Note: Descriptions are shown in the official language in which they were submitted.
1340997
:iHOE 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, this 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 levsals. In contrast, such injuries 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 to proposing a
novel solution a<:cordin~3 to 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 l~~ck of control or stability. A popular
existing shoe de;aign incorporates an inverted, outwardly-flared
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shoe sole wherein the around engaging surface is wider than the
heel engaging portion. However, such shoes are unstable 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 rind ankle are destabilized and, in the
extreme, beyond << certa:in 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 grovand. 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 around, 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 st.umblina 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. ids soon as the shoe is tilted,
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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 Izeels only decrease. All existing shoes
continue to decrease the distance all the way down to zero, by
tilting through 50 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 tilted sideways, as
if in effect the shoe: sole were not there except to 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 to maintain a
naturally constant distance during that sideways motion, there are
two possible geometric: solutions, depending upon whether just the
lower horizontal plane of the shoe sole surface varies to achieve
natural contour cr bot.h 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 that 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
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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 foamed by variations in the bottom surface alone.
The upper surf«ce 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 biomech anics. 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 appe;3rance than the two plane solution, but less
biomechanically effective, the one plane quadrant contour side
design is prefs:rable 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 :tear 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 this observation, it can be seen that the
extreme range :;tabil.ity of the conventionally shod foot is
distinctly inferior ~~o the barefoot and that the shoe itself
creates a gross instability which would otherwise not exist.
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Even more important, a normal barefoot running motion,
which approxim~3tely 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
60% 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 hum;3n her=_1 has to pivot within the shoe but is resisted
from doing so b~~ 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 goals 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-bearing portion of the foot sole.
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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 is precisely constant in both side portions and
contoured portions, when measured in frontal plane cross sections,
and therefore biomechanically 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 sole 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 atable shoe 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 supp~~rt and propulsion elements to provide flexibility
and in which tine density of the shoe sole may be increased 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 the shoe which
are consistent with the sole of the foot and are free to move
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independently of each other to follow the motion of the freely
articulating ban.. 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 anothear 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 plane.
It is yet another overall object of this invention to
provide a shoe construction having a design defined by the natural
shape of an unl.oade~i foot and which deforms upon loading to
approximate at least the theoretically ideal stability plane.
It is :>till 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 :;till another object of this invention to provide
a shoe having a ~;ole edge surface which terminates in a laterally
extending portion made: from a flexible material and structured to
terminate upon loading in a position which approximates or is in
parallel with the theoretically ideal stability plane.
It is yet another object of this invention to provide a
shoe with a p:Lural:ity 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 Qf measuring the thickness of shoe sole
contours.
1 340 99 7
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 preci:>e 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 struct=ure 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 then top of the shoe sole.
It is ~jnoth~~r objective of this invention to provide a
sole structure of th.e 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 will another object of this invention to provide
a shoe sole 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 include3 in t:.he structure which defines the theoretically
ideal stability plane.
It is ;till 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 theoretically ideal
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stability plane are applied to the single plane or the 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 conjunci:ion with the accompanying drawings.
Brief Description of the Drawinas
In the drawings:
Fig. 1 is a perspective view of a typical running shoe
known to the prior ari= 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 section 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 tlzickn~ess 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;
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1340997
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 liners 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 cross-sectional view
taken along the heel along lines 7C in Figs. 6 and 7;
Fig. Et is a drawn comparison between a conventional
flared sole show of the prior art and the contoured shoe sole
design according to the invention;
Fig. 5~ 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. 13 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 cro:~s-sectional views showing examples of
conventional soles thickness variations to which the invention can
be applied;
Fig. 1;? 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 truncations 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;
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Fig. 1~E illustrates, in a rear view, an application of
the sole accordS.ng to the invention to a shoe to provide an
aesthetically pleasing and functionally effective design;
Fig. 1!i shows a fully contoured shoe sole design that
follows the natural contour of the bottom of the foot as well as
the sides.
Fig. lE> 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 during 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. lE. 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 ::ole of the invention (Fig. 18B);
Fig. 19 shows the naturally contoured sides 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 alonc3 the sides to only essential structural support
and propulsion e'.~ements;
Fig. 2illustrates 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;
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~34099~
Fig. 2:3 shows a method of establishing the theoretically
ideal stability plane using a perpendicular to a tangent method;
Fig. 2~4 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 :>tability plane according to the invention
during deformation;
Fig. 2f shows an embodiment wherein the contour of the
sole according to the invention is approximated by a plurality of
line segments;
Fig. 2~ 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, in 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
a theoretically ideal stability plane and truncations of the sole
edge quadrant to :reduce shoe bulk;
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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 to the
invention;
Fig. 34 :>hows, 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 tability plane according to the 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. 3F3 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 er~hance~ment to the previously-described embodiment.
Fig. 40 shows, in Figs. 40A - 40C, the enhancement of
Fig. 39 applied t:o thEa 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, a~~cording to the prior art, is shown in Fig. 1
wherein a runnin~~ shoe 20 includes an upper portion 21 and a sole
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~ 340997
22. Typically, ouch 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 thca sole 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 2omm. The rounded portion
lies along appro:Kimately the rear-half of the length of the 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 h 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 a:> 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 (lOD). 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 holding it tightly
and which may a7.so b~e 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
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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 the flared sole
is at a maximum at 0' and only slightly less at a normal 7°
inversion or eve~rsion and thus strongly resists such a natural
motion as is 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 upward:Ly, as discussed later in connection with
Fig. 17.
A narrow rectangular shoe sole design of heel width
approximating human hee:1 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 so7.e 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/ever~;ion 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
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1340997
human foot 2'7 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 correspond exactly to the upper surface 30 of
the shoe sole a:8. The' shoe sole thickness as measured in frontal
plane cross sections is defined as the shortest distance (s)
between any point on t:he upper surface 30 of the shoe sole 28 and
the lower surf;~ce 31 by definition, the surfaces 30 and 31 are
consequently parallel (Figs. 23 and 24 will discuss measurement
methods more fu:Lly). un effect, the applicant's general concept is
a shoe sole 28 that wraps around and conforms to the 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's 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 4C 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 maim feature of the applicant's invention to
eliminate the unnatura:L 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 2ga is contoured like the natural form 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
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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 stabl'.e 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 contou:ced 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 fooi~print, 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 fror,~ 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 sale 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 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 load-bearing portion of
the shoe sole, therefore exclusive of contoured stability sides,
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1340997
should, preferably, coincide as nearly as practicable with the
load-bearing portion oo the foot sole with which it 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 t:he shoe, the' naturally contoured sides 28a
increase in thickness exactly the same amount according 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 ac:cordin<3 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 secaion 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
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1340997
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-secaions '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 cont~~ured sides is equal to the shoe sole thickness in
each Fig. 7A-7<: cross section. Moreover, in Fig. 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 show:z in Fic~. 9A with the extreme tilting situations shown
in Figs. 9B and 9C. Unlike the sharp sole 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 ;hoe sole edge which keeps the foot sole
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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 to 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 Sob closest to
ground lies at a distance (s) from the ground surface 43. That
distance (s) remains <:onstant 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 ba<:k. 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 1=he foot to be protracted 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.
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Fig. l0A i7.lustrates 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 conventional 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 sagittal 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 sides 28a equal and therefore vary with those
varying thicknesses as discussed in connection with Fig. 5.
Fig. 7.2 illu:>trates 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 o!: 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 31a 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 i~heoretically 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 the shoe
sole conforms t:o the natural shape of the wearer's foot sole,
particularly the sides'., and has a constant thickness in frontal
plane cross sections. As shown in Fig. 12B, an engineering trade-
off results
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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 the upper plane
of the shoe sol<~ 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 i~he theoretically ideal stability plane 51.
Figs. 12C and 12;D show similar embodiments wherein each engineering
trade-off shown resu:Lts 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 natu rally 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, i:he added shoe weight to cover that infrequently
experienced range of rnotion 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 lea~~t the maximum of 90° in inversion or eversion, as
shown in Fig. l~;A.
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
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tread portion 60, whilLe Fig. 13B is also similar to Fig. 12B
wherein the sole includes a cleated portion 61. The surface 63 to
which the cleat bases a:re affixed should preferably be on the same
plane and paral:Le1 the: theoretically ideal stability plane 51,
since in soft ground that surface rather than the cleats become
load-bearing. The embodiment in F.ig. 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. 7.4 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 3f. Thus, use of a sole surface and sole outer
contour which track the theoretically ideal stability plane does
not detract from the commercial appeal of shoes incorporating the
invention.
Fig. 1!5 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 rounc9ed 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 oi-.' the shoe sole as well. By providing the
closest match to i:he natural shape of the foot, the fully contoured
design allows the foot to function as naturally as possible. Under
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load, Fig. 15 would deform 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 invention.
Figs. 14 and 15 both show in frontal plane cross section
the essential concept 'underlying this invention, the theoretically
ideal stabilit~t 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 o:E the individual's foot surface 29, to which
the theoretica'_ly ideal stability plane 51 is by definition
parallel.
For the special case shown in Fig. 14, the theoretically
ideal stability plane for 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 th~~ upper surface of the shoe sole that is in
physical contact: with a.nd supports the human foot sole, as shown in
Fig. 4.
The theoreti~~ally ideal stability plane for the special
case is composed conceptually of two parts. Shown in Figs. 14 and
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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 correspor..ds to <~ conventional shoe sole directly underneath
the human foot, and also corresponds to the shoe sole portion 28b
under flattened portion of the bottom of the load-bearing foot
sole. The second part is 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 exactly shoe sole thickness (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 F~recise bottom 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 unequivocally 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 degrade 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
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1~4 ~ ,
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 in the case of Fig. 2. The 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 i.nversion/eversion motion or to destabilize 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. Sihce 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. 26A-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 stability
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, atte~ very much more efficient than the
conventional wide: flare design: at the same time, the contour side
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~34099~
design is more :table ,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 the heel of the foot
27 of the wearer engages an upper s>urface of the shoe sole 22, the
shape of the i_°oot he>el and the shoe sole is such 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/eversi_on 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 nal:ural 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 28 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 and the ground
always the same and therefore completely neutral to the natural
motion of the foot. With the correct basic conception, as
described in connection with this invention, the shoe can move
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1340997
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 ahoe design the cushioning and protection typical
of modern shoes, with the freedom from injury and functional
efficiency, meaning speed, and/or endurance, typical of barefoot
stability and natural. :freedom of motion. Significant speed and
endurance improvements are anticipated, based on both improved
efficiency and en the ability of a user to train harder without
injury.
These figures also illustrate that the shoe heel cannot
pivot plus or minus 7 d~:grees 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, i:n 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 phala.nges (noes). 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 'oottom of the load-bearing foot, with thickness
varying accordin~l to thca heel lift 38. Fig. 19F shows a horizontal
plane top view oi: the left foot that shows the areas 85 of the shoe
sole that correspond to the flattened portions of the foot sole
that are in contact with the ground when load-bearing. Contour
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lines 86 and 87 ..how 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 (not shown) of
Fig. 19F would be the exact reciprocal or converse of Fig. 19F
(i.e. peaks and valleys contours would be exactly reversed).
Figs. 20A-D show, in frontal plane cross sections, the
fully contoured shoe sole design extended to the bottom of the
entire non-load-bearing foot. Fig. 20E shows a sagittal plane
cross section. The shoe sole contours underneath the foot are the
same as Figs. 1.9A-E except that there are no flattened areas
corresponding to the flzittened 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 Fig. 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 ailong the sides to only essential structural
support and propulsion elements. Shoe sole material density can
be increased in t:he unabbreviated essential elements to compensate
for increased pressure loading there. The essential structural
support element:a are the base and lateral tuberosity of the
calcaneus 95, the heads of the metatarsals 96, and the base of the
fifth metatarsal 97. They must be 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) side: 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
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1340997
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 flexibilit~~ improvements can be made by omitting the non-
essential stability sides. Contour lines 85 through 86 show
approximately t:he 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. 27. 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 stability plane
51, as describfad 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 shoran 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 contou~~ed shoe sole design.
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Fig. 23 shows, a method o1: 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 cor,"tour (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 established
at a distance of "s" and that auter edge coincides with the
theoretically ideal stability plane. Both this method and that
described in Fic~. 23 would be used for both manual and CADCAM
design applications.
The shoe sole according t.o the invention can be made by
approximating the contours, as indicated in Figs. 25A, 25B, and 26.
Fig. 25A shows a fronta~Z plane cross section of a design wherein
the sole materi~il in areas 107 is so relatively soft that it
deforms easily t:o the contour of shoe sole 28 of the proposed
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invention. In th,e proposed approximation as seen in Fig. 25B, 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 theoretically
ideal stability F~lane 57.. Sole material in specific areas 107 is
extremely soft to allow :sufficient deformation. Thus, in a dynamic
case, the outer edge contour assumes approximately the theoreti-
cally ideal stability shape described above as a result of the
deformation of the portion 103. The top surface 101 similarly
deforms to approximately parallel the natural contouY 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 second 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 results which are
a significant improvement over conventional designs, they are
inherently inferp.or to contours produced by simple geometric
shaping. First, the <~ctual 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 de;~ign and manufacturing techniques, given an
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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 theoreti<:ally ideal stability plane can also be
approximated by a plurality of line segments 110, such as tangents,
chords, or otheo 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 many correct many of the biomechanical problems
occurring with existing' designs, because it can provide a gross
approximation of the both natural contour of the foot and the
theoretically ideal suability 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 a,_e shown as line segments in the cross section
illustrated in Fig. 26.
Fig. 27 shows a frontal. plane cross section of an
alternate embodiment far 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-hearing shoe sole component 28b would be as
described in Fig. 4). T.he component sides 28a would be a quadrant
of a circle of ra~3it~s (r + r'), where distance (r) must equal sole
thickness (s); consequently the sub-quadrant of radius (r') is
removed from quadrant (r + r'). In geometric terms, the component
- 33 -
1 34p gg 7
side 28a is thus a quarter or other section of a ring. The center
of rotation 115 of the quadrants i.s selected to achieve a sole
upper side surface 30a that closely approximates the natural
contour of the side of t:he 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 a shoe :sole design that allows for
unobstructed natural inversion/eversion motion of the calcaneus by
providing maximum shoe sole flexibility particularly between the
base of the calc;aneus 125 (heel) and the metatarsal heads 126
(forefoot) along an axi:a 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 structural support
elements, the base of then fifth metatarsal 97. An optional support
for the main longitudinal arch 121 may also be retained for runners
with substantial foot p;ronation, although would not be necessary
for many runners. The forefoot can be subdivided (not shown) into
its component esss:ntial :>tructural 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
- 34 -
1 340 gg 7
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 fle:~tibility 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. 2~3A showa 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 simple,
minimalist approach, which is comprised of single frontal plane
slits in the shoe sole material (all layers or part): the first
midway between th,e base of the calcaneus and the base of the fifth
metatarsal, and the second midway between that base and the
metatarsal heads. Fig. 28C shows a bottom view (horizontal plane)
of the inversionjeversion flexibility design.
Fig. 2!3 illustrates in frontal plane cross section a
significant element of 'the applicant's shoe design in its use of
stabilizing quadrants 26 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 rounded shoe sole Badge 25 as shown in Fig. 29. The side or
Trade mark
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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 i:orward or backward. Thus, the side stabilizing
quadrants 26, according to the applicant's invention, are defined
by a radius 25a which is the same as the thickness 34 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 t:he 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 sole 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 surfac~_. Thus, the theoretically ideal stability plane
includes the contours 25 merging into the lower surface 31b of the
sole 28b.
Preferably, th.e peripheral. extent of the sole 36 of the
shoe includes all of the support structures of the foot but extends
no further than the outE:r 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
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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 or positive sole flare so that the sides
are exactly perpendicular to the horizontal plane as shown in Fig.
29B. Preferably, the density of the shoe sole material is uniform.
Another signii'icant feature of the applicant's invention
is illustrated diagrammatically in Fig. 30. Preferably, as the
heel lift or wedgre 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 applicant's
design, the radius 25a of curvature (r) of the side quadrant
is always equal i.o the constant thickness (s) of the shoe sole in
the frontal cross sectional plane.
As shown in Fig. 30B, far 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 oui:er 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 curvature of the
quadrant 26a is equal 'to the thickness sl of the shoe sole 28b
which is thicker than t:he shoe sole (s) shown in Fig. 30A by an
amount equivalent to tlhe heel lift: (s-sl) . In the generalized
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case, the radius (rl) of the quadrant is thus always equal to the
thickness (s) of the shoe sole.
Fig. 37. illustrates how the center of rotation 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 illusitrates 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. Thus, Fid. 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-of.f 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
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stability plane °_.1. Fig. 32C shows a similar embodiment wherein
the engineering tirade-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 example,
a shoe may typically roll out laterally, in an inversion mode, to
about 20 degree on the order of 100 times for each single time it
rolls out to 40 degree. Yet, 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. 3°., in Figs. 33A-33C, shows a development of a
street shoe with a~ contoured sole incorporating the features of the
invention. Fig. ..3A shows a heel cross section of a typical street
shoe 94 having a sole portion 79 arid a heel lift 81. Fig. 33B
develops a theoreticall;r 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 aestheti~~ally 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,
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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 t:he sole of the invention to support the
calcaneal tuberosity. As seen in Fig. 34A, the calcaneal
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 tubero:city, :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 tuberosity 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 wedge 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 i.n the lateral heel area_ to support the
lateral calcaneal tubero;sity. 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 tree shape>. of the calc:aneus and its tuberosity. If
preferred, the wedge can be integrated with and be a part of a
typical contoured heel o:E an insole.
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The shoe sole according to the invention can be made by
approximating the>. contours, as indicated in Figs. 35 and 36. In
the proposed approximation as seers 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 portion 105 is
made from a flexible material and structured to cause its lower
surface 105a to t:erminai=a during deformation at the theoretically
ideal stability ?lane. 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 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 second uses an
easily deformable material in a tapered manner on the sides to
deform under pressure to the correct contour. while sucn
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 parv~icular running gait or body weight. Thus, the
deformation process is limited to a minor effort to correct the
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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 mar corrE~ct 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. E~y incre>.asing the number of flat planar surfaces
formed, the curve more closely approximates exactly the ideal
design contour, as previously described.
Fig. 3'7 showa in frontal plane cross section the
essential concept: underlying this invention, the t=heoretically
ideal stability plane, which is also theoretically ideal for
efficient natural motion of all kinds, including running, jogging
or walking.
For an.y particular individual (or size average of
individuals), tree theoretically ideal stability plane is
determined, first:, by t:he 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 t:he shoe' sole that is in physical contact with and
supports the human foot sole.
The theoretically ideal stability plane is composed
conceptionally of two parts. The first part is a line segment 31b
of equal length and parallel to 3Ub at a constant distance (s)
equal to shoe sole thickness. This corresponds to a conventional
shoe sole directly underneath the human foot. The second part is
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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 (;~), 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 essence 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 c:an be stated unequivocally that any shoe sole
contour, even o~F simi7Lar quadrant contour, that exceeds the
theoretically idE~al stability plane will restrict natural foot
motion, while any lesser contour will degrade natural stability.
That said, iii is possible that an adjustment to a
definition included in i~he 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 to 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 it is possible
that the heel width is t:he 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 footp~~int of the heel. Though not optimal,
narrower heel wi<9th 30b assumptions, even much narrower, may be
used in non-athletic street shoes to obtain a significant propor-
tion of the increases ity stability and efficiency provided by the
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1 340 99 7
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 Lf it can be, not a change in the essential
theoretically ideal stability plane concept claimed in the
invention. Moreover, lthe more narrow the definition, the more
important exact fit becomes and relatively minor individual
misalignments could produce pronation control problems, for
example, that necLate any possible advantage.
Fig. 3B show:> 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 so (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, whi:Le the relatively harder contoured bottom sole
provides good wear for t:he load-bearing areas. Fig. 38B shows in
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a quadrant side design t:he 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 oz- sing le plane design and indicating in Fig. 38D
in the shaded area 129 o:E 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 midsole 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 c:an 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 topologically impossible if all of the side areas
were retained on the boiaom 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 sole 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
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essential to the invention, especially when the very narrow or
"hard tissue" dei:inition of heel width is used. Incorrect or
shifting relative position will reduce the inherent efficiency and
stability of the side c~aadrant design, by reducing the effective
thickness of the quadrant side 26 to less than that of the shoe
sole 28b. As shown in Fp.g. 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 26 when the shoe is everted or inverted,
following the theoretically ideal stability plane 51.
The for~r of th~a enhancement is inner shoe sole stability
sides 131 that follow the natural contour of the sidhs 91 of the
heel of the foot 90, thereby cupping the heel of the foot. The
inner stability sides :L31 can be located directly on the top
surface of the shoe sols~ and heel contour, or directly under the
shoe insole (or integral to it), or somewhere in between. The
inner stability sides are similar in structure to 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 so:Et 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 th~~ hroa~dest 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
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1 340 gg 7
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 impo~~tant 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 t:he upper edge of t:he heel of the shoe sole 27,
but may also be e~aended around all ar 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 it applies
to the previously described 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 t=he naturally contoured sides 28a design, as shown
in Figs. 408 and 4oC; 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). The other
features of the enhancement as it applies to the naturally
contoured shoe sole sides embodiment 28 are the same as described
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1340997
previously under Figs. 39A-39C for the side stability quadrant
embodiment. It i;s clear from comparing Figs. 40C and 39C that the
two different apF~roache::, 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 ap~~roache:a provide a low cost or interim method of
adapting existing conventional "flat sheet" shoe manufacturing to
the naturally contoured design described in previous figures.
Thus, it will clearly be understood by those skilled 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 :>cope of the present invention
which is to be defined k>y the appen<9ed claims.
_ 4g ._
