U.S. patent application number 09/780450 was filed with the patent office on 2002-01-24 for shoe sole structure having midsole sides.
Invention is credited to Ellis, Frampton E. III.
Application Number | 20020007572 09/780450 |
Document ID | / |
Family ID | 23584706 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007572 |
Kind Code |
A1 |
Ellis, Frampton E. III |
January 24, 2002 |
Shoe sole structure having midsole sides
Abstract
A shoe sole having at least one midsole or outer surface portion
that is concavely rounded relative to a space inside the shoe
adapted to receive an intended wearer's foot. The sole includes a
midsole and an outer sole. The midsole extends up the side of the
sole to a vertical height above the vertical height of a lowest
point of the inner midsole surface. The midsole includes a portion
of greatest thickness in a side portion that is greater than a
thickness of a second midsole portion located in a middle sole
portion of the shoe sole. The combination of the midsole height and
thickness with the concavely rounded surface portion together
provide improved stability of the shoe sole.
Inventors: |
Ellis, Frampton E. III;
(Arlington, VA) |
Correspondence
Address: |
Ronal P. Kananen
Jorys, Sater, Seymour & Pease
Suite 1111
1828 L Street, N.W.
Washington
DC
20036
US
|
Family ID: |
23584706 |
Appl. No.: |
09/780450 |
Filed: |
February 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09780450 |
Feb 12, 2001 |
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09710952 |
Nov 14, 2000 |
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09710952 |
Nov 14, 2000 |
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08376661 |
Jan 23, 1995 |
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08376661 |
Jan 23, 1995 |
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08127487 |
Sep 28, 1993 |
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08127487 |
Sep 28, 1993 |
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07729886 |
Jul 11, 1991 |
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07729886 |
Jul 11, 1991 |
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07400714 |
Aug 30, 1989 |
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Current U.S.
Class: |
36/114 ; 36/28;
36/30R |
Current CPC
Class: |
A43B 13/145 20130101;
A43B 13/146 20130101; A43B 13/143 20130101; A43B 13/148
20130101 |
Class at
Publication: |
36/114 ; 36/28;
36/30.00R |
International
Class: |
A43B 005/00; A43B
013/12 |
Claims
1. A shoe sole for a shoe, said shoe sole comprising: a sole
lateral side, a sole medial side, and a sole middle portion located
between the sole lateral and medial sides; a midsole having an
inner midsole surface and an outer midsole surface, the midsole
including a first midsole portion located in one of said sole
sides, and a second midsole portion located in the middle sole
portion; the sole lateral side comprising a lateral sidemost
section located outside of a vertical line drawn at the sidemost
extent of the inner midsole surface; the sole medial side
comprising a medial sidemost section located outside of a vertical
line drawn at the sidemost extent of the inner midsole surface; an
outer sole; the outer midsole surface of the first midsole portion
extends up the sole side to a vertical height above a vertical
height of a lowest point of the inner midsole surface, as viewed in
a frontal plane cross-section when the shoe sole is in an upright,
unloaded condition; the first midsole portion having a greatest
thickness measured between the inner and outer midsole surfaces of
the first midsole portion, that is greater than a thickness
measured between the inner and outer midsole surfaces of the second
midsole portion, as viewed in a frontal plane cross-section when
the shoe sole is in an upright, unloaded condition; and the outer
midsole surface of the first midsole portion comprises a lowermost
portion that 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.
2. A shoe sole as claimed in claim 1, wherein the inner midsole
surface further comprises a portion that 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.
3. A shoe sole as claimed in claim 1, wherein the concavely rounded
portion of the outer midsole surface extends to a 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.
4. A shoe sole as claimed in claim 1, wherein the outer midsole
surface of the first midsole portion is concavely rounded relative
to an intended wearer's foot location inside the shoe 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: a base of the
calcaneus, a lateral tuberosity of the calcaneus, a head of the
first distal phalange, a head of the first metatarsal, a base of
the fifth metatarsal, a head of the fifth metatarsal, and a main
longitudinal arch, as viewed in a frontal plane cross-section at
said one or more locations when the shoe sole is in an upright,
unloaded condition.
5. A shoe sole as claimed in claim 1, wherein the outer sole
extends to a sidemost section of the shoe sole; and at least a
portion of the outer surface of the outer sole located in the
sidemost section 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.
6. A shoe sole as claimed in claim 1, wherein the thickness is
defined as the shortest distance between a point on the inner
surface of the midsole and the closest point on the outer midsole
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 claim 1, 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.
8. A shoe sole as claimed in claim 1, wherein the outer midsole
surface of the at least one portion of the midsole located in the
sole middle portion is substantially flat, 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 claim 1, wherein the outer midsole
surface of the at least one portion of the midsole located in the
sole middle portion 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.
10. A shoe sole as claimed in claim 1, 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.
11. A shoe sole as claimed in claim 1, wherein the thickness of the
shoe sole varies, as viewed in a sagittal plane when the shoe sole
is in an upright, unloaded condition.
12. A shoe sole for a shoe, said shoe sole comprising: a sole inner
surface and a sole outer surface; a sole lateral side defined by
the sole inner and outer surfaces; a sole medial side defined by
the sole inner and outer surfaces; a sole middle portion located
between the sole lateral and medial sides and defined by the sole
inner and outer surfaces; a midsole having an inner midsole surface
and an outer midsole surface, the midsole including a first midsole
portion located in one of said sole sides, and a second midsole
portion located in the middle sole portion; an outer sole; the
outer midsole surface of the first midsole portion extends up the
sole side to a vertical height above a vertical height of a lowest
point of the inner midsole surface, as viewed in a frontal plane
cross-section when the shoe sole is in an upright, unloaded
condition; the first midsole portion having a greatest thickness
measured between the inner and outer midsole surfaces of the first
midsole portion, that is greater than a thickness measured between
the inner and outer midsole surfaces of the second midsole portion,
as viewed in a frontal plane cross-section when the shoe sole is in
an upright, unloaded condition; and the sole outer surface
comprises a lowermost portion that 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.
13. A shoe sole as claimed in claim 12, wherein the inner midsole
surface further comprises a portion that 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.
14. A shoe sole as claimed in claim 12, wherein the concavely
rounded portion of the outer midsole surface extends to a 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.
15. A shoe sole as claimed in claim 12, wherein the outer midsole
surface of the first midsole portion is concavely rounded relative
to an intended wearer's foot location inside the shoe 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: a base of the
calcaneus, a lateral tuberosity of the calcaneus, a head of the
first distal phalange, a head of the first metatarsal, a base of
the fifth metatarsal, a head of the fifth metatarsal, and a main
longitudinal arch, as viewed in a frontal plane cross-section at
said one or more locations when the shoe sole is in an upright,
unloaded condition.
16. A shoe sole as claimed in claim 12, wherein the outer sole
extends to a sidemost section of the shoe sole; and at least a
portion of the outer surface of the outer sole located in the
sidemost section 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.
17. A shoe sole as claimed in claim 12, wherein the thickness is
defined as the shortest distance between a point on the inner
surface of the midsole and the closest point on 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 claim 12, 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.
19. A shoe sole as claimed in claim 12, wherein the outer midsole
surface of the at least one portion of the midsole located in the
sole middle portion 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.
20. A shoe sole as claimed in claim 12, 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.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to the structure of shoes.
More specifically, this invention relates to the structure of
running shoes. Still more particularly, this invention relates to
variations in the structure of such shoes using a
theoretically-ideal stability plane as a basic concept.
[0002] Existing running shoes are unnecessarily unsafe. They
profoundly disrupt natural human biomechanics. The resulting
unnatural foot and ankle motion leads to what are abnormally high
levels of running injuries.
[0003] Proof of the unnatural effect of shoes has come quite
unexpectedly from the discovery that, at the extreme end of its
normal range of motion, the unshod bare foot is naturally stable,
almost unsprainable, while the foot equipped with any shoe,
athletic or otherwise, is artificially unstable and abnormally
prone to ankle sprains. Consequently, ordinary ankle sprains must
be viewed as largely an unnatural phenomena, even though fairly
common. Compelling evidence demonstrates that the stability of bare
feet is entirely different from the stability of shoe-equipped
feet.
[0004] The underlying cause of the universal instability of shoes
is a critical but correctable design flaw. That hidden flaw, so
deeply ingrained in existing shoe designs, is so extraordinarily
fundamental that it has remained unnoticed until now. The flaw is
revealed by a novel new biomechanical test, one that is
unprecedented in its simplicity. It is easy enough to be duplicated
and verified by anyone; it only takes a few minutes and requires no
scientific equipment or expertise. The simplicity of the test
belies its surprisingly convincing results. It demonstrates an
obvious difference in stability between a bare foot and a running
shoe, a difference so unexpectedly huge that it makes an apparently
subjective test clearly objective instead. The test proves beyond
doubt that all existing shoes are unsafely unstable.
[0005] The broader implications of this uniquely unambiguous
discovery are potentially far-reaching. The same fundamental flaw
in existing shoes that is glaringly exposed by the new test also
appears to be the major cause of chronic overuse injuries, which
are unusually common in running, as well as other sport injuries.
It causes the chronic injuries in the same way it causes ankle
sprains; that is, by seriously disrupting natural foot and ankle
biomechanics.
[0006] The applicant has introduced into the art the concept of a
theoretically ideal stability plane as a structural basis for shoe
designs. That concept as implemented into shoes such as street
shoes and athletic shoes is presented in pending U.S. applications
Ser. Nos. 07/219,387, filed on Jul. 15, 1988 and 07/239,667, filed
on Sep. 2, 1988, as well as in PCT Application No. PCT/US89/03076
filed on Jul. 14, 1989. This application develops the application
of the concept of the theoretically ideal stability plane to other
shoe structures and presents certain structural ideas presented in
the PCT application.
[0007] Accordingly, it is a general object of this invention to
elaborate upon the application of the principle of the
theoretically ideal stability plane to other shoe structures.
[0008] It is another general object of this invention to provide a
shoe sole which, when under load and tilting to the side, deforms
in a manner which closely parallels that of the foot of its wearer,
while retaining nearly the same amount of contact of the shoe sole
with the ground as in its upright state.
[0009] It is still another object of this invention to provide a
deformable shoe sole having the upper portion or the sides bent
inwardly somewhat so that when worn the sides bend out easily to
approximate a custom fit.
[0010] It is still another object of this invention to provide a
shoe having a naturally contoured sole which is abbreviated along
its sides to only essential structural stability and propulsion
elements, which are combined and integrated into the same
discontinuous shoe sole structural elements underneath the foot,
which approximate the principal structural elements of a human foot
and their natural articulation between elements.
[0011] These and other objects of the invention will become
apparent from a detailed description of the invention which follows
taken with the accompanying drawings.
BRIEF SUMMARY OF THE INVENTION
[0012] Directed to achieving the aforementioned objects and to
overcoming problems with prior art shoes, a shoe according to the
invention comprises a sole having at least a portion thereof
following the contour of a theoretically ideal stability plane, and
which further includes rounded edges at the finishing edge of the
sole after the last point where the constant shoe sole thickness is
maintained. Thus, the upper surface of the sole does not provide an
unsupported portion that creates a destabilizing torque and the
bottom surface does not provide an unnatural pivoting edge.
[0013] In another aspect, the shoe includes a naturally contoured
sole structure exhibiting natural deformation which closely
parallels the natural deformation of a foot under the same load. In
a preferred embodiment, the naturally contoured side portion of the
sole extends to contours underneath the load-bearing foot. In
another embodiment, the sole portion is abbreviated along its sides
to essential support and propulsion elements wherein those elements
are combined and integrated into the same discontinuous shoe sole
structural elements underneath the foot, which approximate the
principal structural elements of a human foot and their natural
articulation between elements. The density of the abbreviated shoe
sole can be greater than the density of the material used in an
unabbreviated shoe sole to compensate for increased pressure
loading. The essential support elements include the base and
lateral tuberosity of the calcaneus, heads of the metatarsal, and
the base of the fifth metatarsal.
[0014] The shoe sole is naturally contoured, paralleling the shape
of the foot in order to parallel its natural deformation, and made
from a material which, when under load and tilting to the side,
deforms in a manner which closely parallels that of the foot of its
wearer, while retaining nearly the same amount of contact of the
shoe sole with the ground as in its upright state under load. A
deformable shoe sole according to the invention may have its sides
bent inwardly somewhat so that when worn the sides bend out easily
to approximate a custom fit.
[0015] These and other features of the invention will become
apparent from the detailed description of the invention which
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the drawings:
[0017] FIG. 1 is a rear view of a heel of a foot for explaining the
use of a stationery sprain simulation test.
[0018] FIG. 2 is a rear view of a conventional running shoe
unstably rotating about an edge of its sole when the shoe sole is
tilted to the outside.
[0019] FIG. 3 is a diagram of the forces on a foot when rotating in
a shoe of the type shown in FIG. 2.
[0020] FIG. 4 is a view similar to FIG. 3 but showing further
continued rotation of a foot in a shoe of the type shown in FIG.
2.
[0021] FIG. 5 is a force diagram during rotation of a shoe having
motion control devices and heel counters.
[0022] FIG. 6 is another force diagram during rotation of a shoe
having a constant shoe sole thickness, but producing a
destabilizing torque because a portion of the upper sole surface is
unsupported during rotation.
[0023] FIG. 7 shows an approach for minimizing destabilizing torque
by providing only direct structural support and by rounding edges
of the sole and its outer and inner surfaces.
[0024] FIGS. 8A to 8I illustrate functionally the principles of
natural deformation as applied to the shoe soles of the
invention.
[0025] FIG. 9 shows variations in the relative density of the shoe
sole including the shoe insole to maximize an ability of the sole
to deform naturally.
[0026] FIG. 10 shows a shoe having naturally contoured sides bent
inwardly somewhat from a normal size so then when worn the shoe
approximates a custom fit.
[0027] FIG. 11 shows a shoe sole having a fully contoured design
but having sides which are abbreviated to the essential structural
stability and propulsion elements that are combined and integrated
into discontinuous structural elements underneath the foot that
simulate those of the foot.
[0028] FIG. 12 is a diagram serving as a basis for an expanded
discussion of a correct approach for measuring shoe sole
thickness.
[0029] FIG. 13 shows an embodiment of the invention in a shoe sole
wherein only the outer or bottom sole includes the special contours
of the design of the invention and maintains a conventional flat
upper surface to ease joining with a conventional flat midsole
lower surface.
[0030] FIG. 14 shows in frontal plane cross sections an inner shoe
sole enhancement to the previously described embodiments of the
show sole side stability quadrant invention.
[0031] FIG. 15 shows in frontal plane cross sections an inner shoe
sole stability side enhancement applied to the previously described
embodiments of the naturally contoured sides design.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 shows in a real illustration a foot 27 in position
for a new biomechanical test that is the basis for the discovery
that ankle sprains are in fact unnatural for the bare foot. The
test simulates a lateral ankle sprain, where the foot 27--on the
ground 43--rolls or tilts to the outside, to the extreme end of its
normal range of motion, which is usually about 20 degrees at the
heel 29, as shown in a rear view of a bare (right) heel in FIG. 1.
Lateral (inversion) sprains are the most common ankle sprains,
accounting for about three-fourths of all.
[0033] The especially novel aspect of the testing approach is to
perform the ankle spraining simulation while standing stationary.
The absence of forward motion is the key to the dramatic success of
the test because otherwise it is impossible to recreate for testing
purposes the actual foot and ankle motion that occurs during a
lateral ankle sprain, And simultaneously to do it in a controlled
manner, while at normal running speed or even jogging slowly, or
walking. Without the critical control achieved by slowing forward
motion all the way down to zero, any test subject would end up with
a sprained ankle.
[0034] That is because actual running in the real world is dynamic
and involves a repetitive force maximum of three times one's full
body weight for each footstep, with sudden peaks up to roughly five
or six times for quick stops, missteps, and direction changes, as
might be experienced when spraining an ankle. In contrast, in the
static simulation test, the forces are tightly controlled and
moderate, ranging from no force at all up to whatever maximum
amount that is comfortable.
[0035] The Stationary Sprain Simulation Test (SSST) consists simply
of standing stationary with one foot bare and the other shod with
any shoe. Each foot alternately is carefully tilted to the outside
up to the extreme end of its range of motion, simulating a lateral
ankle sprain.
[0036] The Stationary Sprain Simulation Test clearly identifies
what can be no less than a fundamental flaw in existing shoe
design. It demonstrates conclusively that nature's biomechanical
system, the bare foot, is far superior in stability to man's
artificial shoe design. Unfortunately, it also demonstrates that
the shoe's severe instability overpowers the natural stability of
the human foot and synthetically creates a combined biomechanical
system that is artificially unstable. The shoe is the weak
link.
[0037] The test shows that the bare foot is inherently stable at
the approximate 20 degree end of normal joint range because of the
wide, steady foundation the bare heel 29 provides the ankle joint,
as seen in FIG. 1. In fact, the area of physical contact of the
bare heel 29 with the ground 43 is not much less when tilted all
the way out to 20 degrees as when upright at 0 degrees.
[0038] The new Stationary Sprain Simulation Test provides a natural
yardstick, totally missing until now, to determine whether any
given shoe allows the foot within it to function naturally. If a
shoe cannot pass this simple litmus test, it is positive proof that
a particular shoe is interfering with natural foot and ankle
biomechanics. The only question is the exact extent of the
interference beyond that demonstrated by the new test.
[0039] Conversely, the applicant's designs are the only designs
with shoe soles thick enough to provide cushioning (thin-soled and
heel-less moccasins do pass the test, but do not provide cushioning
and only moderate protection) that will provide naturally stable
performance, like the bare foot, in the Stationary Sprain
Simulation Test.
[0040] FIG. 2 shows that, in complete contrast, the foot equipped
with a conventional running shoe, designated generally by the
reference numeral 20 and having an upper 21, though initially very
stable while resting completely flat on the ground, becomes
immediately unstable when the shoe sole 22 is tilted to the
outside. The tilting motion lifts from contact with the ground all
of the shoe sole 22 except the artificially sharp edge of the
bottom outside corner. The shoe sole instability increases the
farther the foot is rolled laterally. Eventually; the instability
induced by the shoe itself is so great that the normal load-bearing
pressure of full body weight would actively force an ankle sprain
if not controlled. The abnormal tilting motion of the shoe does not
stop at the barefoot's natural 20 degree limit, as you can see from
the 45 degree tilt of the shoe heel in FIG. 2.
[0041] That continued outward rotation of the shoe past 20 degrees
causes the foot to slip within the shoe, shifting its position
within the shoe to the outside edge, further increasing the shoe's
structural instability. The slipping of the foot within the shoe is
caused by the natural tendency of the foot to slide down the
typically flat surface of the tilted shoe sole; the more the tilt,
the stronger the tendency. The heel is shown in FIG. 2 because of
its primary importance in sprains due to its direct physical
connection to the ankle ligaments that are torn in an ankle sprain
and also because of the heel's predominant role within the foot in
bearing body weight.
[0042] It is easy to see in the two figures how totally different
the physical shape of the natural bare foot is compared to the
shape of the artificial shoe sole. It is strikingly odd that the
two objects, which apparently both have the same biomechanical
function, have completely different physical shapes. Moreover, the
shoe sole clearly does not deform the same way the human foot sole
does, primarily as a consequence of its dissimilar shape.
[0043] FIG. 3A illustrates that the underlying problem with
existing shoe designs is fairly easy to understand by looking
closely at the principal forces acting on the physical structure of
the shoe sole. When the shoe is tilted outwardly, the weight of the
body held in the shoe upper 21 shifts automatically to the outside
edge of the shoe sole 22. But, strictly due to its unnatural shape,
the tilted shoe sole 22 provides absolutely no supporting physical
structure directly underneath the shifted body weight where it is
critically needed to support that weight. An essential part of the
supporting foundation is missing. The only actual structural
support comes from the sharp corner edge 23 of the shoe sole 22,
which unfortunately is not directly under the force of the body
weight after the shoe is tilted. Instead, the corner edge 23 is
offset well to the inside.
[0044] As a result of that unnatural misalignment, a lever arm 23a
is set up through the shoe sole 22 between two interacting forces
(called a force couple): the force of gravity on the body (usually
known as body weight 133) applied at the point 24 in the upper 21
and the reaction force 134 of the ground, equal to and opposite to
body weight when the shoe is upright. The force couple creates a
force moment, commonly called torque, that forces the shoe 20 to
rotate to the outside around the sharp corner edge 23 of the bottom
sole 22, which serves as a stationary pivoting point 23 or center
of rotation.
[0045] Unbalanced by the unnatural geometry of the shoe sole when
tilted, the opposing two forces produce torque, causing the shoe 20
to tilt even more. As the shoe 20 tilts further, the torque forcing
the rotation becomes even more powerful, so the tilting process
becomes a self-reenforcing cycle. The more the shoe tilts, the more
destabilizing torque is produced to further increase the tilt.
[0046] The problem may be easier to understand by looking at the
diagram of the force components of body weight shown in FIG. 3A.
When the shoe sole 22 is tilted out 45 degrees, as shown, only half
of the downward force of body weight 133 is physically supported by
the shoe sole 22; the supported force component 135 is 71% of full
body weight 133. The other half of the body weight at the 45 degree
tilt is unsupported physically by any shoe sole structure; the
unsupported component is also 71% of full body weight 133. It
therefore produces strong destabilizing outward tilting rotation,
which is resisted by nothing structural except the lateral
ligaments of the ankle.
[0047] FIG. 3B show that the full force of body weight 133 is split
at 45 degrees of tilt into two equal components: supported 135 and
unsupported 136, each equal to 0.707 of full body weight 133. The
two vertical components 137 and 138 of body weight 133 are both
equal to 0.50 of full body weight. The ground reaction force 134 is
equal to the vertical component 137 of the supported component
135.
[0048] FIG. 4 show a summary of the force components at shoe sole
tilts of 0, 45 and 90 degrees. FIG. 4, which uses the same
reference numerals as in FIG. 3, shows that, as the outward
rotation continues to 90 degrees, and the foot slips within the
shoe while ligaments stretch and/or break, the destabilizing
unsupported force component 136 continues to grow. When the shoe
sole has tilted all the way out to 90 degrees (which unfortunately
does happen in the real world), the sole 22 is providing no
structural support and there is no supported force component 135 of
the full body weight 133. The ground reaction force at the pivoting
point 23 is zero, since it would move to the upper edge 24 of the
shoe sole.
[0049] At that point of 90 degree tilt, all of the full body weight
133 is directed into the unresisted and unsupported force component
136, which is destabilizing the shoe sole very powerfully. In other
words, the full weight of the body is physically unsupported and
therefore powering the outward rotation of the shoe sole that
produces an ankle sprain. Insidiously, the farther ankle ligaments
are stretched, the greater the force on them.
[0050] In stark contrast, untilted at 0 degrees, when the shoe sole
is upright, resting flat on the ground, all of the force of body
weight 133 is physically supported directly by the shoe sole and
therefore exactly equals the supported force component 135, as also
shown in FIG. 4. In the untilted position, there is no
destabilizing unsupported force component 136.
[0051] FIG. 5 illustrates that the extremely rigid heel counter 141
typical of existing athletic shoes, together with the motion
control device 142 that are often used to strongly reinforce those
heel counters (and sometimes also the sides of the mid- and
forefoot), are ironically counterproductive. Though they are
intended to increase stability, in fact they decrease it. FIG. 5
shows that when the shoe 20 is tilted out, the foot is shifted
within the upper 21 naturally against the rigid structure of the
typical motion control device 142, instead of only the outside edge
of the shoe sole 22 itself. The motion control support 142
increases by almost twice the effective lever arm 132 (compared to
23a) between the force couple of body weight and the ground
reaction force at the pivot point 23. It doubles the destabilizing
torque and also increases the effective angle of tilt so that the
destabilizing force component 136 becomes greater compared to the
supported component 135, also increasing the destabilizing torque.
To the extent the foot shifts further to the outside, the problem
becomes worse. Only by removing the heel counter 141 and the motion
control devices 142 can the extension of the destabilizing lever
arm be avoided. Such an approach would primarily rely on the
applicant's contoured shoe sole to "cup" the foot (especially the
heel), and to a much lesser extent the non-rigid fabric or other
flexible material of the upper 21, to position the foot, including
the heel, on the shoe. Essentially, the naturally contoured sides
of the applicant's shoe sole replace the counter-productive
existing heel counters and motion control devices, including those
which extend around virtually all of the edge of the foot.
[0052] FIG. 6 shows that the same kind of torsional problem, though
to a much more moderate extent, can be produced in the applicant's
naturally contoured design of the applicant's earlier-filed
applications. There, the concept of a theoretically-ideal stability
plane was developed in terms of a sole 28 having a lower surface 31
and an upper surface 30 which are spaced apart by a predetermined
distance which remains constant throughout the sagittal frontal
planes. The outer surface 27 of the foot is in contact with the
upper surface 30 of the sole 28. Though it might seem desireable to
extend the inner surface 30 of the shoe sole 28 up around the sides
of the foot 27 to further support it (especially in creating
anthropomorphic designs), FIG. 6 indicates that only that portion
of the inner shoe sole 28 that is directly supported structurally
underneath by the rest of the shoe sole is effective in providing
natural support and stability. Any point on the upper surface 30 of
the shoe sole 28 that is not supported directly by the constant
shoe sole thickness (as measured by a perpendicular to a tangent at
that point and shown in the shaded area 143) will tend to produce a
moderate destabilizing torque. To avoid creating a destabilizing
lever arm 132, only the supported contour sides and non-rigid
fabric or other material can be used to position the foot on the
shoe sole 28.
[0053] FIG. 7 illustrates an approach to minimize structurally the
destabilizing lever arm 32 and therefore the potential torque
problem. After the last point where the constant shoe sole
thickness (s) is maintained, the finishing edge of the shoe sole 28
should be tapered gradually inward from both the top surface 30 and
the bottom surface 31, in order to provide matching rounded or
semi-rounded edges. In that way, the upper surface 30 does not
provide an unsupported portion that creates a destabilizing torque
and the bottom surface 31 does not provide an unnatural pivoting
edge. The gap 144 between shoe sole 28 and foot sole 29 at the edge
of the shoe sole can be "caulked" with exceptionally soft sole
material as indicated in FIG. 7 that, in the aggregate (i.e. all
the way around the edge of the shoe sole), will help position the
foot in the shoe sole. However, at any point of pressure when the
shoe tilts, it will deform easily so as not to form an unnatural
lever causing a destabilizing torque.
[0054] FIGS. 8A-8C illustrate clearly the principle of natural
deformation as it applies to the applicant's design, even though
design diagrams like those preceding (and in his previous
applications already referenced) are normally shown in an ideal
state, without any functional deformation, obviously to show their
exact shape for proper construction. That natural structural shape,
with its contour paralleling the foot, enables the shoe sole to
deform naturally like the foot. In the applicant's invention, the
natural deformation feature creates such an important functional
advantage it will be illustrated and discussed here fully. Note in
the figures that even when the shoe sole shape is deformed, the
constant shoe sole thickness in the frontal plane feature of the
invention is maintained.
[0055] FIG. 8A shows upright, unloaded and therefore undeformed the
fully contoured shoe sole design indicated in FIG. 15 of U.S.
patent application Ser. No. 07/239,667 (filed Sep. 2, 1988). FIG.
8A shows a fully contoured shoe sole design that follows the
natural contour of all of the foot sole, 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 as
shown in FIG. 8B and flatten just as the human foot bottom is
slightly rounded unloaded but flattens under load. Therefore, the
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 closes match to the natural shape of the foot, the
fully contoured design allows the foot to function as naturally as
possible. Under load, FIG. 8A would deform by flattening to look
essentially like FIG. 8B.
[0056] FIGS. 8A and 8B 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. 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.
[0057] For the case shown in FIG. 8B, 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 which is
defined as the supper surface of the shoe sole that is in physical
contact with and supports the human foot sole.
[0058] FIG. 8B shows the same fully contoured design when upright,
under normal load (body weight) and therefore deformed naturally in
a manner very closely paralleling the natural deformation under the
same load of the foot. An almost identical portion of the foot sole
that is flattened in deformation is also flattened in deformation
in the shoe sole. FIG. 8C shows the same design when tilted outward
20 degrees laterally, the normal barefoot limit; with virtually
equal accuracy it shows the opposite foot tilted 20 degrees inward,
in fairly severe pronation. As shown, the deformation of the shoe
sole 28 again very closely parallels that of the foot, even as it
tilts. Just as the area of foot contact is almost as great when
tilted 20 degrees, the flattened area of the deformed shoe sole is
also nearly the same as when upright. Consequently, the barefoot is
fully supported structurally and its natural stability is
maintained undiminished, regardless of shoe tilt. In marked
contrast, a conventional shoe, shown in FIG. 2, makes contact with
the ground with only its relatively sharp edge when tilted and is
therefore inherently unstable.
[0059] The capability to deform naturally is a design feature of
the applicant's naturally contoured shoe sole designs, whether
fully contoured or contoured only at the sides, though the fully
contoured design is most optimal and is the most natural, general
case, as note in the referenced Sep. 2, 1988, application, assuming
shoe sole material such as to allow natural deformation. It is an
important feature because, by following the natural deformation of
the human foot, the naturally deforming shoe sole can avoid
interfering with the natural biomechanics of the foot and
ankle.
[0060] FIG. 8C also represents with reasonable accuracy a shoe sole
design corresponding to FIG. 8B, a naturally contoured shoe sole
with a conventional built-in flattening deformation, as in FIG. 14
of the above referenced Sep. 2, 1988, application, except that
design would have a slight crimp at 145. Seen in this light, the
naturally contoured side design in FIG. 8B is a more conventional,
conservative design that is a special case of the more generally
fully contoured design in FIG. 8A, which is the closest to the
natural form of the foot, but the least conventional.
[0061] FIGS. 8D-8F show a stop action sequence of the applicant's
fully contoured shoe sole during the normal landing and support
phases of running to demonstrate the normal functioning of the
natural deformation feature. FIG. 8D shows the foot and shoe
landing in a normal 10 degree inversion position; FIG. 8E shows the
foot and shoe after they have rolled to an upright position; and
FIG. 8F shows them having rolled inward 10 degrees in eversion, a
normal pronation maximum. The sequence of figures illustrate
clearly the natural deformation of the applicant's shoe sole design
follows that of the foot very closely so that both provide a nearly
equal flattened base to stabilize the foot. Comparing those figures
to the same action sequence of FIGS. 8G-8I for conventional shoes
illustrates clearly how unnatural the basic design of existing
shoes is, since a smooth inward rolling motion is impossible for
the flat, uncontoured shoe sole, and rolling of the foot within the
shoe is resisted by the heel counter. In short, the convention shoe
interferes with the natural inward motion of the foot during the
critical landing and support phases of running.
[0062] FIG. 9 shows the preferred relative density of the shoe
sole, including the insole as a part, in order to maximize the shoe
sole's ability to deform naturally following the natural
deformation of the foot sole. Regardless of how many shoe sole
layers (including insole) or laminations of differing material
densities and flexibility are used in total, the softest and most
flexible material 147 should be closest to the foot sole, with a
progression through less soft 148 to the firmest and least flexible
149 at the outermost shoe sole layer, the bottom sole. This
arrangement helps to avoid the unnatural side lever arm/torque
problem mentioned in the previous several figures. That problem is
most severe when the shoe sole is relatively hard and non-deforming
uniformly throughout the shoe sole, like most conventional street
shoes, since hard material transmits the destabilizing torque most
effectively by providing a rigid lever arm.
[0063] The relative density shown in FIG. 9 also helps to allow the
shoe sole to duplicate the same kind of natural deformation
exhibited by the bare foot sole in FIG. 1, since the shoe sole
layers closest to the foot, and therefore with the most severe
contours, have to deform the most in order to flatten like the
barefoot and consequently need to be soft to do so easily. This
shoe sole arrangement also replicates roughly the natural barefoot,
which is covered with a very tough "seri boot" outer surface
(protecting a softer cushioning interior of fat pads) among
primitive barefoot populations.
[0064] Finally, the use of natural relative density as indicated in
this figure will allow more anthropomorphic embodiments of the
applicant's designs (right and left sides of FIG. 9 show variations
of different degrees) with sides going higher around the side
contour of the foot and thereby blending more naturally with the
sides of the foot, since those conforming sides will not be
effective as destabilizing lever arms because the shoe sole
material there would be soft and unresponsive in transmitting
torque, since the lever arm will bend. For example, the portion
near the foot of the shaded edge area 143 in FIG. 6 must be
relatively soft so as not to provide a destabilizing lever arm.
[0065] As a point of clarification, the forgoing principle of
preferred relative density refers to proximity to the foot and is
not inconsistent with the term uniform density as used in U.S.
patent application Ser. Nos. 07/219,387 filed Jul. 15, 1988 and
07/239,667 filed Sep. 2, 1988. Uniform shoe sole density is
preferred strictly in the sense of preserving even and natural
support to the foot like the ground provides, so that a neutral
starting point can be established, against which so-called
improvements can be measured. The preferred uniform density is in
marked contrast to the common practice in athletic shoes today,
especially those beyond cheap or "bare bones" models, of increasing
or decreasing the density of the shoe sole, particularly in the
midsole, in various areas underneath the foot to provide extra
support or special softness where believed necessary. The same
effect is also created by areas either supported or unsupported by
the tread pattern of the bottom sole. The most common example of
this practice is the use of denser midsole material under the
inside portion of the heel, to counteract excessive pronation.
[0066] FIG. 10 illustrates that the applicant's naturally contoured
shoe sole sides can be made to provide a fit so close as to
approximate a custom fit. By molding each mass-produced shoe size
with sides that are bent in somewhat from the position 29 they
would normally be in to conform to that standard size shoe last,
the shoe soles so produced will very gently hold the sides of each
individual foot exactly. Since the shoe sole is designed as
described in connection with FIG. 9 to deform easily and naturally
like that of the bare foot, it will deform easily to provide this
designed-in custom fit. The greater the flexibility of the shoe
sole sides, the greater the range of individual foot size
variations can be custom fit by a standard size. This approach
applies to the fully contoured design described here in FIG. 8A and
in FIG. 15, U.S. patent application Ser. No. 07/239,667 (filed Sep.
2, 1988), as well, which would be even more effective than the
naturally contoured sides design shown in FIG. 10.
[0067] Besides providing a better fit, the intentional undersizing
of the flexible shoe sole sides allows for simplified design of
shoe sole lasts, since they can be designed according to the simple
geometric methodology described in FIG. 27, U.S. patent application
Ser. No. 07/239,667 (filed Sep. 2, 1988). That geometric
approximation of the true actual contour of the human is close
enough to provide a virtual custom fit, when compensated for by the
flexible undersizing from standard shoe lasts described above.
[0068] FIG. 11 illustrates a fully contoured design, but
abbreviated along the sides to only essential structural stability
and propulsion shoe sole elements as shown in FIG. 21 of U.S.
patent application Ser. No. 07/239,667 (filed Sep. 2, 1988)
combined with the freely articulating structural elements
underneath the foot as shown in FIG. 28 of the same patent
application. The unifying concept is that, on both the sides and
underneath the main load-bearing portions of the shoe sole, only
the important structural (i.e. bone) elements of the foot should be
supported by the shoe sole, if the natural flexibility of the foot
is to be paralleled accurately in shoe sole flexibility, so that
the shoe sole does not interfere with the foot's natural motion. In
a sense, the shoe sole should be composed of the same main
structural elements as the foot and they should articulate with
each other just as do the main joints of the foot.
[0069] FIG. 11E shows the horizontal plane bottom view of the right
foot corresponding to the fully contoured design previously
described, but abbreviated along the sides to only essential
structural support and propulsion elements. Shoe sole material
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 the base of
the fifth metatarsal 97 (and the adjoining cuboid in some
individuals). They must be supported both underneath and to the
outside edge of the foot for stability. The essential propulsion
element is the head of the first distal phalange 98. FIG. 11 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.
[0070] The design of the portion of the shoe sole directly
underneath the foot shown in FIG. 11 allows for unobstructed
natural inversion/eversion motion of the calcaneus 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
inversion and eversion) 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 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.
[0071] 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
subdivision are also possible.
[0072] The design in FIG. 11 features an enlarged structural
support at the base of the fifth metatarsal in order to include the
cuboid, which can also come into contact with the ground under arch
compression in some individuals. In addition, the design can
provide general side support in the heel area, as in FIG. 11E or
alternatively can carefully orient the stability sides in the heel
area to the exact positions of the lateral calcaneal tuberosity 108
and the main base of the calcaneus 109, as in FIG. 11E' (showing
heel area only of the right foot). FIGS. 11A-D show frontal plane
cross sections of the left shoe and FIG. 11E shows a bottom view of
the right foot, with flexibility axes 120, 122, 111, 112 and 113
indicated. FIG. 11F shows a sagittal plane cross section showing
the structural elements joined by very thin and relatively soft
upper midsole layer. FIGS. 11G and 11H show similar cross sections
with slightly different designs featuring durable fabric only
(slip-lasted shoe, or a structurally sound arch design,
respectively. FIG. 11I shows a side medial view of the shoe
sole.
[0073] FIG. 11J shows a simple interim or low cost construction for
the articulating shoe sole support element 95 for the heel (showing
the heel area only of the right foot); while it is most critical
and effective for the heel support element 95, it can also be used
with the other elements, such as the base of the fifth metatarsal
97 and the long arch 121. The heel sole element 95 shown can be a
single flexible layer or a lamination of layers. When cut from a
flat sheet or molded in the general pattern shown, the outer edges
can be easily bent to follow the contours of the foot, particularly
the sides. The shape shown allows a flat or slightly contoured heel
element 95 to be attached to a highly contoured shoe upper or very
thin upper sole layer like that shown in FIG. 11F. Thus, a very
simple construction technique can yield a highly sophisticated shoe
sole design. The size of the center section 119 can be small to
conform to a fully or nearly fully contoured design or larger to
conform to a contoured sides design, where there is a large
flattened sole area under the heel. The flexibility is provided by
the removed diagonal sections, the exact proportion of size and
shape can vary.
[0074] FIG. 12 illustrates an expanded explanation of the correct
approach for measuring shoe sole thickness according to the
naturally contoured design, as described previously in FIGS. 23 and
24 of U.S. patent application Ser. No. 07/239,667 (filed Sep. 2,
1988). The tangent described in those figures would be parallel to
the ground when the shoe sole is tilted out sideways, so that
measuring shoe sole thickness along the perpendicular will provide
the least distance between the point on the upper shoe sole surface
closest to the ground and the closest point to it on the lower
surface of the shoe sole (assuming no load deformation).
[0075] FIG. 13 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 so (at least leaving the
midsole bottom surface flat, though the sides can be contoured),
while the bottom or outer sole 126 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. 13A, 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 relatively harder contoured bottom sole
provides good wear for the load-bearing areas.
[0076] FIG. 13B 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.
[0077] FIG. 13C shows in frontal plane cross section the concept
applied to the quadrant sided or single plane design and indicating
in FIG. 13D 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
midsole material to provide for relatively uniform shoe
density.
[0078] FIG. 13E 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 of U.S. patent application Ser. No. 239,667,
filed Sep. 2, 1988; 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 bottom sole.
[0079] FIGS. 14A-14C, 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. 14A, 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 efficiency 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 FIGS. 14B and 14C,
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.
[0080] 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 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 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.
[0081] 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.
[0082] 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.
[0083] FIGS. 15A-15C, 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 the naturally contoured sides 28a design, as shown
in FIGS. 15B and 15C; FIG. 15A 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
previously under FIGS. 14A-14C for the side stability quadrant
embodiment. It is clear from comparing FIGS. 15C and 14C 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 figures.
[0084] 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 scope of the present invention
which is to be defined by the appended claims.
* * * * *