A and 2B. Since the shoe sole width is the same as human sole width, the shoe can pivot naturally with the normal 7° inversion/eversion motion of the running barefoot.
In such a design, the lever arm length and the vertical motion of the center of gravity are approximately half that of the flared sole at a normal 7° inversion/eversion running motion. However, the narrow, human heel width rectangular shoe design is extremely unstable and therefore prone to ankle sprain, so that it. has not been well received. Thus, neither of these wide or narrow designs is satisfactory.
Fig. 3 shows in a frontal plane cross section at the heel (center of ankle joint) the general concept of the applicant's design: a shoe sole 28 that conforms to the natural shape of the human foot 27 and that has a constant thickness (s) in frontal plane cross sections. The surface 29 of the bottom and sides of the foot 27 should corre;apond exactly to the upper surface 30 of the shoe sale 28. The shoe sole thickness as measured in frontal plane cross sections is defined as the shortest distance (s) between any point on the upper surface 30 of the shoe sole 28 and the lower surface 31 by definition, the surfaces 30 and 31 are consequently parallel (Figs. 23 and 24 wi7.l discuss measurement methods more fully). In effect, the applicant's general concept is a shoe sole 28 that wraps around and confcorms to t=he nature contours of the foot 27 as if the shoe sole 28 were made of a theoretical single flat sheet of shoe sole material of 'uniform thickness, wrapped around the foot with no distortion or deformation of that sheet as it is bent to the foot': contours. To overcome real world deformation problems associated with such bending or wrapping around contours, actual construction of the shoe sole contours of uniform thickness will preferably involve the use of multiple sheet lamination or injection molding techniques.
Figs. 4A, 4B, and 9C illustrate in frontal plane cross section a significant element of the applicant's shoe' design in its use of naturally contoured stabilizing sides 28a at the outer edge of a shoe sole 28b illustrated generally at the reference numeral 28. It is thus a main feature of the applicant's invention to eliminate the unnatural sharp bottom edge, especially of flared shoes, in favor of a naturally contoured shoe sole outside 31 as shown in Fig. 3. The side or inner edge 30a of the shoe sole stability side 28a is contoured like the natural foam on the side or edge of the human foot, as is the outside or outer edge 31a of the shoe sole stability side 28a to follow a theoretically ideal stability plane. According to the invention, the thickness (s) of the shoe sole 28 is maintained exactly constant, even if the shoe sole is tilted to either side, or forward or backward. Thus, the naturally contoured stabilizing sides 28a, according to the applicant's invention, are defined as the same as the thickness 33 of the shoe sole 28 so that, in cross section, the shoe sole comprises a stable shoe sole 28 having at its outer edge naturally contoured stabilizing sides 28a with a surface 31a representing a portion of a theoretically ideal stability plane and described by naturally contoured sides equal to the thickness (s) of the sole 28. The top of the shoe sole 30b coincides with the shoe wearer's load-bearing footprint, since in the case shown the shape of the foot is assumed to be load-bearing and therefore flat along the bottom. A top edge 32 of the naturally contoured stability side 28a can be located at any point along the contoured side 29 of the foot, while the inner edge 33 of the naturally contoured side 28a coincides with the perpendicular sides 34 of the load-bearing shoe sole 28b. In practice, the shoe sole 28 is preferably integrally formed from the portions 28b and 28a. Thus, the theoretically ideal stability plane includes the contours 31a merging into the lower surface 31b of the sole 28.
Preferably, the peripheral extent 36 of the load-bearing portion of the sole 28b of the shoe includes all of the support structures of the foot but extends no further than the outer edge of the foot sole 37 as defined by a load-bearing footprint, as shown in Fig. 4D, which is a top view of the upper shoe sole surface Sob. Fig. 4D thus illustrates a foot outline at numeral 37 and a recommended sole outline 36 relative thereto. Thus, a horizontal plane outline of the top of the load-bearing portion of the shoe sole, therefore exclusive of contoured stability sides, - 17 _ should, preferably, coincide as nearly as practicable with the load-bearing portion of the foot sole with which ~,t comes into contact. Such a horizontal outline, as best seen in Figs. 4D and 7D, should remain uniform throughout the entire thickness of the shoe sole eliminating negative or positive sole flare so that the sides are exactly perpendicular to the horizontal plane as shown in Fig. 4B. Preferably, the density of the shoe sole material is uniform.
Another significant feature of the applicant's invention is illustrated diagrammatically in Fig. 5. Preferably, as the heel lift or wedge 38 of thickness (sl) increases the total thickness (s + sl) of the combined midsole and outersole 39 of thickness (s) in an aft direction of the shoe, the naturally contoured sides 28a increase in thickness exactly the same amount accerding to the principles discussed in connection with Fig. 4. Thus, according to the applicant s design, the thickness of the inner edge 33 of the naturally contoured side is always equal to the constant thickness (s) of the load-bearing shoe sole 28b in. the frontal cross-sectional plane.
As shown in Fig.. 5B, for a shoe that follows a more conventional horizontal plane outline, the sole can be improved significantly according to the applicant's invention by the addition of a naturally contoured side 28a which correspondingly varies with the thickness of the shoe sole and changes in the frontal plane according to the shoe heel lift 38. Thus, as illustrated in Fig. 5B, the thickness of the naturally contoured side 28a in the heel section is equal to the thickness (s + sl) of the shoe sole 28 which is thicker than the shoe sole 39 thickness (s) shown in Fig. 5A by an amount equivalent to the heel lift 38 thickness (sl). In the generalized case, the thickness (s) of the contoured side is thus always equal to the thickness (s) at the forefoot of the shoe sole.
Fig. 6 illustrates a side cross-sectional view of a shoe to which the invention has been applied and is also shown in a top plane view in Fig. 7. Thus, Figs. 7A, 7B and 7C represent frontal plane cross-sections taken along the forefoot, at the base of the fifth metatarsal, and at the heel, thus illustrating that the shoe sole thickness is constant at each frontal plane cross-section, even though that thickness varies from.front to back, due to the heel lift 38 as shown in Fig. 6, and that the thickness of the naturally contoured sides is equal to the shoe sole thickness in each Fig. 7A-7C cross section. Moreover, in F'ig. 7D, a horizontal plane overview of the left foot, it can be seen that the contour of the sole follows the preferred principle in matching, as nearly as practical, the load-bearing sole print shown in Fig. 4D.
Fig. 8 thus contrasts in frontal plane cross section the conventional flared sole 22 shown in phantom outline and illustrated in Fig. 2 with the contoured shoe sole 28 according to the invention as shown in Figs. 3-7.
Fig. 9 is suitable for analyzing the shoe sole design according to the applicant's invention by contrasting the neutral situation shown in Fig. 9A with the extreme tilting situations shown in Figs. 9B and 9C. Unlike the sharp role edge of a conventional shoe as shown in Fig. 2, the effect of the applicant's invention having a naturally contoured side 28a is totally neutral allowing the shod foot to react naturally with the ground 43, in either an inver-sion or eversion mode. This occurs in part because of the unvarying thickness along the shoe sole edge which keeps the foot sole equidistant from the ground in a preferred case. Moreover, because the shape of the edge 31a of the shoe contoured side 28a is exactly like that of the edge of the foot, the shoe is enabled t<> react naturally with the ground in a manner as closely as. possible simulating the foot. Thus, in the neutral position shown .in Fig.
9, any point 40 on the surface of the shoe sole 30b c:lo~>est to ground lies at a distance (s) from the ground surface 43. That distance (s) remains constant even for extreme situations as seen in Figs. 9B and 9C.
A main point of the applicant's invention, as is illustrated in Figs. 9B and 9C, is that the design shown is stable in an in extremis situation. The theoretically ideal. plane of stability is where the stability plane is defined as sole thickness which is constant under all load-bearing points of the foot sole for any amount from 0° to 90° rotation of the sole to either side or front and back. In other words, as shown in Fig. 9, if the shoe is tilted from 0° to 90° to either side or from 0° to 90° forward or backw;:~rd representing a 0° to 90' foot dorsiflexion or 0°
to 90°
plantarflexion, the foot will remain stable because the sole thickness (s) between the foot and the ground always remain constant because of the exactly contoured sides. By remaining a constant distance from the ground, the stable shoe allows the foot to react to the ground as if the foot were bare while allowing the foot to be protected and cushioned by the shoe.
In its preferred embodiment, the new naturally contoured sides will effectively position and hold the foot onto the load-bearing foot print section of the shoe sole, reducing or eliminating the need for heel counters and other relatively rigid motion control devices.

Fig. l0A illustrates how the inner edge 30a of the naturally contoured sole side 28a is maintained at a constant distance (s) from the ground through various degrees of rotation of the edge 31a of the shoe sole such as is shown in Fig. 9.
Figure lOB shows how a c:onv~ntional shoe sole pivots around its lower edge 42, which is its center of rotation, instead of around the upper edge 40, which, as a result, is not maintained at constant distance (s) from the ground, as with the invention, but is lowered to .7(s) at 45° rotation and to zero at 90° rotation.
Fig. 11 shows typical conventional sagii=tal plane shoe sole thickness variations, such as heel lifts or wedges 38, or toe taper 38a, or full sole taper 38b, in Figs. 11A-11E and how the naturally contoured sidess 28a equal and therefore vary with those varying thicknesses as discussed in connection with Fig. 5.
Fig. 12 illustrates an embodiment of the invention which utilizes varying portions of the theoretically ideal stability plane 51 in the naturally contoured sides 28a in order to reduce the weight and bulk of the sole, while accepting a sacrifice in some stability of the shoe. Thus, Fig. 12A illustrates the preferred embodiment as described above in connection with Fig. 5 wherein the outer edge 31~a of the naturally contoured sides 28a follows a theoretically ideal stability plane 51. As in Figs, 3 and 4, the contoured surfaces 31a, and the lower surface of the sole 31b lie along the theoretically ideal stability plane 51. The theoretically ideal stability plane 51 is defined as the plane of the surface of the bottom of the shoe sole 31, wherein t;he shoe sole conforms to the natural shape of the wearer's foot sole, particularly the sides, and has a constant thi.ckn.ess in frontal plane cross sections. As shown in Fig. :128, an engineering trade-off results in an abbreviation within the theoretically ideal stability plane 51 by forming a naturally contoured side surface 53a approximating the natural contour of the foot (or more geometrically regular, which is less preferred) at an angle relative to t:he upper plane of the shoe sole 28 so that only a smaller portion of the contoured side 28a defined by the constant thickness lying along the surface 31a is coplanar with the theoretically ideal stability plane 51.
Figs. 12C and 12D show similar embodiments wherein each engineering trade-off shown results in progressively smaller portions of contoured side 28a, which lies along the theoretically ideal stability plane 51. The portion of the surface 31a merges into the upper side surface 53a of the naturally contoured side.
The embodiment of Fig. 12 may be desirable for portions of the shoe sole which are less frequently used so that the additional part of the side is used less frequently. For example, a shoe may typically roll out laterally, in an inversion mode, to about 20°
on the order of 100 times for each single time it rolls out to 40°.
For a basketball shoe, shown in Fig. 12B, the extra stability is needed. Yet, the added shoe weight to cover that infrequently experienced range of motion is about equivalent to covering the frequently encounter range. Since, in a racing shoe this weight might not be desirable, an engineering trade-off of the type shown in Fig. 12D is possible. A typical running/jogging shoe is shown in Fig. 12C. The range of possible variations is limitless but includes at least the maximum o.f 90° in inversion or evE~rsion, as shown in Fig. 12A.
Fig. 13 shows the theoretically ideal. stability plane 51 in defining embodiments of the shoe sole having differing tread or cleat patterns. Thus, Fig. 13 illustrates that the invention is applicable to shoe soles having conventional bottom treads.
Accordingly, Fig. 13A is similar to Fig. 12B further including a tread portion 60, while Fig. 13B is also similar to Fig. 12B
wherein the sole includes a cleated portion 61. The surface 63 to which the cleat bases are affixed should preferably be on the same plane and parallel the theoretically ideal stability plane 51, since in soft ground that surface rather than the cleats become load-bearing. The embodiment in Fig. 13C is similar to Fig. 12C
showing still an alternative tread construction 62. In each case, the load-bearing outer surface of the tread or cleat pattern 60-62 lies along the theoretically ideal stability plane 51.
Fig. 14 shows, in a rear cross sectional view, the application of the invention to a shoe to produce an aesthetically pleasing and functionally effective design. Thus, a practical design of a shoe incorporating the invention is feasible, even when applied to shoes incorporating heel lifts 38 and a combined midsole and outersole 39. Thus, use of a sole surface a:nd sole outer contour which track the theoretically ideal stability plane does not detract from the commercial appeal of shoes incorporating the invention.
Fig. 15 shows a fully contoured shoe sole design that follows the natural contour of all of the foot, the bottom as well as the sides. The fully contoured shoe sole assumes that the resulting slightly rounded bottom when unloaded, will deform under load and flatten just as the human foot bottom is slightly rounded unloaded but flattens under load; therefore, shoe sole material must be of such composition as to allow the natural deformation following that of the foot, The design applies particularly to the heel, but to the rest of the shoe sole as well. By providing the closest match to the natural shape of the foot, the fully contoured design allows the foot to function as naturally as possible. Under load, Fig. 15 would defoz-m by flattening to look essentially like Fig. 14. Seen in this light, the naturally contoured side design in Fig. 14 is a more conventional, conservative design that is a special case of the more general fully contoured design in Fig. 15, which is the closest to the natural form of the foot, but the least conventional. The amount of deformation flattening used in the Fig. 14 design, which obviously varies under different loads, is not an essential element of the applicant's :invent:ion.
Figs. 14 and 15 both show in frontal plane cross section the essential concept underlying this invention, the theoretically ideal stability plane, which is also theoretically ideal for efficient natural motion of all kinds, including running, jogging or walking. Fig. 15 shows the most general case of the invention, the fully contoured design, which conforms to the natural shape of the unloaded foot. For any given individual, the theoretically ideal stability plane 51 .is determined, first, by the desired shoe sole thickness (s) in a frontal plane cross section, and, second, by the natural shape of the :individual's foot surface 29, to which the theoretically ideal stability plane 51 is by definition parallel.
For the special case shown in Fig. 14, the: theoretically ideal stability plane f~~r any particular individual (or size average of individuals) .is determined, first, by the given frontal plane cross section shoe sole thickness (s) ; second, by the natural shape of the individual's foot; and, third, by the frontal plane cross section width of the individual's load-bearing footprint 30b, which is defined as the upper surface of the shoe sole that is in physical contact with and supports the human foot sole, as shown in Fig. 4.
The theoretically ideal stability plane for the special case is composed conceptually of two parts. Shown i.n Figs. 14 and 4 the first part is a line segment 31b of equal length and parallel to 30b at a constant distance (s) equal to shoe sole thickness.
This corresponds to a conventional shoe sole direct:Ly underneath the human foot, and also corresponds to the shoe sole portion 2.8b under flattened portion of the bottom of the load-bearing foot sole. The second part i.s the naturally contoured stability side outer edge 31a located at each side of the first part, line segment 31b. Each point on the contoured side outer edge 31a is located at a distance which is exact:Ly shoe sole thic:knes;~ (s) from the closest point on the contoured side inner- edge 30a, consequently, the inner and outer contoured edges 31a and 30a are by definition parallel.
In summary, the theoretically ideal stability plane is the essence of this invention because it is used to determine a geometrically precise botaom contour of the shoe sole based on a top contour that conforms to the contour of the foot. This invention specifically claims the exactly determined geometric relationship just described. It can be stated unec;uivocally that any shoe sole contour, even of similar contour, that exceeds the theoretically ideal stability plane will restrict= natural foot motion, while any less than that plane will d~_grade natural stability, in direct proportion to the amount of the deviation.
Fig. 16 illustrates in a curve 70 the range of side to side inversion/eversion motion of the ankle center of gravity 71 from the shoe according to the invention shown in frontal plane cross section at the ankle. Thus, in a static case where the center of gravity 71 lies at approximately the mid-point of the sole, and assuming that the shoe inverts or everts from 0° to 20°
to 40°, as shown in progressions 16A, 16B and 16C, the locus of points of motion for the center of gravity thus defines the curve 70 wherein the center of gravity 71 maintains a steady level motion with no vertical component through 40° of inversion or eversion.
For the embodiment shown, the shoe sole stability equilibrium point is at 28° (at point 74) and in no case is there a pivoting edge to define a rotation point as iri the case of Fig. 2. T:he inherently superior. side to side stability of the design provides pronation control (or eversion), as well as lateral (or inversion) control.
In marked contrast to conventional shoe sole designs, the applicant's shoe design creates virtually no abnormal torque to resist natural inversion/e:version motion or to des>tabilize the ankle joint.
Fig. 17 thus compares the range of motion of the center of gravity for the invention, as shown in curve 70, in comparison to curve 80 for the conventional wide heel flare and a~ curve 82 for a narrow rectangle the width of a human heel. Since the shoe stability limit is 28° in the inverted mode, the shoe sole is stable at the 20° approximate barefoot inversion limit. That factor, and the broad base of support rather than the sharp bottom edge of the prior art, make the contour design stable even in the most extreme case as shown :in Figs. 16A-16C and permit the inherent stability of the barefoot to dominate without interference, unlike existing designs, by providing constant, unvarying shoe sole thickness in frontal plane cross sections. The stak>ility superiority of the contour side design is thus clear when observing how much flatter its center of gravity curve 70 is than in existing popular wide flare design 80. The curve demonstrates that the contour side design has significantly more efficient natural 7°
inversion/eversion motion than the narrow rectangle design the width of a human heel, an~~ very much more efficient than the conventional wide flare design; at the same time, the contour side design is more stable in extremis than either conventional design because of the absence of destabilizing torque.
Fig. 18A illustrates, in a pictorial fashion, a comparison of a cross section at the ankle joint of a conventional shoe with a cross section of a shoe according to the invention when engaging a heel. As seen in Fig. 18A, when ttie heel of the foot 27 of the wearer engages an upper surface of the shoe sole 22, the shape of the foot heel and the shoe sole is :>uch that the conventional shoe sole 22 conforms to the contour of the ground 43 and not to the contour of the sides of the foot 27. As a result, the conventional shoe sole 22 cannot follow the natural 7°
inversion/eversion motion of the foot, and that normal motion is resisted by the shoe upper 21, especially when strongly reinforced by firm heel counters and motion control devices. This interference with natural motion represents the fundamental misconception of the currently available designs. That misconception on which existing shoe designs are based is that, while shoe uppers are considered as a part of the foot and conform to the shape of the foot, the shoe sole is functionally conceived of as a part of the ground and is therefore shaped flat like the ground, rather than contoured like the foot.
In contrast, the new design, as illustrated in Fig. 18B, illustrates a correct conception of the shoe sole 213 as a part of the foot and an extension of the foot, with shoe sole sides contoured exactly like those of the foot, and with the frontal plane thickness of the shoe sole between the foot Bind the ground always the same and therefore completely neutral to the natural motion of the foot. With the correct basic concejotion, as described in connection with this invention, the shoe can move _ 27 _ naturally with the foot, instead of restraining it, so both natural stability and natural efficient motion coexist, in the same shoe, with no inherent contradiction in design goals.
Thus, the contoured shoe design of the invention brings together in one shoe design the cushioning and protection typical of modern shoes, with the freedom from injury and functional efficiency, meaning speed, and/or endurance, typica7L of barefoot stability and natural freedom of motion. Significant speed and endurance improvements are anticipated, based on both improved efficiency and on the ability of a user to train harder without injury.
These figures also illustrate that the shoe heel cannot pivot plus or minus 7 degrees with the prior art shoe of Fig. 18A.
In contrast, the shoe heel in the embodiment of Fic~. 18B pivots with the natural motion of the foot heel.
Figs. 19A-D illustrate, in frontal plane cross sections, the naturally contoured sides design extended to the other natural contours underneath the load-bearing foot, such as the main longitudinal arch, the metatarsal (or forefoot) arch, and the ridge between the heads of the metatarsals (forefoot) and the heads of the distal phalanges (toes). As shown, the shoe sole thickness remains constant as the contour of the shoe sole follows that of the sides and bottom of the load-bearing foot. Fig.. 19E: shows a sagittal plane cross section of the shoe sole conforming to the contour of the bottom of the load-bearing foot, with thickness varying according to the heel lift 38. Fig. 19F shows a horizontal plane top view of the left foot that shows the areas 85 of the shoe sole that correspond to the flattened portions of t:he foot sole that are in contact with t_he ground when load-bearing. Contour lines 86 and 87 show approximately the relative height of the shoe sole contours above the flattened load-bearing areas 85 but within roughly the peripheral extent 35 of the upper surface of sole 30 shown in Fig. 4. A horizontal plane bottom view (mot shown) of Fig. 19F would be the exacts reciprocal or converse of Fig. 19F
(i.e. peaks and valleys contours would be exactly reversed).
Figs. 20A-D show,. in frontal plane cross :>ections, the fully contoured shoe sole design extended to the bottom of the entire non-load-bearing foot. Fig. 20E shows a sa~gittal plane cross section. The shoe sole contours underneath the foot are the same as Figs. 19A-E except that there are no flattened areas corresponding to the flattened areas of the load-bearing foot. The exclusively rounded contours of the shoe sole follow those of the unloaded foot. A heel lift 38, the same as that of Fig. 19, is incorporated in this embodiment, but is not shown in Fi.g. 20.
Fig. 21 shows the horizontal plane top view of the left foot corresponding to the fully contoured design described in Figs.
20A-E, but abbreviated along the sides to only essential strucaural support and propulsion elements. Shoe sole materia:L density can be increased in the unabbreviated essential elements to compensate for increased pressure loading there. The essential structural support elements are the base and lateral tuberosity of the calcaneus 95, the heads of the metatarsals 96, and th.e base of the fifth metatarsal 97. They must he supported both underneath and to the outside for stability. The essential propulsion element is the head of first distal phalange 98. The medial (inside) and lateral (outside) sides supporting the base of the calcaneus are shown in Fig. 21 oriented roughly along either side of the horizontal plane subtalar ankle joint axis, but can be' located also more conventionally along' the longitudinal axis of the shoe sole.
Fig. 21 shows that the naturally contoured stability sides need not be used except in the identified essential areas. Weight savings and flexibility improvements can be made by omitting the non-essential stability sides. Contour lines s5 through 86 show approximately the relative height of the shoe sole contours within roughly the peripheral extent 35 of the undeformed upper surface of shoe sole 30 shown in Fig. 4. A horizontal plane bottom view (not shown) of Fig. 21 would be the exact reciprocal or converse of Fig. 21 (i.e. peaks and valleys contours would be exactly reversed).
Fig. 22A shows a development of street shoes with naturally contoured sole sides incorporating the features of the invention. Fig. 22A develops a theoretically ideal ~~tability plane 51, as described above, for such a street shoe, wherein the thickness of the naturally contoured sides equals the shoe sole thickness. The resulting street shoe with a correctly contoured sole is thus shown in frontal plane heel cross section in Fig. 22A, with side edges perpendicular to the ground, as is typical. Fig.
22B shows a similar street shoe with a fully contoured design, including the bottom of the sole. Accordingly, the invention can be applied to an unconventional heel lift shoe, like a simple wedge, or to the most conventional design of a typical walking shoe with its heel separated from the forefoot by a hollow under the instep. The invention can be applied just at the shoe heel or to the entire shoe sole. With the invention, as so applied, the stability and natural motion of any existing shoe design, except high heels or spike heels, can be significantly improved by the naturally contoured shoe sole design.

Fig. 23 shows a method of measuring shoe sole thickness to be used to construct the theoretically ideal stability plane of the naturally contoured side design. The constant shoe sole thickness of this design is measured at any point on 'the contoured sides along a line that, first, is perpendicular to a line tangent to that point on the surface of the naturally contoured side of the foot sole and, second, that passes through the same foot sole surface point.
Fig. 24 illustrates another approach to constructing the theoretically ideal stability plane, and one that is easier to use, the circle radius method. By that method, the pivot point (circle center) of a compass is placed at the beginning of the foot sole's natural side contour (frontal plane cross section) and roughly a 90° arc (or much less, if estimated accurately) of a circle of radius equal to (s) or shoe sole thickness is drawn describing the area farthest away from the foot sole contour. That process is repeated all along the. foot sole's natural side contour at: very small intervals (the smaller, the more accurate). When all the circle sections are drawn, the outer edge farthest from the foot sole contour (again, frontal plane cross section) is estab:Lished at a distance of "s" and that outer edge coincides with the theoretically ideal stability plane. Both this method and that described in Fig. 23 would be used for both manual and CADCAM
design applications.
The shoe sole according to the invention can be made by approximating the contours, as indicated in Figs. 25A, 25B, and 26.
Fig. 25A shows a frontal plane cross section of a design wherein the sole material in areas 107 is so relatively soft that it deforms easily to the contour of shoe sole 28 of the proposed invention. In the proposed approximation as seen in Fig. 25E3, the heel cross section includes a sole upper surface 101 and a bottom sole edge surface 102 following when deformed an inset theoretically ideal stability plane 51. The sole edge surface 102 terminates in a laterally extending portion 103 joined to the heel of the sole 28. The laterally-extending portion 103 is made. from a flexible material and structured to cause its lower surface 102 to terminate during deformation to parallel the inset 1=heoretically ideal stability plane 51. Sole material in specific areas 107 is extremely soft to allow sufficient deformation. Thus, in a dynamic case, the outer edge contour assumes approximately t:he theoreti-cally ideal stability shape described above as a result of the deformation of the portion 103. The top surface 1.01 similarly deforms to approximately parallel the natural contour of the foot as described by lines 30a and 30b shown in Fig. 4.
It is presently contemplated that the controlled or programmed deformation can be provided by either of two techniques.
In one, the shoe sole sides, at especially the midsole, can be cut in a tapered fashion or grooved so that the bottom sole bends inwardly under pressure to the correct contour. The s~econc9 uses an easily deformable material 107 in a tapered manner on the sides to deform under pressure to the correct contour. While such techniques produce stability and natural motion resu:Lts which are a significant improvement over conventional designs, they are inherently inferior to contours produced by simple geometric shaping. First, the actual deformation must be produced by pressure which is unnatural and does not occur with a :bare foot and second, only approximations are possible by deformation, even with sophisticated design and manufacturing techniques, given an - 32 _ individual's particular running gait or body weight.. Thus, the deformation process is limited to a minor effort to correct the contours from surfaces approximating the ideal curve in the first instance.
The theoretically ideal stability plane can also be approximated by a plurality of line segments 110, such as tangents, chords, or other lines. as shown in Fig. 26. Both the upper surface of the shoe sole 28, which coincides with the side of the foot 30a, and the bottom surface 31a of the naturally contoured side can be approximated. While a single flat plane 110 approximation may correct. many of the biomechanical problems occurring with existing designs, because it ran provide a gross approximation of the both natural contour o.f the foot and the theoretically ideal stability plane 51, the single plane approximation is presently not preferred, since it is the least optimal. By increasing the number of flat planar surfaces formed, the curve more closely approximates the ideal exact design contours, as previously described. Single and double plane approximations are shown as line segments in the cross section illustrated in Fig. 26.
Fig. 27 shows a frontal plane cross section of an alternate embodiment for the invention showing stability sides component 28a that are determined in a mathematically precise manner to conform approximately to the sides of the foot. (The center or load-bearing shoe sole component 28b would be as described in Fig. 4). The component sides 28a would be a quadrant of a circle of radi~a (r + r'), where distance (r) must equal sole thickness (s); consequently the se.~b-quadrant of radius (r') is removed from quadrant (r + rl). In geometric terms, the component side 28a is thus a quarter or other section of a ring. The center of rotation 115 of the quadrants is selected to achieve a sole upper side surface 30a that closely approximates the natural contour of the side of the human foot.
Fig. 27 provides a direct bridge to another invention by the applicant, a shoe sole design with quadrant stability sides.
Fig. 28 shows ~~ shoe sole design that allows for unobstructed natural inversion/eversion motion of the calc:aneus by providing maximum shoe sole flexibility particularly between the base of the calcaneus 125 (heel) and the metatarsal heads 126 (forefoot) along an axis 120. An unnatural torsion occurs about that axis if flexibility is insufficient so that a conventional shoe sole interferes with the inversion/eversion motion by restraining it. The object of the design is to allow the relatively more mobile (in eversion and inversion) calcaneus to articulate freely and independently from the relatively more fixed forefoot, instead of the fixed or fused structure or lack of stable structure between the two in conventional designs. In a sense, freely articulating joints are created in the shoe sole that parallel those of the foot. The design is to remove nearly all of the shoe sole material between the heel and the forefoot, except under one of the previously described essential structura:L support elements, the base of the fifth metatarsal 97. An optional support for the main longitudinal arch 121 may also be retained for runners with substantial foot pronation, although would not be necessary for many runners. The forefoot can be subdivided (not shown) into its component essential structural support and propulsion elements, the individual heads of the metatarsal and the heads of the distal phalanges, so that each major articulating joint set. of the foot is paralleled by a freely articulating shoe sole support propulsion element, an anthropomorphic design; various aggregations of the subdivisions are also possible. An added benefit of the design is to provide better flexibility along axis 122 for the forefoot during the toe-off propulsive phase of the running stride, even in the absence of any other embodiments of the applicant.'s invention;
that is, the benefit exists for conventional shoe sole designs.
Fig. 28A shows in sagittal plane cross section a specific design maximizing flexibility, with large non-essential sections removed for flexibility and connected by only a top layer (horizontal plane) of non-stretching fabric 123 like * Dacron polyester or*Kevlar. Fig. 28B shows another specific design with a thin top sole layer 124 instead of fabric and a different structure for the flexibility sections: a design variation that provides greater structural support, but less flexibility, though still much more than conventional designs. Not shown is a sample, minimalist approach, which is comprised of single frontal plane slits in the shoe sole material (all layers or part) : the first midway between the base of the calcaneus and the bases of the fifth metatarsal, and the second midway between that base and the metatarsal heads. Fig. 28Cv shows a bottom view (horizontal plane) of the inversion/eversion flexibility design.
Fig. 29 illustrates in frontal plane cross section a significant element of the applicant's shoe design in its use of stabilizing quadrants 26 <3t the outer edge of a shoe sole 28b illustrated generally at the reference numeral 28. It is thus a main feature of the applicant's invention to eliminate the unnatural sharp bottom edge, especially of flared shoes, in favor of a rounded shoe sole edge 25 as shown in Fig. 29. The side or Trade mark edge 25 of the shoe sole 28 is contoured much like the natural form on the side or edge of the human foot, but in a geometrically precise manner to follow a theoretically ideal stability plane.
According to the invention, the thickness (s) of the shoe sole 28 is maintained exactly constant, even if the shoe sole is tilted to either side, or forward or backward. Thus, the sid<~ stabil.izing quadrants 26, according to the applicant's invention, are defined by a radius 25a which is the same as the thickness 3~4 of the shoe sole 28b so that, in cross section, the shoe sole comprises a stable shoe sole 28 having at its outer edges quadrants 26 a surface 25 representing a portion of a theoretically ideal stability plane and described by a radius 25a equal to the thickness (s) of the sole and a quadrant center of rotation at the outer edge 41 at the top of the shoe sole 30b, which coincides with the shoe wearer's load-bearing footprint. An outer edge :32 of the quadrant 26 coincides with the horizontal plane of the top of the shoe sole 28b, while the other edge of the quadrant 26 is perpendicular to the edge 32 and coincides with the perpendicular sides 34 of the shoe sole 28b. In practice, the shoe sale 28 is preferably integrally formed from the portions 28b and 26. The outer edge 32 may also extend to lie at.an angle relative to the sole upper surface. Thus, the theoretically ideal stability plane includes the contours 25 merging into the lower surface 31b of the sole 28b.
Preferably, the peripheral extent of the sole 36 of the shoe includes all of the support structures of the foot but extends no further than the outer edge of the foot sole 37 as defined by a load-bearing footprint, as shown in Fig. 4D, which is a top view of the upper shoe sole surface 30b. Fig. 4D thus illustrates a foot outline at numeral 37 and a recommended sole outline 36 relative thereto. Thus, a horizontal plane outline ~of the top of the shoe sole should, preferably, coincide as nearly as practicable with the load-bearing portion of the foot sole with which it comes into contact. Such a horizontal outline, as best seen in Fig. 4D, should remain uniform throughout the entire thickness of the shoe sole eliminating negative ar positive sole flare so that the sides are exactly perpendicular t.o the horizontal plane as shown in Fig.
29B. Preferably, the density of the shoe sole material is uniform.
Another significant feature of the applicant's :invention is illustrated diagrammatically in Fig. 30. Preferably, as the heel lift or wedge increases the thickness (s) of the shoe sole in an aft direction of the shoe, the side quadrants 26 increase about exactly the same amount according to the principles discussed in connection with Fig. 29. Thus, according to the applic:ant's design, the radius 25a of curvature (r) of the aide quadrant is always equal to the constant thickness (s) of the shoe sole in the frontal cross sectional plane.
As shown in Fig. 30B, for a shoe that follows a more conventional horizontal plane outline, the sole can be improved significantly according to the applicant's invention by the addition of outer edge quadrant 26 having a radius which correspondingly varies with the thickness of the shoe sole and changes in the frontal plane according to the shoe heel lift.
Thus, as illustrated in Fig. 30B, the radius of cu mature of the quadrant 26a is equal to the thickness s1 of the shoe sole 28b which is thicker than the shoe sole (s) shown in Fig. 30A by an amount equivalent to the heel lift (s-sl). Ln the generalized case, the radius (rl) of the quadrant is thus always equal to the thickness (s) of the shoe sole.
Fig. 31 illustrates how the center of rogation of the quadrant sole side 41 is maintained at a constant distance (s) from the ground through various degrees of rotation of the edge 25 of the shoe sole, in contrast to Figure lOB. By remaining a constant distance from the ground, the stable shoe allows the foot to react to the ground as if the foot were bare while allowing the foot to be protected and cushioned by the shoe. In its preferred embodiment, the new contoured design assumes that the shoe uppers 21, including heel counters and other motion control devices, will effectively position and hold the foot onto the load-bearing foot print section of the shoe :sole.
Fig. 32 illustrates an embodiment of the invention which utilizes only a portion of the theoretically ideal stability plane 51 in the quadrants 26 in order to reduce the weight and bulk of the sole, while accepting a sacrifice in some stability of the shoe. uhus, Fig. 32A illustrates the preferred embodiment as described above in connection with Fig. 30 wherein the outer quadrant 50 follows a theoretically ideal stability plane 51 about a center 52 and defines a surface 53 which is coplanar {or at an angle) with the upper surface of the shoe sole 54. As :in Fig. 29, the contoured surfaces 50, and the lower surface of the sole 54A
lie along the theoretically ideal stability plane. As shown in Fig. 32B, an engineering trade-off results in an abbreviation within the ideal stability plane 51 by forming a quadrant surface 53a at an angle relative to the upper plane of the shoe sole 54 so that only a portion of the quadrant defined by the radius lying along the surface 50a is coplanar with the theoretically ideal stability plane 51. Fig. 32C shows a similar embodiment wherein the engineering trade-off results in a portion 50b which lies along the theoretically ideal stability plane 51. The portion 50b merges into a second portion 56 which itself merges into the upper surface 53a of the quadrant.
The embodiment of Fig. 32 may be desirable for portions of the shoe sole which are less frequently used so that the additional part of the side is used less frequently. For ex<~mple, a shoe may typically roll out laterally, in an inversion mode, to about 20 degree on the order of 100 times for each single tame it rolls out to 40 degree. Ya_t, the added shoe weight to cover that entire range is about equivalent to covering the limited range.
Since in a racing shoe this weight might not be desirable, an engineering trade-off of the type shown in Fig. 32C is possible.
Fig. 33, in Figs. 33A-33C, shows a development of a street shoe with a contoured sole incorporating the features of the invention. Fig. 33A shows a heel cross section of a typical street shoe 94 having a sole portion 79 and a heel lift 8:L. Fig. 33B
develops a theoretically .ideal stability plane 51, as described above, for such a street shoe, wherein the radius (r) of curvature of the sole edge is equal to the shoe sole thickness. The resulting street shoe with a correctly contoured sole is thus shown in Fig. 33C, with a reduced side edge thickness for a less bulky and more aesthetically pleasing look. Accordingly, the invention can be applied to an unconventional heel lift shoe, like a simple wedge, or to the most conventional design of a typical walking shoe with its heel separated from the forefoot by a hollow under the instep. For the embodiment of Fig. 33, the theoretically ideal stability plane is determined by the shoe sole width and thickness, using an optimal human heel width as measured along the width of the hard human heel tissue on which the heel is assumed to rotate in an inversion/eversion mode. With the invention, as so applied, the stability and natural motion of any existing shoe design, except high heels or spike heels, can be significantly improved by contouring the bottom sole to the theoretically ideal stability plane.
Figs. 34A and 34B show the possible desirability of using wedge inserts 84 with the sole of the invention to support the calcaneal tuberosity. As seen in Fig. 34A, the c:alcaneal tuberosity 99 is unsupported when a shoe of the prior. art is inverted through an angle of 20 degrees. This is about the natural extreme limit of calcaneal inversion motion at which point the calcaneal tuberosity, located on the lateral side of the calcaneus, makes contact with the ground and restricts further lateral motion. When the conventional wide shoe sole reaches. such an inversion Limit, the sole leaves the calcaneal t:uberosity 99 completely unsupported in the area 100, whereas when the. foot is bare, the calcaneal tuberosity contacts the ground, providing a firm base of support. To address this situation, a saedge 84 of a relatively firm material, usually roughly equivalent to the density of the midsole and the heel lift, is located on top of the shoe sole under the insole in the lateral heel area to support the lateral calcaneal tuberosity. Thus, such a wedge support can also be used with the sole of the invention as shown in Fig. 34B.
Usually, such a wedge will taper toward the front of the shoe and is contoured to the shape of the calcaneus and its tu~berosity. If preferred, the wedge can be integrated with and be a part of a typical contoured heel of an insole.

The shoe sole according to the invention c:an be made by approximating the contours, as indicated in Figs. 35 and 36. In the proposed approximation as seen in Fig. 35, the heel cross section includes a sole upper surface 101 and a sole edge surface 104 following the theoretically ideal stability plane 51. The sole edge surface 104 terminates in a laterally extending portion 105 joined to the heel 106. The laterally-extending p~ort:ion 105 is made from a flexible material and structured to cause its lower surface 105a to terminate during deformation at the theoretically ideal stability plane. Thus, in a dynamic case, the outer edge contour assumes approximately the shape described above as a result of the deformation of the portion 105.
It is presently contemplated that the controlled or programmed deformation can be provided by either of two techniques.
In one, the shoe sole side<~, at especially the midsole, can be cut in a tapered fashion or grooved so that the bottom sole bends inwardly under pressure to the correct contour. The :second uses an easily daformable materiaa in a tapered manner on the sides to deform under pressure to the correct contour. While such techniques produce stability and natural motion results which are a significant improvement over conventional designs, they are inherently inferior to contours produced by simple geometric shaping. First, the actual deformation must be produced by pressure which is unnatural and does not occur with a bare foot and second, only approximations are possible by deformation, even with sophisticated design and manufacturing techniques, given an individual's particular running gait or body weight. Thus, the deformation process is limited to a minor effort to correct the contours from surfaces approximating the ideal curve in the first instance.
The theoretically ideal stability curve 51 can also be approximated by a plurality of line segments 110, such as tangents or chords, shown in Fig. 36. While a single flat plane approximation may correct many of the biomechanical problems occurring with existing designs, because it removes most the area outside of the theoretically ideal stability plane 51, the single plane approximation is presently not preferred, since it is the least optimal. By increasing the number of flat planar surfaces formed, the curve more closely approximates exactly the ideal design contour, as previous>ly described.
Fig. 37 shows in frontal plane cross section the essential concept underlying this invention, the theoretically ideal stability plane, which is also theoretical:Ly ideal for efficient natural motion of all kinds, including running, jogging or walking.
For any particular individual (or size: average of individuals), the theoretically ideal stability plane is determined, first, by the given shoe sole thickness (s), and, second, by the frontal plane cross section width of the individual's load-bearing footprint 30b, which is defined as the upper surface of the shoe sole that is in physical contact with and supports the human foot sole.
The theoretically ideal stability plane is composed conceptionally of two part:. The first part is a line segment 31b of equal length and parallel to 30b at a constant distance (s) equal to shoe sole thickness. This corresponds to a conventional shoe sole directly undernes~th the human foot. The second part is a quadrant edge 25 or quarter of a circle (which may be extended up to a half circle) at each side of the first part,, line segment 31b. The quadrant edge 25 is at radius (r), which is equal to shoe sole thickness (s) , from a center of rotation 41, which is the outermost point on each side of the line segment 30b. In summary, the theoretically ideal stability plane is the esaence of this invention because it is used to determine a geometrically precise bottom contour of the shoe sole. And, this invention specifically claims the exactly determined geometric relationship just described. It can be stated unequivocally that any shoe sole contour, even of similar quadrant contour, that exceeds the theoretically ideal stability plane will restrict natural foot motion, while any lesser contour will degrade natural stability.
That said, it is possible that an adjustment to a definition included in they preceding conception might be made at some point in the future not on a theoretical basis, but an empirical one. It is conceivable that, in contrast i~o the rest of the foot, a definition of line segment 30b at the base of the human heel could be the width of the very hard tissue (bone, cartilage, etc.), instead of the load--bearing footprint, .since i_t is possible that the heel width is the geometrically effective pivoting width which the shoe heel must precisely equal in order to pivot optimally with the human heel. For a typical male size lOD, that very hard tissue heel width is 1.75 inches, versus 2.25 inches for the load-bearing footprint of the heel. Though not optimal, narrower heel width 30b a:asumptions, even much narrower, may be used in non-athletic street shoes to obtain a significant propor-tion of the increases in stability and efficiency provided by the invention, while retaining a more traditional. appearance, espe-cially with higher heeled :shoes.
It is an empirical question, though, not a question of theoretical framework. Until more empirical work is done, optimal heel width must be based on assumption. The optimal width of the human heel pivot is, however, a scientific question to be determined empirically if it can be, not a change in the essential theoretically ideal stability plane concept claimed in the invention. Moreover, the more narrow the definition, the more important exact fit becomes and relatively minor individual misalignments could produce pronation control problems, for example, that negate any possible advantage.
Fig. 38 shows a non-optimal but interim or low cost approach to shoe sole construction, whereby the midsole and heel lift 127 are produced conventionally, or nearly ao (at least leaving the midsole bottom surface flat, though the sides can be contoured) , while the bottom or outer sole 128 includes most or all of the special contours of the new design. Not only would that completely or mostly limit the special contours to the bottom sole, which would be molded specially, it would also ease assembly, since two flat surfaces of the bottom of the midsole and the top of the bottom sole could be mated together with less difficulty than two contoured surfaces, as would be the case otherwise. 'The advantage of. this approach is seen in the naturally contoured design example illustrated in Fig. 38A, which shows some contours on the relatively softer midsole sides, which are subject to less wear but benefit from greater traction for stability and ease of deformation, while the re:Latively harder contoured bottom sole provides good wear for the load-bearing areas. Fig. 38B shows in a quadrant side design the concept applied to conventional street shoe heels, which are usually separated from the forefoot by a hollow instep area under the main longitudinal arch. Fig. 38C
shows in frontal plane cross section the concept applied to the quadrant sided or single plane design and indicating in Fig. 38D
in the shaded area 129 of the bottom sole that portion which should be honeycombed (axis on the horizontal plane) to reduce the density of the relatively hard outer sole to that of the mid:aole material to provide for relatively uniform shoe density. Fig. 38E shows in bottom view the outline of a bottom sole 128 made from flat material which can be conformed topologically to a contoured midsole of either the one or two plane designs by limiting the side areas to be mated to the essential support areas discussed in Fig.
21; by that method, the contoured midsole and flat bottom sole surfaces can be made to join satisfactorily by coinciding closely, which would be topological:Ly impossible if all of the side areas were retained on the bottom sole.
Figs. 39A-39C, frontal plane cross sections, show an enhancement to the previously described embodiments of the shoe sole side stability quadrant invention. As stated earlier, one major purpose of that design is to allow the shoe :>ole to pivot easily from side to side with the foot 90, thereby :following the foot's natural inversion and eversion motion; in conventional designs shown in Fig. 39a,. such foot motion is forced to occur within the shoe upper 21, which resists the motion. The enhancement is to position exactly and stabilize the foot, especially the heel, relative to the preferred embodiment of the shoe sole; doing so facilitates the shoe sole's responsiveness in following the foot's natural motion. Correct positioning is essential to the invention, especially when the very narrow or "hard tissue" definition of heel width is used. Incorrect or shifting relative position will reduce the inherent e:Eficiency and stability of the side quadrant design, by reducing the effective thickness of the quadrant side 26 to less than that of the shoe sole 28b. As shown in Fig. 39B and 39C, naturally contoured inner stability sides 131 hold the pivoting edge 31 of the load-bearing foot sole in the correct position for direct contact with the flat upper surface of the conventional shoe sole 22, so that the shoe sole thickness (s) is maintained at a constant thickness (s) in the stability quadrant sides 2E. when the shoe is averted or inverted, following the theoretically ideal stability plane 51.
The form'of the enhancement is inner shoe sole stability sides 131 that follow the natural contour of the sides 91 of the heel of the foot 90, thereby cupping the heel of the foot. The inner stability sides 131 can be located directly on the top surface of the shoe sole and heel contour, or direci~ly under the shoe insole (or integral to it), or somewhere in between. The inner stability sides are: similar in structure t:o heel cups integrated in insoles currently in common use, but differ because of its material density, which can be relatively firm like the typical mid-sole, not soft like the insole. The difference is that because of their higher relative density, preferably like that of the uppermost midsole, the inner stability sides function as part of the shoe sole, which provides structural support to the foot, not just gentle cushioning and abrasion protection of a shoe insole. In the broadest sense, though, insoles should be considered structurally and functionally as part of the shoe sole, as should any shoe material between foot and ground, like the bottom of the shoe upper in a slip-lasted shoe or the board in a board-lasted shoe.
The inner stability side enhancement is particularly useful in converting existing conventional shoe sole design embodiments 22, as constructed within prior art, to an effective embodiment of the side stability quadrant 26 invention. This feature is important in constructing prototypes and initial production of the invention, as well as an ongoing method of low cost production, since such production would be very close to existing art.
The inner stability sides enhancement is most essential in cupping the sides and back of the heel of the foot and therefore is essential on the upper edge of the heel of the shoe sole 27, but may also be extended around all or any portion of the remaining shoe sole upper edge. The size of the inner stability sides should, however, taper down in proportion to any reduction in shoe sole thickness in the sagittal plane.
Figs. 40A-40C, frontal plane cross sections, illustrate the same inner shoe sole stability sides enhancement as i.t applies to the previously describec9 embodiments of the naturally contoured sides design. The enhancement positions and stabilizes the foot relative to the shoe sole, and maintains the constant shoe sole thickness (s) of the naturally contoured sides 28a design, as shown in Figs. 40B and 40C; Fig. 40A shows a conventional design. The inner shoe sole stability sides 131 conform to the natural contour of the foot sides 29, which determine the theoretically ideal stability plane 51 for the shoe sole thickness (s;l. The other features of the enhancement as it applies to ithe naturally contoured shoe sole sides embodiment 28 are the same. as described previously under Figs. 39~,-39C for the side stabi:Lity qu<~drant embodiment. It is clear from comparing Figs. 40C anfa 39C that the two different approaches, that with quadrant sides .and that. with naturally contoured sides, can yield some similar resulting shoe sole embodiments through the use of inner stability sides 131. In essence, both approaches provide a low cost or interim method of adapting existing conventional "flat sheet" shoe manufacturing to the naturally contoured design described in previous figure:a.
Thus, it will clearly be understood by those skil:Led in the art that the foregoing description has been made in terms of the preferred embodiment and various changes and modifications may be made without departing from the scope of the present invention which is to be defined by the appended claims.

Claims (148)

1. A shoe sole for a shoe, including:
a medial side, a lateral side and a middle sole portion located between the lateral and medial sides;
a bottom sole;
a midsole which is softer than the bottom sole;
a heel lift;
an inner surface including at least one portion that is convexly rounded relative to a section of the sloe sole located directly adjacent to the convexly rounded portion of the inner surface, as viewed in a frontal plane cross-section, when the shoe sole is in an upright, unloaded condition;
an outer surface having an uppermost portion which extends to at least the height of the lowest point of the inner surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; characterized in that:
the outer surface includes at least one concavely rounded portion which extends down at least one side of the shoe sole to at least proximate a lowest point of the shoe sole side, the concavity of the concavely rounded portion of the outer surface is determined relative to an inner section of the shoe sole located directly adjacent to the concavely rounded portion of the outer surface, as viewed in a frontal plane cross-section, when the shoe sole is in an upright, unloaded condition; and wherein the concavely rounded portion of the outer surface of the side of the shoe solo includes a part formed by midsole, and the midsole part of the concavely rounded portion of the outer surface extends below a sidemost extent of the shoe sole side so that the rounded portion of the shoe sole side deforms to flatten easily under a wearer's body weight load during sideways motion of the shoe sole, thereby providing improved lateral stability.

2. A shoe sole for a shoe, including:

a) an inner surface for supporting the foot of an intended wearer;
b) an outer surface;
c) a medial side, a lateral side, and a middle sole portion located between the lateral and medial sides;
characterized in that the shoe sole further includes:
d) at least one concavely rounded portion located on one of the lateral and medial sides of the shoe sole, the concavity of the at least one concavely rounded portion being determined relative to an intended wearer's foot location inside the shoe, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
said at least one concavely rounded portion includes an outer surface having a portion that is concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded portion of the outer surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
said at least one concavely rounded portion includes an inner surface having a portion that is convexly rounded relative to a section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
and wherein the thickness of the shoe sole decreases gradually from a thickness at least at one of the concavely rounded portions of the shoe sole to a lesser thickness on at least one side of the concavely rounded portion, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

3. A shoe sole for a shoe, the shoe sole including:
a sole lateral side, a sole medial side and a middle sole portion located between the sole lateral side and the sole medial side;
a bottoms sole;
a midsole which is softer than the bottom sole;
an inner surface having at least a portion that is convexly rounded relative to a section of the shoe sole located directly adjacent the convexly rounded inner surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
the midsole having an uppermost part which extends to at least the height of the lowest point of the inner surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; characterized in that:
the outer surface of the middle sole portion includes at least one concavely rounded portion which extends through the lowest point of the shoe sole, the concavity of the concavely rounded portion is determined relative to an inner section of the shoe sole directly adjacent to the concavely rounded outer surface portion, as viewed in a frontal plane cross-section, when the shoe sole is in an upright, unloaded condition.

4. A shoe sole for a shoe, including:
a sole lateral side, a sole medial side, and a middle sole portion located between the sole lateral and medial sides;
a midsole having an inner surface of the midsole and an outer midsole surface, the midsole including portions located in at least the middle sole portion and a first side of the shoe sole;
the sole lateral side including a lateral sidemost section located outside of a vertical line drawn at the sidemost extent of the inner surface of the midsole;
the sole medial side including a medial sidemost section located outside of a vertical line drawn at the sidemost extent of the inner surface of the midsole;
an bottom sole;
the outer midsole surface of the portion of the midsole located in the first side of the shoe sole extending up the first side of the shoe sole to a vertical height above the vertical height of the lowest point of the inner surface of the midsole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; and the portion of the midsole located in the first side of the shoe sole having a greatest thickness, measured between the inner and outer midsole surfaces, that is greater than a thickness between the inner and outer midsole surfaces of the portion of the midsole located in the middle sole portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
characterized in that:
the outer midsole surface of the portion of the midsole located in the first side of the shoe sole includes a lowermost part that is concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded outer surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

5. A shoe sole as claimed in any one of claims 1 and 3-4, wherein the thickness of the shoe sole decreases gradually from a thickness at least at the location of one of the concavely rounded portions of the outer surface of the shoe sole to a lesser thickness on at least one side of the concavely rounded portion of the outer surface, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

6. A shoe sole as claimed in claim 5, wherein a portion of the outer surface of the area of the shoe sole wherein the sole thickness decreases gradually, as viewed in a horizontal plane, is concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded portion of the outer surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

7. A shoe sole as claimed in any one of claims 5-6, wherein the thickness of the shoe sole at least at one concavely rounded portion of the shoe sole decreases gradually to zero on at least one side of a concavely rounded portion on the lateral or medial side of the shoe sole, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

8. The shoe sole of claim 1, wherein the midsole part of the concavely rounded portion of the outer surface includes an upper part of the outer surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

9. A shoe sole as claimed in any one of claims 2-3, wherein an interior portion of the at least one concavely rounded portion of the shoe sole located between the concavely rounded outer surface portion and the convexly rounded inner surface portion includes at least part of the midsole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

10. A shoe sole as claimed in claim 4, wherein an uppermost part of a midsole side portion extends to the height of the lowest point of the inner surface of the same side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

11. A shoe sole as claimed in any one of claims 4 and 10, wherein an uppermost part of a midsole side portion extends above the height of the lowest point of the inner surface of the same side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

12. A shoe sole as claimed in any one of claims 4 and 10-11, wherein the inner surface of the portion of the midsole located in the first side of the shoe sole further includes a portion that is convexly rounded relative to an inner section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

13. A shoe sole as claimed in claim 12, wherein the convexly rounded portion of the inner surface of the midsole extends substantially to a sidemost extent of the inner surface of the midsole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

14. A shoe sole as claimed in any one of claims 12-13, wherein the convexly rounded portion of the inner surface of the midsole is substantially coextensive with at least one concavely rounded portion of the outer midsole surface of the same portion of the midsole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

15. A shoe sole as claimed in any one of claims 4 and 10-14, wherein the concavely rounded portion of the outer midsole surface extends to the sidemost extent of the outer midsole surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

16. A shoe sole as claimed in any one of claims 4 and 10-14, wherein the concavely rounded portion of the outer midsole surface extends continuously through the sidemost extent of the outer midsole surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

17. A shoe sole as claimed in any one of claims 4 and 10-14, wherein the concavely rounded portion of the outer midsole surface extends continuously through the lowermost part of the outer midsole surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

18. A shoe sole as claimed in any one of claims 4 and 10-16, wherein at least one portion of the midsole extends into a second side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
the lowermost part of the outer midsole surface of the portion of the midsole located in the second side of the shoe sole is concavely rounded relative to an intended wearer's foot location inside the shoe, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; and the portion of the midsole located in the second side of the shoe sole and which has a concavely rounded outer midsole surface also has a thickness that is greater than the thickness of a portion of the midsole located in the middle sole portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

19. A shoe sole as claimed in claim 18, wherein the concavely rounded portion of the outer midsole surface of the portion of the midsole located in the second side of the shoe sole extends to the sidemost extent of the outer midsole surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

20. A shoe sole as claimed in claim 18, wherein the concavely rounded portion of the outer midsole surface of the portion of the midsole located in the second side of the shoe sole extends continuously through the sidemost extent of the outer midsole surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

21. A shoe sole as claimed in any one of claims 18-20, wherein the first and second sides of the shoe sole are viewed in the same frontal plane cross-section.

22. A shoe sole as claimed in any one of claims 4 and 10-21, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded outer surface portion, at one or more locations which substantially correspond to the positions of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe:
the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in a frontal plane cross-section at the one or more locations when the shoe sole is in an upright, unloaded condition.

23. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus and the lateral tuberosity of the calcaneus, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

24. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the head of the fifth metatarsal and the head of the first metatarsal, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

25. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the head of the fifth metatarsal, the head of the first metatarsal, the base of the calcaneus, and the lateral tuberosity of the calcaneus, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

26. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of two of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

27. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of three of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

28. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of four of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe; the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

29. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of five of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

30. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of six of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition.

31. A shoe sole as claimed in claim 22, wherein the outer midsole surface of the at least one portion of the midsole located in a side of the shoe sole is concavely rounded, at least at locations which substantially correspond to the positions of the following structural support and propulsion elements of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the head of the first distal phalange, the head of the first metatarsal, the base of the fifth metatarsal, the head of the fifth metatarsal, and the main longitudinal arch, as viewed in frontal plane cross-sections at said locations when the shoe sole is in an upright, unloaded condition,

32. A shoe sole as claimed in any one of claims 4 and 10-31, wherein the at least one portion of the midsole located in a side of the shoe sole includes a midsole section of greatest thickness, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition, and at least one tapered portion at a location adjacent to, and anterior or posterior to the midsole section of greatest thickness, the tapered portion having a thickness that decreases from the section of greatest thickness to a lesser thickness, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

33. A shoe sole as claimed in claim 32, wherein the thickness of the at least one tapered portion of the midsole gradually decreases from the midsole section of greatest thickness to the lesser thickness, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

34. A shoe sole as claimed in any one of claims 32-33, wherein the at least one tapered portion of the midsole is concavely rounded relative to an intended wearer's foot location inside the shoe, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

35. A shoe sole as claimed in any one of claims 32-34, wherein the at least one tapered portion of the midsole is located anterior to the midsole section of greatest thickness, as viewed in a horizontal plane.

36. A shoe sole as claimed in any one of claims 32-34, wherein the at least one tapered portion of the midsole is located posterior to the midsole section of greatest thickness, as viewed in a horizontal plane.

37. A shoe sole as claimed in any one of claims 32-34, including at least two tapered portions of the midsole, one tapered portion of the midsole located posterior to the midsole section of greatest thickness and a second tapered portion of the midsole located anterior to the midsole section of greatest thickness, as viewed in a horizontal plane.

38. A shoe sole as claimed in any one of claims 4 and 10-37, wherein an inner surface of at least one side of the midsole includes at least one portion that conforms to the shape of the outer surface of an intended wearer's foot when inside the shoe, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

39. The shoe sole of any one of claims 1-3, wherein the frontal plane cross-section is located in the heel area.

40. A shoe sole as claimed in any one of claim 1, wherein an uppermost portion of the upper side surface of the shoe sole side extends to a point at least above the height of the lowest point of the inner surface of the same side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

41. A shoe sole as claimed in any of claims 1-2 and 4-40, wherein at least part of the middle sole portion of the outer surface of the shoe sole is substantially flat, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

42. A shoe sole as claimed in any one of claims 1-3, including midsole;
wherein the medial side of the shoe sole includes a sidemost medial section at a location outside of a straight, vertical line extending through the medial side of the shoe sole at the sidemost extent of the inner surface of the medial side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
wherein the lateral side of the shoe sole includes a sidemost lateral section at a location outside of a straight, vertical line extending through the lateral side of the shoe sole at the sidemost extent of the inner surface of the lateral side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; and wherein the midsole extends into the sidemost section of at least the side of the shoe sole which has at least one concavely rounded outer surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

43. The shoe sole of any one of claims 1-42, wherein:
at least a part of a bottom surface of the midsole and at least a part of a top surface of the bottom sole are substantially flat, as viewed in the frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

44. The shoe sole of any one of claims 1-43, wherein the shoe sole includes at least two concavely rounded portions of the outer surface each including midsole and which are located on opposing sides of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

45. The shoe sole of any one of claims 1-44, wherein:
the upper surface of a side portion of the bottom sole is substantially flat, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

46. The shoe sole of any one of claims 1-45, including a combined midsole and lift, and wherein the thickness of the midsole and lift of a portion of the shoe sole having a concavely rounded outer surface, as measured in a first frontal plane cross-section when the shoe sole is in an upright, unloaded condition, is greater than the thickness of the midsole and lift of a different sole portion which does not have a concavely rounded outer surface, as measured in a second frontal plane cross-section, when the shoe sole is in an upright, unloaded condition.

47. The shoe sole of claim 46, wherein the lift is a heel lift.

48. The shoe sole of any one of claims 1-47, wherein the at least one concavely rounded portion of the outer surface is also concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded portion of the outer surface, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

49. The shoe sole of any one of claims 1-48, wherein the portion of the shoe sole which has a concavely rounded outer surface further includes an area of increased material density to form a structural support or propulsion element for the foot of an intended wearer.

50. A shoe sole as claimed in any one of claims 1-49, wherein at least part of the concavely rounded portion of the outer surface of the shoe sole is formed by a plurality of substantially straight line segments which, taken together, approximate a concavely rounded surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

51. A shoe sole as claimed in any one of claims 1-50, wherein a heel area of the shoe sole has a thickness that is greater than the thickness of the shoe sole in a forefoot area.

52. A shoe sole as claimed in any one of claims 1-51, including a tread pattern on at least part of the outer surface of the shoe sole.

53. A shoe sole as claimed in any one of claims 1-52, wherein at least part of the inner surface of at least one portion of the shoe sole having a concavely rounded outer surface is also convexly rounded relative to a section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface, as viewed in a horizontal plane when the shoe sole is in an upright, unloaded condition.

54. A shoe sole as claimed in any one of claims 1-53, wherein the shoe sole further includes a concavely rounded outer surface portion that extends through a lowermost heel area of the shoe sole, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

55. A shoe sole as claimed in any one of claims 1-54, wherein the shoe sole has a substantially uniform thickness from a lowermost heel area to a rearmost heel extent, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

56. A shoe sole as claimed in any one of claims 1-55, wherein the shoe sole has a substantially uniform thickness from a lowermost heel area through a rearmost heel extent, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

57. A shoe sole as claimed in any one of claims 1-56, wherein at least part of the outer surface of at least one portion of the shoe sole having a concavely rounded outer surface is also concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded portion of the outer surface, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition; and at least part of the inner surface of the at least one concavely rounded portion of the shoe sole is also convexly rounded relative to a section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

58. A shoe sole as claimed in claim 57, wherein the thickness of the shoe sole decreases gradually in an upper rear heel portion, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

59. A shoe sole as claimed in any one of claims 1-58, wherein the thickness of the shoe sole at least at one portion of the shoe sole leaving a concavely rounded outer surface decreases gradually between a sidemost extent and an uppermost extent of the side of the shoe sole, and, in the uppermost extent of the side of the shoe sole, the thickness is the shortest distance between a point on the inner surface and the closest point on one of the outer surface or the upper side surface, all as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

60. A shoe sole as claimed in any one of claims 1-59, including a heel lift;
wherein the medial side of the shoe sole includes a sidemost medial section at a location outside of a straight, vertical line extending through the medial side of the shoe sole at the sidemost extent of the inner surface of the medial side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
wherein the lateral side of the shoe sole includes a sidemost lateral section at a location outside of a straight, vertical line extending through the lateral side of the shoe sole at the sidemost extent of the inner surface of the lateral side of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition; and wherein the heel lift extends into the sidemost section of at least the side of the shoe sole which has at least one concavely rounded outer surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

61. A shoe sole as claimed in any one of claims 1-60, wherein the shoe is an athletic shoe.

62. A shoe sole as claimed in any one of claim 60, wherein the bottom sole extends into a sidemost section of the shoe sole and at least a portion of the outer surface of the bottom sole in the sidemost section of the shoe sole is concavely rounded relative to an inner section of the shoe sole located directly adjacent to the concavely rounded outer surface portion, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

63. The shoe sole of any one of claims 1-62, wherein the outer surface forms an arc of more than 90° from the concavely rounded portion to an uppermost part, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

64. The shoe sole of any one of claims 1-63, wherein the portion of the shoe sole which has a concavely rounded outer surface further includes an area of increased material firmness to form a structural support or propulsion element for the foot of an intended wearer.

65. The shoe sole of any one of claims 1-64, wherein the convexly rounded portion of the inner surface extends substantially to a sidemost extent of the inner surface, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

66. The shoe sole of any one of claims 1-65, wherein:
the concavely rounded portion of the outer surface extends up at least one shoe sole side to a location on the shoe sole side proximate to a sidemost extent of the shoe sole side, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

67. The shoe sole of any one of claims 1-65, wherein:
the concavely rounded portion of the outer surface extends up at least one shoe sole side through a sidemost extent of the shoe sole side, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

68. The shoe sole of any one of claims 1-67, wherein:
at least a lowermost part of the concavely rounded portion of the outer surface is formed by bottom sole.

69. A shoe sole as claimed in any one of claims 1-68, wherein the at least one concavely rounded portion of the outer surface is located at one or more locations on the shoe sole proximate to the locations of one or more of the following parts of an intended wearer's foot when inside the shoe: the base of the calcaneus, the lateral tuberosity of the calcaneus, the base of the fifth metatarsal, the head of the fifth metatarsal, the head of the first metatarsal, and the head of the first distal phalange.

70. A shoe sole as claimed in claim 69, including a concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the first metatarsal of an intended wearer's foot when inside the shoe.

71. A shoe sole as claimed in claim 69, including a concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the first distal phalange of an intended wearer's foot when inside the shoe.

72. A shoe sole as claimed in claim 69, including a concavely rounded outer surface portion at a location substantially corresponding to the location of the base of the calcaneus of an intended wearer's foot when inside the shoe.

73. A shoe sole as claimed in claim 69, including a concavely rounded outer surface portion at a location substantially corresponding to the location of the lateral tuberosity of the calcaneus of an intended wearer's foot when inside the shoe.

74. A shoe sole as claimed in claim 69, including a concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the fifth metatarsal of an intended wearer's foot when inside the shoe.

75. A shoe sole as claimed in claim 71, wherein the at least one concavely rounded outer surface portion extends to the front of the shoe sole.

76. A shoe sole as claimed in claim 72, wherein the at least one concavely rounded outer surface portion extends to the rear of the shoe sole.

77. A shoe sole as claimed in any one of claims 1-69, including a concavely rounded portion on each of the lateral and medial sides of the shoe sole, at least one of said concavely rounded portions extending to the middle sole portion of the shoe sole at a location substantially corresponding to the location of at least one of the base of the calcaneus and the lateral tuberosity of the calcaneus of an intended wearer's foot when inside the shoe, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

78. A shoe sole as claimed in any one of claims l-69, including a first concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the fifth metatarsal of an intended wearer's foot when inside the shoe, an area of lesser thickness adjacent to a posterior side of the first concavely rounded outer surface portion, and a second concavely rounded outer surface portion at a location substantially corresponding to the location of the lateral tuberosity of the calcaneus of an intended wearer's foot when inside the shoe, and an area of lesser thickness adjacent to an anterior side of the second concavely rounded outer surface portion.

79. A shoe sole as claimed in any one of claims 1-69, including a first concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the first distal phalange of an intended wearer's foot when inside the shoe, a second concavely rounded outer surface portion at a location substantially corresponding to the location of the head of the first metatarsal of an intended wearer's foot when inside the shoe, and an area of lesser thickness located between said first and second concavely rounded outer surface portions.

80. A shoe sole as claimed in any one of claims 1-79, including at least three concavely rounded outer surface portions.

81. A shoe sole as claimed in any one of claims 1-79, including at least four concavely rounded outer surface portions.

82. A shoe sole as claimed in any one of claims 1-79, including at least five concavely rounded outer surface portions.

83. A shoe sole as claimed in any one of claims 1-79, including at least six concavely rounded outer surface portions.

84. A shoe sole as claimed in any one of claims 69-83, wherein at least one concavely rounded outer surface portion is centered substantially around the position of one of the structural support and propulsion elements of an intended wearer's foot when inside the shoe, as viewed in both a frontal plane cross-section and a horizontal plane, when the shoe sole is in an upright, unloaded condition.

85. A shoe sole as claimed in any one of claims 69-84, wherein at least one concavely rounded outer surface portion encompasses substantially all of an area of the shoe sole which corresponds to the area of one of the structural support and propulsion elements of an intended wearer's foot when inside the shoe, as viewed in both a frontal plane cross-section and a horizontal plane, when the shoe sole is in an upright, unloaded condition.

86. A shoe sole as claimed in claim 85, wherein the at least one concavely rounded outer surface portion coincides substantially with the area of the shoe sole which corresponds to the area of one of the structural support and propulsion elements of an intended wearer's foot when inside the shoe, as viewed in both a frontal plane cross-section and a horizontal plane, when the shoe sole is in an upright, unloaded condition.

87. A shoe sole as claimed in any one of claims 1-86, wherein the thickness of the shoe sole is defined as the shortest distance between any point on the inner surface of the shoe sole and the nearest point on the outer surface of the shoe sole, as viewed in a frontal or sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

88. A shoe sole as claimed in any one of claims 1-24, wherein the thickness is defined as a radial thickness; and the radial thickness is the length of a line extending perpendicular to a line tangent to the inner surface of the midsole from the inner surface of the midsole to the outer midsole surface at the measured location, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

89. A sole for a shoe having at least one side portion with rounded surfaces to increase at least one of lateral and medial stability of the sole, the shoe sole including:
a heel area at a location substantially corresponding to the location of a heel portion of an intended wearer's foot when inside the shoe;
a sole forefoot area at a location substantially corresponding to the location of a forefoot portion of an intended wearer's foot when inside the shoe;

a sole midtarsal area located between the heel area and the sole forefoot area;
the sole including a midsole component and an outsole component;
the sole including a sidemost lateral section and a sidemost medial section, each at a location outside of a straight vertical line extending through the sole at a sidemost extent of the inner surface of a midsole component, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition;
a sole outer surface of at least part of the sole midtarsal area is substantially convexly rounded, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the convexity being determined relative to an intended wearer's foot location inside the shoe;
at least one midtarsal area sole side located at one or more of a sole medial side and a sole lateral side of the sole midtarsal area, the sole medial and lateral sides being separated by a middle sole portion;
characterized in that:
each midtarsal area sole side including a concavely rounded portion of the outer surface of the sole, as viewed in a frontal plane cross-section in the sole midtarsal area when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an inner section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface;
each midtarsal area sole side including a convexly rounded portion of the inner surface of a midsole component, as viewed in a frontal plane cross-section in the sole midtarsal area when the shoe sole is in an upright, unloaded condition, the convexity being determined relative to an inner section of the shoe sole located directly adjacent to the convexly rounded portion of the inner surface; and wherein each said midtarsal area sole side also includes a midsole component extending into the sidemost section of the midtarsal area sole side, as viewed in a frontal plane cross-section in the sole midtarsal area when the shoe sole is in an upright, unloaded condition; and each said midtarsal area sole side further includes an upper part of a midsole component extending up the midtarsal area sole side to above the height of the lowest point of the inner surface of a midsole component of the same midtarsal area sole side, as viewed in a frontal plane cross-section in the sole midtarsal area when the shoe sole is in an upright, unloaded condition.

90. The shoe sole as claimed in claim 89, wherein one said midtarsal area sole side is located on the sole lateral side of the sole midtarsal area.

91. The shoe sole as claimed in claim 89, wherein one said midtarsal area sole side is located on the sole medial side of the sole midtarsal area.

92. The shoe sole as claimed in claim 89, including two midtarsal area sole sides, one being located on the sole medial side of the sole midtarsal area and the second being located on the sole lateral side of the sole midtarsal area.

93. The shoe sole as claimed in any one of claims 89-92, further including at least one heel area sole side located at one or more of a sole medial side and a sole lateral side of the heel area, each heel area sole side including a concavely rounded portion of both the inner surface of a midsole component and the outer surface of the sole, as viewed in a frontal plane cross section in the heel area when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an intended wearer's foot location inside the shoe.

94. The shoe sole as claimed in claim 93, wherein one said heel area sole side is located on the sole lateral side of the heel area.

95. The shoe sole as claimed in claim 93, wherein one said heel area sole side is located on the sole medial side of the heel area.

96. The shoe sole as claimed in claim 93, including two heel area sole sides, one being located on the sole medial side of the heel area and the second being located on the sole lateral side of the heel arear.

97. The shoe sole as claimed in anyone of claims 89-96, wherein the heel area includes the following combined components: a midsole component and an outsole component.

98. The shoe sole as claimed in anyone of claims 89-97, further including at least one forefoot area sole side located at one or more of a sole medial side and a sole lateral side of the sole forefoot area, each forefoot area sole side including a concavely rounded portion of both the inner surface of a midsole component and the outer surface of the sole, as viewed in a frontal plane cross-section in the sole forefoot area when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an intended wearer's foot location inside the shoe.

99. The shoe sole as claimed in claim 98, wherein one said forefoot area sole side is located on the sole lateral side of the sole forefoot area.

100. The shoe sole as claimed in claim 98, wherein one said forefoot area sole side is located on the sole medial side of the sole forefoot area.

101. The shoe sole as claimed in claim 98, including two forefoot area sole sides, one being located on the sole medial side of the sole forefoot area and the second being located on the sole lateral side of the sole forefoot area.

102. The shoe sole as claimed in any one of claims 89-101, wherein one or more of the heel area and the sole forefoot area include the following combined components: a midsole component and an outsole component.

103. The shoe sole as claimed in claim 102, wherein a midsole component extends into the sidemost section of each heel area sole side, each forefoot area sole side, or each heel area sole ride and each forefoot area sole side, as viewed in a frontal plane cross-section in one or more of the sole heel and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

104. The shoe sole as claimed in claim 103, wherein an upper part of a midsole component extends up each heel area sole side, each forefoot area sole side, or each heel area sole side and each forefoot area sole side, to above the height of the lowest point of the inner surface of a midsole component of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

105. The shoe sole as claimed in any one of claims 102-104, wherein an outsole component extends into the sidemost section of at least one of each heel area sole side, each midtarsal area sole side and each forefoot area sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

106. The shoe sole as claimed in claim 105. wherein an upper part of an outsole component extends up at least one of each heel area sole side, each midtarsal area sole side and each forefoot area sole side, to above the height of the lowest point of the inner surface of a midsole component of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

107. The shoe sole as claimed in any one of claims 89-106, wherein the concavely rounded portion of the outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends through a lowermost portion of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

108. The shoe sole as claimed in any one of claims 89-107, wherein the concavely rounded portion of the outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends into the middle sole portion, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

109. The shoe sole as claimed in any one of claims 89-108, wherein the concavely rounded portion of the outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends to a centerline of the sole middle part, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

110. The shoe sole as claimed in any one of claims 89-109, wherein the concavely rounded portion of the sole outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends continuously through a sidemost extent of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

111. The shoe sole as claimed in any one of claims 89-109, wherein the concavely rounded portion of the sole outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends up the same sole side to at least the height of the lowest point of the inner surface of a midsole component of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

112. The shoe sole as claimed in any one of claims. 89-109, wherein the -74-~~~~~~~ ~~~

concavely rounded portion of the sole outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends up the same sole side to above the height of the lowest point of the inner surface of a midsole component of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

113. The shoe sole as claimed in any one of claims 89-109, wherein the concavely rounded portion of the sole outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends up the forefoot area sole side continuously through the portion of the same sole side at the height of the lowest point of the inner surface of a midsole component of the same sole side, as viewed in a frontal plane cross-section in one or snore of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

114. The shoe sole as claimed in any one of claims 89-109, wherein the concavely rounded portion of the outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends to an uppermost part of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

115. The shoe sole as claimed in any one of claims 89-106, wherein the concavely rounded portion of the sole outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends from a lowermost portion of the same sole side to a sidemost extent of the same sole side, as viewed in a frontal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

116. The shoe sole as claimed in any one of claims 89-106, wherein the concavely rounded portion of tine outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends from a sidemost extent of the same sole side to an uppermost part of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

117. The shoe sole as claimed in any one of claims 89-106, wherein the concavely rounded portion of the outer surface of one or more of the heel, midtarsal and forefoot area sole sides extends from the height of the lowest point of the inner surface of a midsole component of the same sole side to an uppermost part of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

118. The shoe sole as claimed in any one of claims 89-117, wherein substantially the entire sole outer surface of the sole midtarsal area is convexly rounded, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the convexity being determined relative to an intended wearer's foot location inside the shoe.

119. The shoe sole as claimed in any one of claims 89-118, wherein at least a portion of the inner surface of a midsole component of the sole midtarsal area is convexly rounded, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the convexity being determined relative to an intended wearer's foot location inside the shoe.

120. The shoe sole as claimed in claim 119, wherein substantially the entire inner surface of a midsole component of the sole midtarsal area is convexly rounded, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

121. The shoe sole as claimed in any one of claims 89-120, wherein the inner surface of a midsole component of the rearmost part of the heel area includes a concavely rounded portion, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the concavity being; determined relative to an intended wearer's foot location inside the shoe.

122. The shoe sole as claimed in any one of claims 89-121, wherein the sole outer surface of the rearmost part of the heel area includes a concavely rounded portion, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an intended wearer's foot location inside the shoe.

123. The shoe sole as claimed in any one of claims 89-122, wherein the inner surface of a midsole component of one or more of the sole heel and forefoot areas includes a concavely rounded portion, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an intended wearer's foot location inside the shoe.

124. The shoe sole as claimed in any one of claims 89-123, wherein the sole outer surface of one or more of the sole heel and forefoot areas includes a concavely rounded portion, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition, the concavity being determined relative to an intended wearer's foot location inside the shoe.

125. The shoe sole as claimed in any one of claims 89-124, wherein an upper part of a midsole component of the rearmost part of the heel area extends up the rear of the heel area to above the height of the lowest point of the inner surface of a midsole component of the rear of the heel area, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

126. The shoe sole as claimed in anyone of claims 89-125 wherein an upper part of a midsole component of a forward part of the sole forefoot area extends above the height of the lowest point of the inner surface of a midsole component in the sole forefoot area, as viewed in a sagittal plane cross-section when the shoe sole is in an upright, unloaded condition.

127. The shoe sole as claimed in any one of claims 89-126, wherein the thickness between the inner surface of the midsole component and the outer surface of the sole tapers by decreasing gradually and substantially continuously on at least one of said heel, midtarsal and forefoot area sole sides from above a sidemost extent of the sole side to the uppermost extent of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

128. The shoe sole as claimed in claim 127, wherein substantially all of the thickness decrease results from the sole outer surface gradually and substantially continuously approaching a centerline of the shoe sole, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

129. The shoe sole as claimed in claim 128, wherein the inner midsole surface from about a sidemost extent of one or more of the heel, midtarsal and forefoot area sole sides to the uppermost extent of the same sole side substantially conforms to the shape of an intended wearer's foot, as viewed in a frontal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

130. The shoe sole as claimed in any one of claims 89-129, wherein the sole has a thickness which is defined as the distance between a first point on the inner surface of the midsole component and a second point on the outer surface of the sole, said second point being located at a point of intersection of the outer surface of the sole and a line perpendicular to a line tangent to the inner midsole surface at said first point on the inner midsole surface.

131. The shoe sole as claimed in any one of claims 89-130, wherein the sole outer surface of the middle sole portion of the sole forefoot area has an indentation. as viewed in the shoe sole frontal plane cross-section during an unloaded, upright shoe condition.

132. The shoe sole as claimed in claim 131, wherein the indentation is substantially convexly rounded, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

133. The shoe sole as claimed in any one of claims 89-132, wherein the inner surface of a midsole component of the middle sole portion of the sole forefoot area has a bulge, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

134. The shoe sole according to claim 133, wherein the bulge is substantially convexly rounded, as viewed in a frontal plane cross-section when the shoe sole is in an upright, unloaded condition.

135. The shoe sole according to any one of claims 89-134, wherein the upper part of a midsole component extends up one or more of the heel, midtarsal and forefoot area sole sides to the height of the sidemost extent of the sole outer surface of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

136. The shoe sole according to any one of claims 89-134, wherein the upper part of a midsole component extends up one or more of the heel, midtarsal and forefoot area sole sides to above the height of the sidemost extent of the sole outer surface of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

137. The shoe sole according to any one of claims 89-134, wherein the upper part of a midsole component extends up one or more of the heel, midtarsal and forefoot area sole sides to proximate to an uppermost part of the same sole side, as viewed in a frontal plane cross-section in one or more of the sole heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

138. The shoe sole as claimed in any one of claims 89-137, wherein the inner midsole surface substantially conforms to the shape of an intended wearer's foot, as viewed in a sagittal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

139. The shoe sole as claimed in anyone of claims 89-138, wherein the inner midsole surface substantially conforms to the shape of an intended wearer's foot, as viewed in a horizontal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

140. The shoe sole as claimed in any one of claims 89-139, wherein the bottom sole surface substantially conforms to the shape of am intended wearer's foot, as viewed in a frontal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

141. The shoe sole as claimed in any one of claims 89-140, wherein the bottom sole surface substantially conforms to the shape of an intended wearer's foot, as viewed in a sagittal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

142. The shoe sole as claimed in any one of claims 89-141, wherein the bottom sole surface substantially conforms to the shape of an intended wearer's foot, as viewed in a horizontal plane cross-section in one or more of the heel, midtarsal and forefoot areas, respectively, when the shoe sole is in an upright, unloaded condition.

143. An athletic sloe sole for supporting a foot of an intended wearer, the shoe sole comprising:
a sole inner surface for supporting the foot of the intended wearer, and a sole outer surface, the sole outer surface having a sole middle portion and at least a sole side adjacent to the sole middle portion;
the sole defining a heel portion at a location substantially corresponding to a calcaneus of the intended wearer's foot, a midtarsal portion at a location substantially corresponding to a midtarsal of the intended wearer's foot, and a forefoot portion at a location substantially corresponding to a forefoot of the intended wearer's foot;
the heel portion having a lateral heel part at a location substantially corresponding to the lateral tuberosity of the calcaneus of the intended wearer's foot, and a medial heel part at a location substantially corresponding to the base of the calcaneus of the intended wearer's foot;
the midtarsal portion being between the forefoot portion and heel portion, and having a lateral midtarsal part at a location substantially corresponding to the base of a fifth metatarsal of the intended wearer's foot, and a main longitudinal arch part at a location substantially corresponding to the longitudinal arch of the intended wearer's foot;
the forefoot portion having a forward medial forefoot part at a location substantially corresponding to the head of the first distal phalange of the intended wearer's foot, and rear medial and lateral forefoot parts at locations substantially corresponding to the heads of the medial and lateral metatarsals of the intended wearer's foot;
the sole further including at least one concavely rounded bulge, as viewed in a shoe sole frontal plane, during a shoe sole unloaded, upright condition, the concavity existing with respect to the intended wearer's foot location in the shoe;
one said concavely rounded bulge being located at the sole side proximate to at least one of the medial heel part, lateral heel part, forward medial forefoot part, rear medial forefoot part, rear lateral forefoot part, lateral midtarsal part, and main longitudinal arch part;
each said at least one concavely rounded bulge including a concavely rounded portion of the inner surface of a midsole component and a concavely rounded portion of the sole outer surface, all as viewed in a shoe sole frontal plane during a shoe sole upright, unloaded condition, the concavity existing with respect to the intended wearer's foot location in the shoe;
the sole including a lateral sidemost section and a medial sidemost section, each section at a location outside of a straight vertical line extending through the shoe sole at a respective sidemost extent of a midsole component inner surface, as viewed in a shoe sole frontal plane cross-section during an unloaded, upright shoe sole condition;
each said at least one concavely rounded bulge includes midsole component extending into the sidemost section of the same sole side as said bulge, as viewed in a sole frontal plane cross-section during an unloaded, upright shoe sole condition;
each said at least one concavely rounded bulge further includes a midsole component upper part extending up said at least one concavely rounded bulge to above a level corresponding to a lowest point of the midsole component inner surface of the same sole side as said bulge, as viewed in a shoe sole frontal plane cross-section during an unloaded, upright shoe sole condition; and the sole outer surface of at least part of the midtarsal portion is substantially convexly rounded, as viewed in a shoe sole sagittal plane cross section during an unloaded, upright shoe sole condition, the convexity existing with respect to an intended wearer's foot location in the shoe;
the concavely rounded portion of the sole outer surface extending through at least a lowermost part of said sole side; and wherein the shoe sole includes at least two said concavely rounded bulges; and a heel portion thickness that is greater than a forefoot portion thickness, as viewed in a shoe sole sagittal plane.

144. A sole according to claim 143, wherein one said concavely rounded bulge is located at the lateral midtarsal part, another said concavely rounded bulge is located at the rear lateral forefoot part, the sole having an indentation between the lateral midtarsal part and rear lateral forefoot part concavely rounded bulges for forming a first flexibility axis in the sole.

145. A sole according to claim 143, wherein one said concavely rounded bulge is located at the lateral heel part, another said concavely rounded bulge is located at the lateral midtarsal part, and an indentation is located between said concavely rounded bulges for forming a flexibility axis in the sole.

146. The shoe sole of claim 143, further including an indentation in the shoe sole adjacent to the one said concavely rounded bulge, as viewed in a shoe sole horizontal plane during a shoe sole upright, unloaded condition.

147. The shoe sole of claim 146, wherein the indentation is a first indentation, and the sole includes a second indentation, such that the first indentation is located anterior to one said concavely rounded bulge and the second indentation is located posterior to one said concavely rounded bulge, all as viewed in a shoe sole horizontal plane during a shoe sole upright, unloaded condition.

148. The shoe sole of claim 146, wherein one said concavely rounded bulge is located at the heel portion of the shoe sole, and the first indentation is located on a lateral side of the shoe sole anterior to the heel portion bulge, and the second indentation is located on a medial side of the shoe sole anterior to the heel portion bulge, all as viewed in a shoe sole horizontal plane.