U.S. patent application number 10/361103 was filed with the patent office on 2004-08-12 for footwear with dual-density midsole and deceleration zones.
This patent application is currently assigned to Columbia Sportswear North America, Inc.. Invention is credited to Laska, Daniel S..
Application Number | 20040154188 10/361103 |
Document ID | / |
Family ID | 32824136 |
Filed Date | 2004-08-12 |
United States Patent
Application |
20040154188 |
Kind Code |
A1 |
Laska, Daniel S. |
August 12, 2004 |
Footwear with dual-density midsole and deceleration zones
Abstract
An athletic shoe midsole includes a hard elastic stabilizing
member that extends generally around a central opening through
which a relatively soft elastic cushioning layer extends downwardly
from a heel center beneath a wearer's calcaneus bone to thereby
form a heel-cushioning pillar. The stabilizing member extends along
lateral and medial sides of the pillar to prevent pronation and
supination, and preferably includes a protrusion that extends into
a depression in the heel-cushioning pillar in alignment with a line
of flexure of the heel region to thereby affect flexure
characteristics of a heel region of the shoe. The midsole may also
include flex grooves, channels, and/or notches aligned with the
line of flexure for promoting the desired flexure characteristics
in the heel region of the sole and for helping decelerate the
wearer's heel-toe gait during the stance phase of the wearer's gait
cycle.
Inventors: |
Laska, Daniel S.; (Portland,
OR) |
Correspondence
Address: |
STOEL RIVES LLP
900 SW FIFTH AVENUE
SUITE 2600
PORTLAND
OR
97204
US
|
Assignee: |
Columbia Sportswear North America,
Inc.
Portland
OR
|
Family ID: |
32824136 |
Appl. No.: |
10/361103 |
Filed: |
February 7, 2003 |
Current U.S.
Class: |
36/25R ;
36/31 |
Current CPC
Class: |
A43B 7/24 20130101; A43B
13/026 20130101; A43B 13/186 20130101; A43B 5/06 20130101; A43B
13/12 20130101 |
Class at
Publication: |
036/025.00R ;
036/031 |
International
Class: |
A43B 013/00; A43B
013/14 |
Claims
1. In an athletic shoe having a shoe upper and a sole, the sole
including a heel region having lateral and medial side margins, and
the sole including an outsole and a midsole interposed between the
outsole and the shoe upper, an improved sole, comprising: a soft
elastic cushioning layer extending under the shoe upper, the
cushioning layer including a heel-cushioning pillar positioned
under a heel center of the shoe upper corresponding to a wearer's
calcaneus bone, the pillar including lateral, medial, and aft
sides, and further including a depression in one of the sides of
the pillar; and a hard elastic stabilizing member for preventing
pronation and supination, the stabilizing member having a hardness
greater than the cushioning layer and extending from the medial
side of the pillar and around the aft side and at least part of the
lateral side of the pillar, the stabilizing member including a
protrusion extending into the depression of the pillar, the
protrusion and the depression positioned in alignment with a line
of flexure of the heel region that extends diagonally from a point
on the medial side margin of the sole aft of the heel center toward
the lateral side margin of the sole forward of the heel center,
thereby affecting flexure characteristics of the heel region and
enhancing a medial support characteristic of the sole.
2. The athletic shoe sole of claim 1 in which the protrusion of the
stabilizing member is sized to mate with the depression in the
pillar for securely adhering thereto.
3. The athletic shoe sole of claim 1 in which: the pillar extends
downwardly from the wearer's foot to terminate at a bottom end; and
the pillar is tapered along its sides so that it is narrowest at
its bottom end.
4. The athletic shoe sole of claim 1 in which the cushioning layer
and the stabilizing member include a flex groove that extends
across the sole in alignment with the line of flexure.
5. The athletic shoe sole of claim 1 in which the outsole includes
an aft crash pad portion, a main heel portion positioned forward of
the crash pad portion, and a thin section that extends diagonally
across the heel region in alignment with the line of flexure to
connect the crash pad portion to the main heel portion, the thin
section facilitating manufacture of the athletic shoe and
complementing the flexure characteristics of the midsole.
6. The athletic shoe sole of claim 5 in which the outsole includes
a notch positioned under at least a portion of the protrusion of
the stabilizing member and the depression of the pillar, the notch
interposed between the crash pad portion and the main heel portion
of the outsole.
7. The athletic shoe sole of claim 5 in which the thin section of
the outsole includes an outsole flex channel in alignment with the
line of flexure to promote flexing in the heel region along the
line of flexure.
8. The athletic shoe sole of claim 7 in which the cushioning layer
and the stabilizing member include respective first and second
midsole flex channels corresponding to the outsole flex
channel.
9. The athletic shoe sole of claim 1 in which the sole further
comprises a shank stiffener positioned beneath the arch of the
wearer's foot.
10. The athletic shoe sole of claim 9 in which the shank stiffener
is bonded to the stabilizing member.
11. The athletic shoe sole of claim 1 in which the stabilizing
member includes an upper joint surface, the cushioning layer
includes a lower joint surface abutting the upper joint surface of
the stabilizing member, and the upper and lower joint surfaces
include interlocking wave surfaces extending along at least part of
the lateral and medial sides of the sole.
12. The athletic shoe sole of claim 1 in which the cushioning layer
is formed of an ethylvinylacetate (EVA) material having a hardness
between approximately 50 and approximately 54 Asker C.
13. The athletic shoe sole of claim 1 in which the stabilizing
member is formed of an ethylvinylacetate (EVA) material having a
hardness between approximately 54 and approximately 58 Asker C.
14. In an athletic shoe having a shoe upper and a sole, the sole
including a heel region having lateral and medial sides, an
improved sole comprising: a soft elastic cushioning layer extending
under the shoe upper; and a hard elastic stabilizing member
positioned beneath at least a portion of the cushioning layer for
preventing pronation and supination, the stabilizing member having
a hardness greater than the cushioning layer and extending
generally around a central opening through which the cushioning
layer extends downwardly from a heel center of the wearer beneath a
calcaneus bone of the wearer, the stabilizing member including a
protrusion extending into the opening in alignment with a line of
flexure of the heel region that extends diagonally from a point on
the medial side of the sole aft of the heel center toward the
lateral side of the sole forward of the heel center, thereby
affecting flexure characteristics of the heel region.
15. The athletic shoe sole of claim 14 in which: the central
opening in the stabilizing member extends in a generally vertical
direction so that the central opening includes a top portion
nearest the wearer's foot and a bottom portion opposite the top
portion; and the central opening tapers so that it is narrower at
its bottom portion than at its top portion.
16. The athletic shoe sole of claim 14 in which: the central
opening in the stabilizing member extends in a generally vertical
direction so that the central opening includes a top portion
nearest the wearer's foot and a bottom portion opposite the top
portion; and the cushioning layer tapers where it extends through
the central opening so that the cushioning layer is narrower at the
bottom portion of the central opening than at the top portion of
the central opening.
17. The athletic shoe sole of claim 14, further comprising a flex
groove extending across the cushioning layer and the stabilizing
member in alignment with the line of flexure.
18. The athletic shoe sole of claim 14, further comprising an
outsole positioned under the cushioning layer and the stabilizing
member, the outsole including an aft crash pad portion, a main heel
portion positioned forward of the crash pad portion, and a thin
section that extends diagonally across the heel region in alignment
with the line of flexure to connect the crash pad portion to the
main heel portion, the thin section facilitating manufacture of the
athletic shoe and complementing the flexure characteristics of the
sole.
19. The athletic shoe sole of claim 18 in which the outsole
includes a notch positioned under at least a portion of the
protrusion of the stabilizing member, the notch interposed between
the crash pad portion and the main heel portion of the outsole.
20. The athletic shoe sole of claim 18 in which the thin section of
the outsole includes an outsole flex channel in alignment with the
line of flexure to promote flexing in the heel region along the
line of flexure.
21. The athletic shoe sole of claim 20 in which the cushioning
layer and the stabilizing member include respective first and
second midsole flex channels corresponding to the outsole flex
channel.
22. The athletic shoe sole of claim 14 in which the sole further
comprises a shank stiffener positioned beneath the arch of the
wearer's foot.
23. The athletic shoe sole of claim 22 in which the shank stiffener
is bonded to the stabilizing member.
24. The athletic shoe sole of claim 14 in which the stabilizing
member includes an upper joint surface, the cushioning layer
includes a lower joint surface abutting the upper joint surface of
the stabilizing member, and the upper and lower joint surfaces
include interlocking wave surfaces extending along at least part of
the lateral and medial sides of the sole.
25. The athletic shoe sole of claim 14 in which the cushioning
layer is formed of an ethylvinylacetate (EVA) material having a
hardness between approximately 50 and approximately 54 Asker C.
26. The athletic shoe sole of claim 14 in which the stabilizing
member is formed of an ethylvinylacetate (EVA) material having a
hardness between approximately 54 and approximately 58 Asker C.
Description
RELATED APPLICATIONS
[0001] This application is related to a U.S. design patent
application titled "Athletic Shoe Sole," filed concurrently
(Attorney Docket No. 50053/3:2).
TECHNICAL FIELD
[0002] The present invention relates to soles for footwear and, in
particular, to an improved dual-density midsole including
deceleration features desirable for increased stability and injury
prevention during jogging and running.
BACKGROUND OF THE INVENTION
[0003] The soles of athletic shoes commonly include a soft
cushioning layer and a so-called medial post. The medial post is
located along the medial side of the sole's heel region and is made
firmer and more resilient than the cushioning layer in order to
prevent an undesirable inward pivoting of the foot called
"pronation" (also known as "overpronation").
[0004] U.S. Pat. No. 4,614,046 of Dassler describes a multilayer
midsole for an athletic shoe that includes a softly elastic inner
layer and a hard spring-elastic polyurethane stabilizer extending
under a heel portion of the inner layer in the shape of a
horizontal C. The stabilizer is oriented to leave a vacant space
centered under the wearer's heel and an opening along the lateral
side of the midsole, which are filled by a cushioning piece of
softly elastic plastic material such as polyurethane. The '046
patent describes how this configuration helps prevent pronation
while also preventing the heel bone from "stepping through" the
cushioning piece, which can otherwise cause heel bruises.
[0005] U.S. Pat. No. 4,766,679 of Bender attempts to improve on the
midsole of the '046 patent by providing a stabilizing member
including a U-shaped part that extends around the entire heel edge
and a bar part that closes the U-shaped part at the middle of the
foot to create a window into which an island of the full thickness
of the midsole engages. The stated purpose of the midsole of Bender
is to prevent supination (undesirable outward pivoting of the foot)
while also preventing pronation and heel bruising.
[0006] While known heel stabilizing elements address issues of heel
cushioning, pronation, and supination, they may also tend to
increase the overall stiffness of the sole in the heel region.
Excess stiffness in the heel region of the sole can cause an
undesirable rate of pronation, which can result in undesirable
distribution of weight during the stance phase of a wearer's gait
cycle, i.e., from heel strike, to mid-stance, to toe off, leaving
the wearer susceptible to injury. Thus the inventors have
recognized a need for an improved sole that not only prevents
supination, pronation, and heel impact injuries, but that also
includes features for improved flexibility in the heel region to
decelerate a wearer's heel-toe gait during the stance phase of the
wearer's gait cycle.
SUMMARY OF THE INVENTION
[0007] In accordance with the present invention, an athletic shoe
sole includes a midsole comprising a soft elastic cushioning layer
extending under a shoe upper and a relatively hard elastic
stabilizing member positioned beneath at least a portion of the
cushioning layer for preventing pronation and supination. The
stabilizing member extends generally around a central opening
through which the cushioning layer extends downwardly from a heel
center beneath a wearer's calcaneus bone to thereby form a
heel-cushioning pillar. The pillar is preferably tapered to provide
gradually increasing cushioning resistance as heel impact forces
increase.
[0008] In one embodiment, the stabilizing member includes a
protrusion that extends into a depression in the heel-cushioning
pillar to affect flexure characteristics of the heel region. The
protrusion and the depression are preferably aligned with a line of
flexure of the heel region that extends diagonally from a point on
the medial side of the sole aft of the heel center toward the
lateral side of the sole forward of the heel center.
[0009] To help achieve desired flexure characteristics, the
stabilizing member is preferably C-shaped to include a gap along a
lateral side margin of the heel region of the sole, which gap is
filled by a portion of the soft cushioning layer. In other
embodiments, one or more of the cushioning layer, the stabilizing
member, and an outsole of the sole may include flex grooves,
channels, and/or notches aligned with the line of flexure for
promoting the desired flexure characteristics in the heel region of
the sole and, in particular, for helping decelerate the wearer's
heel-toe gait during the stance phase of the wearer's gait
cycle.
[0010] To further facilitate the desired flexure characteristics
and to simplify manufacturing, the outsole may include along the
line of flexure a concave thin section that nests in and
complements a corresponding flex groove of the midsole. The thin
section connects an aft crash pad portion of the outsole to a
forward main heel portion of the outsole, which serves to reduce
the number of parts that must be handled and assembled during the
manufacturing process, potentially reducing waste and manufacturing
costs.
[0011] Additional aspects and advantages will be apparent from the
following detailed description of preferred embodiments, which
proceeds with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a lateral side pictorial view of an athletic shoe
in accordance with a preferred embodiment;
[0013] FIG. 2 is a lateral side elevation of a sole of the athletic
shoe of FIG. 1, with surface contours omitted for clarity;
[0014] FIG. 3 is a bottom view of the sole of FIG. 2 showing detail
of an outsole of the sole;
[0015] FIG. 4 is an enlarged top view of the sole of FIGS. 2 and 3,
including a superimposed illustration of the skeletal structure of
a wearer's foot;
[0016] FIG. 5 is a cross section view taken along line 5-5 of FIG.
4;
[0017] FIG. 6 is a cross section view taken along line 6-6 of FIG.
4;
[0018] FIG. 7 is a cross section view taken along line 7-7 of FIG.
4;
[0019] FIG. 8 is an exploded assembly view of the sole of FIGS. 2-7
taken from an upper vantage point on the lateral side of the
sole;
[0020] FIG. 9 is an exploded assembly view of the sole of FIGS. 2-8
taken from a lower vantage point on the medial side of the
sole;
[0021] FIG. 10 is a schematic cross section view of the sole of
FIGS. 2-9 taken along line 10-10 of FIG. 4, including detail of a
calcaneus bone and fleshy pad of a wearer's foot in a resting
position; and
[0022] FIG. 11 is a view of the schematic cross section of FIG. 10
that illustrates how a stabilizing member of the sole controls the
position and movement of the fleshy pad of the foot during impact,
to utilize the foot's natural cushioning mechanism.
[0023] In the figures, like reference numerals refer to the same or
similar parts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] FIG. 1 is a lateral side pictorial view of an athletic shoe
10 in accordance with a preferred embodiment. FIGS. 2 and 3 are
respective lateral side elevation and bottom plan views of a sole
14 of shoe 10 of FIG. 1. Surface contours 16 of sole 14 shown in
FIG. 1 are omitted in FIG. 2 to simplify the drawing. With
reference to FIGS. 1-3, shoe 10 includes a shoe upper 20 attached
to sole 14 in a conventional manner, such as by molding or
stitching. Sole 14 includes a midsole 24 interposed between shoe
upper 20 and an outsole 26 of sole 14. For athletic shoes intended
for running and trail running, midsole 24 is preferably made of a
soft elastic material such as foamed polyurethane or
ethylvinylacetate (EVA). With reference to FIGS. 1 and 2, midsole
24 preferably includes at least two components made of different
densities of elastic material. A soft elastic cushioning layer 30
extends under shoe upper 20 and serves as the primary cushioning
component of sole 14. Cushioning layer 30 is preferably formed of
EVA material having a hardness in the range of approximately 50 to
approximately 54 Asker C durometer scale. A relatively hard elastic
stabilizing member 34 is positioned under a heel region 36 of
cushioning layer 30 and is preferably formed of an EVA material
having a hardness in the range of approximately 54 to approximately
58 Asker C. Outsole 26 may be formed of a wear-resistant elastic
material such as rubber. Cushioning layer 30, stabilizing member
34, and outsole 26 are bonded together with adhesive or by molding,
comolding, or thermal fusing.
[0025] FIG. 4 is an enlarged top view of sole 14, including a
superimposed illustration of the skeletal structure of a wearer's
foot 40 shown in broken lines. A perimeter of a foot bed 42 of shoe
10 is also illustrated in broken lines in FIG. 4, for reference
only and without limiting the scope of the invention. FIGS. 5, 6,
and 7 are cross section views of sole 14 taken along respective
lines 5-5, 6-6, and 7-7 of FIG. 4. FIGS. 8 and 9 are exploded
assembly views of sole 14 shown from respective upper and lower
vantages. FIG. 8 shows a lateral side margin 46 of sole 14, and
FIG. 9 shows a medial side margin 48 of sole 14. In FIG. 9, shoe
upper 20 is also illustrated. With reference to FIGS. 4-9,
stabilizing member 34 extends generally around a central opening 50
(FIGS. 8 and 9) through which cushioning layer 30 extends
downwardly beneath a heel center 52 corresponding to a calcaneus
bone 54 of foot 40 (FIG. 4) to form a heel-cushioning pillar 58.
Stabilizing member 34 preferably includes a C-shaped portion 62
extending along respective forward, medial, and aft sides 66, 68,
and 70 of opening 50 and pillar 58. C-shaped portion 62 of
stabilizing member 34 preferably also extends from aft side 70
along at least part of a lateral side 72 of opening 50 and pillar
58. Advantageously, the relatively hard and more dense stabilizing
member 34 and, in particular, C-shaped portion 62 may prevent both
pronation and supination of a wearer's foot 40 by providing support
along both lateral and medial side margins 46 and 48 in heel region
36. Preferably, stabilizing member 34 does not form a closed loop
around opening 50, but is instead C-shaped to include a gap 76
along lateral side margin 46 in heel region 36. Gap 76 is filled by
a lateral tab portion 82 of the relatively soft cushioning layer 30
for increased flexibility in heel region 36. Preferably, gap 76 is
large enough to facilitate flexure in heel region 36 but small
enough so that stabilizing member 34 extends along a substantial
portion of lateral side margin 46 of sole 14 to prevent supination.
For example, gap 76 may have a width in the range of approximately
10 mm to approximately 30 mm. In the preferred embodiment, gap 76
is positioned generally in alignment with forward side 66 of
opening 50 so that a leading edge 86 of gap 76 is contiguous with
forward side 66 of opening 50. However, gap 76 may, in alternative
embodiments (not shown), be positioned at any location along
lateral side margin 46. In still other embodiments (not shown), gap
76 is omitted altogether, so that stabilizing member 34 forms a
closed loop or ring around opening 50.
[0026] Pillar 58 extends downwardly from the wearer's foot 40 to
terminate at a bottom end 92. Sides 66, 68, 70, and 72 of pillar 58
are tapered so that pillar 58 is narrowest at bottom end 92.
Corresponding sides 66, 68, 70, and 72 of opening 50 are also
tapered from a top portion of opening 50 to a bottom portion of
opening 50, so that opening 50 is narrower at the bottom portion
than at the top portion. The tapered shape of opening 50 and pillar
58 provides gradually increasing cushioning resistance as heel
impact forces increase. FIG. 10 is a schematic cross section view
of sole 14 taken along line 10-10 of FIG. 4, including detail of
calcaneus bone 54 and a fleshy pad 96 of foot 40 when in a resting
position. FIG. 11 is a view of foot 40 and sole 14 that illustrates
how stabilizing member 34 directs the forces of impact and controls
the position and movement of fleshy pad 96 during heel impact. FIG.
11 illustrates how the tapered sides of pillar 58 provide cup-like
support beneath foot 40 to direct fleshy pad 96 centrally under
heel center 52 (FIG. 4) and calcaneus bone 54, thereby creating a
"sweet spot" that improves the natural cushioning capabilities of
foot 40 and fleshy pad 96. As impact forces "F" increase, tapering
of pillar 58 and stabilizing member 34 provides gradually
increasing cushioning resistance to prevent the wearer's heel from
"stepping through" pillar 58, thereby avoiding bruising of
calcaneus bone 54. Heel strike energy is funneled during
deceleration then redirected to the acceleration phase of the
heel-toe gait, by storing the energy of impact and releasing it
gradually during mid-stance and toe off.
[0027] Revisiting FIGS. 4, 6, 8, and 9, stabilizing member 34
includes a protrusion 102 that extends into a corresponding
depression 104 in pillar 58. Protrusion 102 and depression 104 are
preferably closely mated and securely adhered together. Protrusion
102 and depression 104 are also preferably aligned with a line of
flexure 110 that represents a bending axis for heel region 36. Line
of flexure 110 extends diagonally from a point on medial side
margin 48 of sole 14 aft of heel center 52 toward lateral side
margin 46 of sole 14 forward of heel center 52. Line of flexure 110
may be a straight line, as shown in FIG. 4, or a curved line, as
shown in FIG. 3. Skilled persons will understand that line of
flexure 110 need not have a fixed position relative to sole 14 and
represents an approximate bending axis for heel region 36 of sole
14. Positioning of protrusion 102 and depression 104 along line of
flexure 110 affects a flexure characteristic of sole 14 and
increases a medial support characteristic of sole 14. The size and
shape of protrusion 102 also allows outsole 26 to overlap and
protect the seam between protrusion 102 and pillar 58, which can
help prevent delamination of stabilizing member 34 and cushioning
layer 30 at the seam.
[0028] Preferably, stabilizing member 34 includes an upper joint
surface 124 extending along at least a portion of lateral and
medial side margins 46 and 48 of sole 14. A corresponding lower
joint surface 132 of cushioning layer 30 abuts and interlocks with
upper joint surface 124 along interlocking wave joints 138 that
extend along at least part of lateral and medial side margins 46
and 48, respectively, as best shown in FIGS. 2, 8, and 9.
Interlocking wave joints 138 help prevent cushioning layer 30 from
slipping horizontally relative to stabilizing member 34 and outsole
26 upon heel impact and during a deceleration phase of the wearer's
gait cycle.
[0029] To help achieve desired flexure characteristics, one or more
of cushioning layer 30, stabilizing member 34, and outsole 26 may
include one or more flex grooves, channels, notches, or other
structures, typically aligned with line of flexure 110, which
promote flexibility in heel region 36. The flexibility-enhancing
structures counteract the stiffening effect of stabilizing member
34, thereby promoting deceleration of a wearer's heel-toe gait
during the stance phase of the wearer's gait cycle. Controlled
deceleration reduces the shock of impact on the wearer's foot,
ankle, knee, and hip joints.
[0030] With reference to FIG. 3, in a preferred embodiment, sole 14
includes a flex groove 150 preferably extending across sole 14 in
alignment with line of flexure 110. With reference to FIGS. 3 and
9, flex groove 150 includes a first midsole flex channel 154
extending diagonally across bottom end 92 of pillar 58 and a second
midsole flex channel 158 extending along a bottom side 160 of
stabilizing member 34 in alignment with first midsole flex channel
154. Flex groove 150 and first and second midsole flex channels 154
and 158 preferably have a width in the range of approximately 3 mm
to approximately 5 mm, for example, but could be larger or smaller
in alternative embodiments. First and second notches 172 and 174
are provided in outsole 26 along respective lateral and medial side
margins 46 and 48. First and second notches 172 and 174 increase
the flexibility of outsole 26 along line of flexure 110 and
accommodate respective first and second midsole flex channels 154
and 158 (or portions thereof), which may extend through first and
second notches 172 and 174 to thereby also promote flexibility and
to serve as ground-contacting elements of sole 14. Second notch 174
is preferably positioned beneath at least a portion of protrusion
102 and depression 104 and more preferably ends at a location
outwardly of a seam where protrusion 102 contacts pillar 58, so
that the seam is hidden by outsole 26 and protected from damage.
Outsole 26 preferably includes an aft crash pad portion 182 and a
forward main heel portion 184 that are connected by a thin section
190 extending generally along line of flexure 110 between first and
second notches 172 and 174. Thin section 190 may be adhered to a
portion of first midsole flex channel 154 (overlapping the seam
between protrusion 102 and pillar 58) and may be formed or molded
in a concave shape to thereby form an outsole flex channel that
promotes flexibility along line of flexure 110. Thin section 190
and first and second notches 172 and 174, reduce the weight of sole
14 and help the heel region of outsole 26 to perform as a hinge for
improved deceleration effect. Thin section 190 also serves to
reduce the number of parts that must be handled and assembled
during manufacture of sole 14 and shoe 10, which can reduce waste
and manufacturing cost.
[0031] Sole 14 may include additional flexibility-enhancing
structures such as anterior flex grooves 192 and 193 (FIGS. 3, 5,
and 9) in anterior sections 194 of respective cushioning layer 30
and outsole 26, for example. The position and size of flex grooves
150, 192, and 193 and flex channels 154 and 158 are selected based
on an activity for which the shoe 10 is designed, such as
basketball, running, or trail running, for example.
[0032] Sole 14 preferably includes a shank stiffener 196 positioned
forward of flex groove 150 and line of flexure 110. Shank stiffener
196 may be made of a hard plastic resin and adhered to stabilizing
member 34, cushioning layer 30, or outsole 26. Shank stiffener 196
provides stiffness in the shank region of shoe 10 and prevents
injury when stepping on hard objects such as rocks and tree roots,
for example, as will be readily understood by those of skill in the
art.
[0033] It will be obvious to those having skill in the art that
many changes may be made to the details of the above-described
embodiments without departing from the underlying principles of the
invention. Furthermore, the described features, structures, or
characteristics may be combined in any suitable manner in one or
more embodiments. Those skilled in the art will recognize that the
invention can be practiced without one or more of the specific
details, or with other methods, components, materials, etc. In some
instances, well-known structures, materials, or operations are not
shown or not described in detail above, to avoid obscuring aspects
of the embodiments. The scope of the present invention should,
therefore, be determined only by the following claims.
* * * * *