U.S. patent application number 09/785200 was filed with the patent office on 2002-01-03 for shoes sole structures.
This patent application is currently assigned to Anatomic Research, Inc.. Invention is credited to Ellis, Frampton E. III.
Application Number | 20020000051 09/785200 |
Document ID | / |
Family ID | 27494690 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000051 |
Kind Code |
A1 |
Ellis, Frampton E. III |
January 3, 2002 |
Shoes sole structures
Abstract
A shoe sole particularly for athletic footwear for supporting
the foot of an intended wearer having multiple rounded bulges
existing as viewed in a frontal plane of the sole during a shoe
unloaded, upright condition. The bulges include concavely rounded
inner and outer portions for approximating the structure of and
support provided by the natural foot. When utilizing multiple
bulges, the shoe sole may include indentations between the bulges
to define a flexibility axis of the shoe sole. The bulges can be
located proximate to important structural support areas of an
intended wearer's foot on either or both sides of the shoe sole or
the middle portion of the shoe sole, or on various combinations of
these locations. The bulges include side and upper midsole portions
to improve stability while also improving cushioning and comfort.
The bulges can be tapered as viewed in a horizontal plane to
improve flexibility and reduce unnecessary weight.
Inventors: |
Ellis, Frampton E. III;
(Arlington, VA) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
Anatomic Research, Inc.
|
Family ID: |
27494690 |
Appl. No.: |
09/785200 |
Filed: |
February 20, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09785200 |
Feb 20, 2001 |
|
|
|
09734905 |
Dec 13, 2000 |
|
|
|
09734905 |
Dec 13, 2000 |
|
|
|
08477954 |
Jun 7, 1995 |
|
|
|
6163982 |
|
|
|
|
08477954 |
Jun 7, 1995 |
|
|
|
08376661 |
Jan 23, 1995 |
|
|
|
08376661 |
Jan 23, 1995 |
|
|
|
08127487 |
Sep 28, 1993 |
|
|
|
08127487 |
Sep 28, 1993 |
|
|
|
07729886 |
Jul 11, 1991 |
|
|
|
07729886 |
Jul 11, 1991 |
|
|
|
07400714 |
Aug 30, 1989 |
|
|
|
Current U.S.
Class: |
36/25R ;
36/88 |
Current CPC
Class: |
A43B 13/18 20130101;
A43B 13/148 20130101; A43B 13/143 20130101; A43B 13/146 20130101;
A43B 13/145 20130101; A43B 13/20 20130101 |
Class at
Publication: |
36/25.00R ;
36/88 |
International
Class: |
A43B 013/00 |
Claims
What is claimed is:
1. A shoe sole for a shoe and other footwear, particularly athletic
shoes and including street shoes, comprising: an upper, foot
sole-contacting surface of the shoe sole that is shaped to conform
to the shape of at least part of a sole of a heel of a wearer's
foot, including at least part of an underneath sole portion and at
least one side portion of the foot sole; the shoe sole is
characterized by said at least one conforming shoe sole side
portion having a thickness and density which varies from a uniform
thickness and density by not less than 5 percent nor more than 25
percent, when measured in transverse plane cross sections; the shoe
sole thickness varies when measured in sagittal plane cross
sections and is greater in a heel area than in a forefoot area; the
thickness and density of the shoe sole, which varies from a uniform
thickness and density by not less than 5 percent nor more than 25
percent as measured in transverse plane cross sections, extends
from the underneath sole portion through the conforming side
portion at the heel at least through a sideways tilt angle of 20
degrees.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 08/477,954, filed Jun. 7, 1995, now U.S. Pat.
No. ______, which is a continuation-in-part of U.S. patent
application Ser. No. 08/376,661, filed Jan. 23, 1995, which is a
continuation of U.S. patent application Ser. No. 08/127,487 filed
Sep. 28, 1993, now abandoned, which is a continuation of U.S.
patent application Ser. No. 07/729,886 filed Jul. 11, 1991, now
abandoned, which is a continuation of U.S. patent application Ser.
No. 07/400,714 filed Aug. 30, 1989, now abandoned.
FIELD AND BACKGROUND OF THE INVENTION
[0002] This invention relates generally to the structure of soles
of shoes and other footwear, including soles of street shoes,
hiking boots, sandals, slippers, and moccasins. More specifically,
this invention relates to the structure of athletic shoe soles,
including such examples as basketball and running shoes.
[0003] Still more particularly, this invention relates to
variations in the structure of such soles using a theoretically
ideal stability plane as a basic concept.
[0004] The applicant has introduced into the art the concept of a
theoretically ideal stability plane as a structural basis for shoe
sole designs. The theoretically ideal stability plane was defined
by the applicant in previous copending applications as the plane of
the surface of the bottom of the shoe sole, wherein the shoe sole
conforms to the natural shape of the wearer's foot sole,
particularly its sides, and has a constant thickness in frontal or
transverse plane cross sections. Therefore, by definition, the
theoretically ideal stability plane is the surface plane of the
bottom of the shoe sole that parallels the surface of the wearer's
foot sole in transverse or frontal plane cross sections.
[0005] The theoretically ideal stability plane concept as
implemented into shoes such as street shoes and athletic shoes is
presented in U.S. Pat. Nos. 4,989,349, issued Feb. 5, 1991 and
5,317,819, issued Jun. 7, 1994, both of which are incorporated by
reference, as well as U.S. Pat. No. 5,544,429 issued Aug. 13, 1996;
U.S. Pat. No. 4,989,349 issued from U.S. patent application Ser.
No. 07/219,387. U.S. Pat. No. 5,317,819 issued from U.S. patent
application Ser. No. 07/239,667.
[0006] This new invention is a modification of the inventions
disclosed and claimed in the earlier applications and develops the
application of the concept of the theoretically ideal stability
plane to other shoe structures. Each of the applicant's
applications is built directly on its predecessors and therefore
all possible combinations of inventions or their component elements
with other inventions or elements in prior and subsequent
applications have always been specifically intended by the
applicant. Generally, however, the applicant's applications are
generic at such a fundamental level that it is not possible as a
practical matter to describe every embodiment combination that
offers substantial improvement over the existing art, as the length
of this description of only some combinations will testify.
[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] The purpose of this application is to specifically describe
some of the most important combinations, especially those that
constitute optimal ones.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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
[0014] In its simplest conceptual form, the applicant's invention
is the structure of a conventional shoe sole that has been modified
by having its sides bent up so that their inner surface conforms to
a shape nearly identical (instead of the shoe sole sides being flat
on the ground, as is conventional). This concept is like that
described in FIG. 3 of the applicant's U.S. Pat. No. 5,317,819
("the '819 patent"); for the applicant's fully contoured design
described in FIG. 15 of the '819 patent, the entire shoe
sole--including both the sides and the portion directly underneath
the foot--is bent up to conform to a shape nearly identical but
slightly smaller than the contoured shape of the unloaded foot sole
of the wearer, rather than the partially flattened load-bearing
foot sole shown in FIG. 3.
[0015] This theoretical or conceptual bending up must be
accomplished in practical manufacturing without any of the
puckering distortion or deformation that would necessarily occur if
such a conventional shoe sole were actually bent up simultaneously
along all of its the sides; consequently, manufacturing techniques
that do not require any bending up of shoe sole material, such as
injection molding manufacturing of the shoe sole, would be required
for optimal results and therefore is preferable.
[0016] It is critical to the novelty of this fundamental concept
that all layers of the shoe sole are bent up around the foot sole.
A small number of both street and athletic shoe soles that are
commercially available are naturally contoured to a limited extent
in that only their bottom soles, which are about one quarter to one
third of the total thickness of the entire shoe sole, are wrapped
up around portions of the wearers' foot soles; the remaining soles
layers, including the insole, midsole and heel lift (or heel) of
such shoe soles, constituting over half of the thickness of the
entire shoe sole, remains flat, conforming to the ground rather
than the wearers' feet. (At the other extreme, some shoes in the
existing art have flat midsoles and bottom soles, but have insoles
that conform to the wearer's foot sole.)
[0017] Consequently, in existing contoured shoe soles, the total
shoe sole thickness of the contoured side portions, including every
layer or portion, is much less than the total thickness of the sole
portion directly underneath the foot, whereas in the applicant's
shoe sole inventions the shoe sole thickness of the contoured side
portions are at least similar to the thickness of the sole portion
directly underneath the foot.
[0018] This major and conspicuous structural difference between the
applicant's underlying concept and the existing shoe sole art is
paralleled by a similarly dramatic functional difference between
the two: the aforementioned equivalent or similar thickness of the
applicant's shoe sole invention maintains intact the firm lateral
stability of the wearer's foot, that stability as demonstrated when
the foot is unshod and tilted out laterally in inversion to the
extreme limit of the normal range of motion of the ankle joint of
the foot. The sides of the applicant's shoe sole invention extend
sufficiently far up the sides of the wearer's foot sole to maintain
the lateral stability of the wearer's foot when bare.
[0019] In addition, the applicant's shoe sole invention maintains
the natural stability and natural, uninterrupted motion of the
wearer's foot when bare throughout its normal range of sideways
pronation and supination motion occurring during all load-bearing
phases of locomotion of the wearer, including when the wearer is
standing, walking, jogging and running, even when the foot is
tilted to the extreme limit of that normal range, in contrast to
unstable and inflexible conventional shoe soles, including the
partially contoured existing art described above. The sides of the
applicant's shoe sole invention extend sufficiently far up the
sides of the wearer's foot sole to maintain the natural stability
and uninterrupted motion of the wearer's foot when bare. The exact
thickness and material density of the shoe sole sides and their
specific contour will be determined empirically for individuals and
groups using standard biomechanical techniques of gait analysis to
determine those combinations that best provide the barefoot
stability described above.
[0020] In general, the applicant's preferred shoe sole embodiments
include the structural and material flexibility to deform in
parallel to the natural deformation of the wearer's foot sole as if
it were bare and unaffected by any of the abnormal foot
biomechanics created by rigid conventional shoe sole.
[0021] 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.
[0022] In another aspect of the invention, 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.
[0023] The shoe sole of the invention 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.
[0024] These and other features of the invention will become
apparent from the detailed description of the invention which
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIGS. 1A to 1I illustrate functionally the principles of
natural deformation.
[0026] FIG. 2 shows variations in the relative density of the shoe
sole including the shoe insole to maximize an ability of the sole
to deform naturally.
[0027] FIG. 3 is a rear view of a heel of a foot for explaining the
use of a stationery sprain simulation test.
[0028] FIG. 4 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.
[0029] FIGS. 5A and 5B are diagrams of the forces on a foot when
rotating in a shoe of the type shown in FIG. 2.
[0030] FIG. 6 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.
[0031] FIG. 7 is a force diagram during rotation of a shoe having
motion control devices and heel counters.
[0032] FIG. 8 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.
[0033] FIG. 9 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.
[0034] FIGS. 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, and 10J
show 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.
[0035] FIG. 11 is a diagram serving as a basis for an expanded
discussion of a correct approach for measuring shoe sole
thickness.
[0036] FIG. 12 shows an embodiment wherein the bottom sole includes
most or all of the special contours of the new designs and retains
a flat upper surface.
[0037] FIG. 13 shows, in frontal plane cross section at the heel
portion of a shoe, a shoe sole with naturally contoured sides based
on a theoretically ideal stability plane.
[0038] FIG. 14 shows a fully contoured shoe sole that follows the
natural contour of the bottom of the foot as well as its sides,
also based on the theoretically ideal stability plane.
[0039] FIGS. 15A-C, as seen in FIGS. 15A to 15C in frontal plane
cross section at the heel, show a quadrant-sided shoe sole, based
on a theoretically ideal stability plane.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] FIGS. 1A-C illustrate, in frontal plane cross sections in
the heel area, the applicant's concept of the theoretically ideal
stability plane applied to shoe soles.
[0041] FIGS. 1A-1C 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.
[0042] FIG. 1A 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. 1B and flatten just as the human foot bottom
is slightly round 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. 1A would deform by flattening to look
essentially like FIG. 1B.
[0043] FIGS. 1A and 1B 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.
[0044] For the case shown in FIG. 1B, 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.
[0045] FIG. 1B 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 flatten in deformation in
the shoe sole. FIG. 1C 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 fully
supported structurally and its natural stability is maintained
undiminished, regardless of shoe tilt. In marked contrast, a
conventional shoe, shown in FIG. 3, makes contact with the ground
with only its relatively sharp edge when tilted and is therefore
inherently unstable.
[0046] 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.
[0047] FIG. 1C also represents with reasonable accuracy a shoe sole
design corresponding to FIG. 1B, a naturally contoured shoe sole
with a conventional built-in flattening deformation, except that
design would have a slight crimp at 145. Seen in this light, the
naturally contoured side design in FIG. 1B is a more conventional,
conservative design that is a special case of the more generally
fully contoured design in FIG. 1A, which is the closest to the
natural form of the foot, but the least conventional.
[0048] In its simplest conceptual form, the applicant's FIG. 1
invention is the structure of a conventional shoe sole that has
been modified by having its sides bent up so that their inner
surface conforms to the shape of the outer surface of the foot sole
of the wearer (instead of the shoe sole sides being flat on the
ground, as is conventional); this concept is like that described in
FIG. 3 of the applicant's '819 patent. For the applicant's fully
contoured design, the entire shoe sole--including both the sides
and the portion directly underneath the foot--is bent up to conform
to the shape of the unloaded foot sole of the wearer, rather than
the partially flattened load-bearing foot sole shown in FIG. 3 of
the '819 patent.
[0049] This theoretical or conceptual bending up must be
accomplished in practical manufacturing without any of the
puckering distortion or deformation that would necessarily occur if
such a conventional shoe sole were actually bent up simultaneously
along all of its the sides; consequently, manufacturing techniques
that do not require any bending up of shoe sole material, such as
injection molding manufacturing of the shoe sole, would be required
for optimal results and therefore is preferable.
[0050] It is critical to the novelty of this fundamental concept
that all layers of the shoe sole are bent up around the foot sole.
A small number of both street and athletic shoe soles that are
commercially available are naturally contoured to a limited extent
in that only their bottom soles, which are about one quarter to one
third of the total thickness of the entire shoe sole, are wrapped
up around portions of the wearer's foot soles; the remaining sole
layers, including the insole, the midsole and the heel lift (or
heel) of such shoe soles, constituting over half of the thickness
of the entire shoe sole, remains flat, conforming to the ground
rather than the wearers' feet.
[0051] Consequently, in existing contoured shoe soles, the shoe
sole thickness of the contoured side portions is much less than 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. This approach applies to
the fully contoured design described here in FIG. 1A and in FIG. 15
of the '819 patent.
[0052] As discussed earlier by the applicant, the critical
functional feature of a shoe sole is that it deforms under a
weight-bearing load to conform to the foot sole just as the foot
sole deforms to conform to the ground under a weight-bearing load.
So, even though the foot sole and the shoe sole may start in
different locations--the shoe sole sides can even be conventionally
flat on the ground--the critical functional feature of both is that
they both conform under load to parallel the shape of the ground,
which conventional shoes do not, except when exactly upright.
Consequently, the applicant's shoe sole invention, stated most
broadly, includes any shoe sole--whether conforming to the wearer's
foot sole or to the ground or some intermediate position, including
a shape much smaller than the wearer's foot sole--that deforms to
conform to the theoretically ideal stability plane, which by
definition itself deforms in parallel with the deformation of the
wearer's foot sole under weight-bearing load.
[0053] Of course, it is optimal in terms of preserving natural foot
biomechanics, which is the primary goal of the applicant, for the
shoe sole to conform to the foot sole when on the foot, not just
when under a weight-bearing load. And, in any case, all of the
essential structural support and propulsion elements must be
supported by the foot sole.
[0054] To the extent the shoe sole sides are easily flexible, as
has already been specified as desirable, the position of the shoe
sole sides before the wearer puts on the shoe is less important,
since the sides will easily conform to the shape of the wearer's
foot when the shoe is put on that foot. In view of that, even shoe
sole sides that conform to a shape more than slightly smaller than
the shape of the outer surface of the wearer's foot sole would
function in accordance with the applicant's general invention,
since the flexible sides could bend out easily a considerable
relative distance and still conform to the wearer's foot sole when
on the wearer's foot.
[0055] FIG. 3 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. 3.
Lateral (inversion) sprains are the most common ankle sprains,
accounting for about three-fourths of all.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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. 3. 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.
[0061] 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.
[0062] 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.
[0063] FIG. 4 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. 4.
[0064] 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. 4 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.
[0065] 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.
[0066] FIG. 5A 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.
[0067] 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.
[0068] 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-reinforcing cycle. The more the shoe tilts, the more
destabilizing torque is produced to further increase the tilt.
[0069] The problem may be easier to understand by looking at the
diagram of the force components of body weight shown in FIG.
5A.
[0070] 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.
[0071] FIG. 5B 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.
[0072] FIG. 6 show a summary of the force components at shoe sole
tilts of 0, 45 and 90 degrees. FIG. 6, which uses the same
reference numerals as in FIG. 5, 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.
[0073] 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.
[0074] 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. 6. In the untilted position, there is no
destabilizing unsupported force component 136.
[0075] FIG. 7 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. 7
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.
[0076] FIG. 8 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 desirable 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. 8 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.
[0077] FIG. 9 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. 9 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.
[0078] FIG. 10 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 the '819
patent combined with the freely articulating structural elements
underneath the foot as shown in FIG. 28 of the '819 patent. 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.
[0079] FIG. 10E shows the horizontal plane bottom view of the right
foot corresponding to the fully contoured design previously
described, but abbreviated, that is, having indentations along the
sides to only essential structural support and propulsion elements
which are all concavely rounded bulges as shown. The concavity of
the bulges exists with respect to an intended wearer's foot
location in the shoe. 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. 10 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.
[0080] The design of the portion of the shoe sole directly
underneath the foot shown in FIG. 10 allows for unobstructed
natural inversion/eversion motion of the calcaneus by providing
maximum shoe sole flexibility particularly at a midtarsal portion
of the sole member, 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.
[0081] 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.
[0082] The design in FIG. 10 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. 10E 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. 10E (showing
heel area only of the right foot). FIGS. 10A-D show frontal plane
cross sections of the left shoe and FIG. 10E shows a bottom view of
the right foot, with flexibility axes 120, 122, 111, 112 and 113
indicated. FIG. 10F shows a sagittal plane cross section showing
the structural elements joined by very thin and relatively soft
upper midsole layer 147. FIGS. 10G and 10H show similar cross
sections with slightly different designs featuring durable fabric
only (slip-lasted shoe), or a structurally sound arch design,
respectively. FIG. 10I shows a side medial view of the shoe
sole.
[0083] FIG. 10J 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. 10F. 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.
[0084] FIG. 11 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 the '819 patent. 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).
[0085] FIG. 12 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 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. 12A, 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.
[0086] FIGS. 13-15 show frontal plane cross sectional views of a
shoe sole according to the applicant's prior inventions based on
the theoretically ideal stability plane, taken at about the ankle
joint to show the heel section of the shoe. The concept of the
theoretically ideal stability plane, as developed in the prior
applications as noted, defines the plane 51 in terms of a locus of
points determined by the thickness(es) of the sole.
[0087] FIG. 13 shows, in a rear cross sectional view, the inner
surface of the shoe sole conforming to the natural contour of the
foot and the thickness of the shoe sole remaining constant in the
frontal plane, so that the outer surface coincides with the
theoretically ideal stability plane.
[0088] FIG. 14 shows a fully contoured shoe sole design that
follows the natural contour of all of the foot, the bottom as well
as the sides, while retaining a constant shoe sole thickness in the
frontal plane.
[0089] The fully contoured shoe sole assumes that the resulting
slightly rounded bottom when unloaded will deform under load and
flatten just as the human foot bottom is slightly rounded unloaded
but flattens under load; therefore, shoe sole material must be of
such composition as to allow the natural deformation following that
of the foot. The design applies particularly to the heel, but to
the rest of the shoe sole as well. By providing the closest match
to the natural shape of the foot, the fully contoured design allows
the foot to function as naturally as possible. Under load, FIG. 2
would deform by flattening to look essentially like FIG. 13. Seen
in this light, the naturally contoured side design in FIG. 13 is a
more conventional, conservative design that is a special case of
the more general fully contoured design in FIG. 14, which is the
closest to the natural form of the foot, but the least
conventional. The amount of deformation flattening used in the FIG.
13 design, which obviously varies under different loads, is not an
essential element of the applicant's invention.
[0090] FIGS. 13 and 14 both show in frontal plane cross sections
the theoretically ideal stability plane, which is also
theoretically ideal for efficient natural motion of all kinds,
including running, jogging or walking. FIG. 14 shows the most
general case, 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(es) in a frontal plane cross section,
and, second, by the natural shape of the individual's foot surface
29.
[0091] For the special case shown in FIG. 13, 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(es); second, by the natural
shape of the individual's foot; and, third, by the frontal plane
cross section width of the individual's load-bearing footprint 30b,
which is defined as the upper surface of the shoe sole that is in
physical contact with and supports the human foot sole.
[0092] The theoretically ideal stability plane for the special case
is composed conceptually of two parts. Shown in FIG. 13, the first
part is a line segment 31b of equal length and parallel to line 30b
at a constant distance(s) equal to shoe sole thickness. This
corresponds to a conventional shoe sole directly underneath the
human foot, and also corresponds to the flattened portion of the
bottom of the load-bearing foot sole 28b. 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(es) from the closest point on the
contoured side inner edge 30a.
[0093] In summary, the theoretically ideal stability plane is used
to determine a geometrically precise bottom contour of the shoe
sole based on a top contour that conforms to the contour of the
foot.
[0094] 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. The theoretical ideal
was taken to be that which is closest to natural.
[0095] FIG. 15 illustrates in frontal plane cross section another
variation that uses stabilizing quadrants 26 at the outer edge of a
conventional shoe sole 28b illustrated generally at the reference
numeral 28. The stabilizing quadrants would be abbreviated in
actual embodiments.
* * * * *