Note: Descriptions are shown in the official language in which they were submitted.
1 TWO DENSITY IN~LINED SOLE RU_NING SHOE
This invention relates generally to athletic
foot wear and more particularly to running shoes.
~arious athletic shoes particularly suited for
running are commercially available. Such shoes commonly
include what can be called a "neutral plane" sole, that is
a sole which is of uniform thickness between the inner
(varus) side of the shoe and the outer (valgus) side of -the
.shoe. Such soles are also commonly ormed of unlform
density between the varus and valgus s:idcs. The human
anatomy is such that when a person runs~ or walks ~or khat
matter, the rcar val~us portion oE l;he hcel o:~ cach ~oot
makes initial contact during each step. The ground con-
tacting foot then rolls inward, a process called pronation,
whereupon the person's body weight is brought from the
outside edge of the foot inward toward the center of the
arch. The foot then rolls outwardly and toes off toward
the great toe to complete a step.
It is widely recognized that the vast majorlty oE
runners e~hlbit improper pronation when running ln prlor
art shoes llke those described above. Io that end, many
people initially land on the outside of the heel of the
ground contacting foot, with the foot rolling inward with
improper biomechanical action and remainlng rolled inward.
Such improper action is referred to as overpronation. In
addition, it has been shown that when running, three to
four ti~es the gravitational Eorce is applied to the outside
edge of the foot, and in particular to the heel area, than
occurs when walking. The high force concentrated at the
heel area, coupled with the tendency of most rwnners to roll
their feet inward forcefully during running results in
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1 increased shock to the foot and increased heel wear o-~ the
shoe being worn.
In United States Patent No. 4,180,92~ ~Subotnick)
issued January 1, 1980, assigned to the same assignee as
this invention, there is disclosed and claimed a running
shoe featuring a sole having a wedged portion can~ed upward
in a transverse direction from the outer side of the shoe
to the inner side of the shoe so that during running a
substantial portion of the sole makes contact with the
ground during each step. ~lthough this type o~ construct:ion
remedies many of thc drawbacks ~associat~cl witll a COnV~
tionally cleslgned rullnillg sho~, thc physi.c.L:I canting o~E
the sole may not be desired by some runners, e.g., slow
runners.
In United States Patent No. 4,364,188 (Turner et
al.) issued ~ecember 21, 1982, assigned to the same assignee
as this invention, there is disclosed and clalmed a running
shoe
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1 having a neutral plane sole including portions a-t the heel on ~he
varus side which are of higher density (durometer) than the
remaining portion of the sole in the interest o~ "rearfoot
st.ability".
It is a general object of the instant invention to
provide running shoes which overcome the disadvantages inherent in
the prior art running shoes.
It is a further object of the instant invention to
provide running shoes which distribute impac-t shock evenly during
runn.ing, yet at the same -time employing a transversely level or
"neutral plane" sole.
It is a further object o:E the instant :inv~ntion to pro-
vide a pai.r o-f neutral plane runnincJ shoes, each Oe which prov.icle
mean!; Eor lessening the abnormal proncltion o~ the oot as th~ arcl
flattens during running.
I. is still a further object oE -the instan-t invention to
pro~,ide a pair of running shoes, each of which having a neutral
plane sole construction, which permits greater contact surface
area t.han conventional shoes, thereby distr.ibuting impac-t shock
more evenly during running, yet providi.ng medialongitudinal arch
support for decreasing abnormal pronation, while ~I.lowing :Eor the
natural proration of the foot.
. These and other ob~ec-ts of the instant invention are
achieved by providing a pair of running shoes. Each of the shoes
comprises an upper and a sole. The sole has an inner side and an
outer side, with the width oE said sole being defi~ed there-
between. The sole runs the length of ~he shoe from the heel to
the toe and comprises an outsole and a midsole. The midsole
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1 includes a first member and a second member, each member being a
var.iable thickness across the ~idth thereo-E. The first member is
disposed above saia second member so tha-t the combined -thickness
of said members is constant across the wid~h of said sole. Each
o~ the members is formed of a material having a different
durome~er, so that the ratio of the thicXness of th~ higher
durometer material relative to the lower durome-ter material is
greatest i~nediately adjacent the inner side of the sole and is
lowest ir~nediately adjacent the outer side.
Other objects and many of the attendant advantages of the
instant invention wi:Ll become readily apparent by re~rence to the
accompanying draw.inss whereirl:
Fig. 1 is a p~rspect.ive view of the runn.ing ~loe of the
inst2nt invention;
Fig. 2 is an enlarged sectional view taken along line 2-2
o Fig. l; and
Fig. 3 is an enlarged sect.ional view taken along line 3-3
of ~ig. l.
Referring now to the various figures of the draw:ing
wherein like reference charclcters reEer to like parts, -there .is
shown at 20 in Fig. 1 a running shoe constructed in accordance
with the instan-t invention. Shoe 20 is designed to be used by the
competi-tive runner or recrea-tional jogger alike.
Each shoe basically comprises conventional upper 22 and a
sole unit 24. The upper 22 has an inner or varus side 26 and an
ou-ter or valgus side 28. The sole unit 24 runs the entire length
of -the shoe ~rom the heel 30 to the toe 32 be-tween the varus and
valgus si.des 26 and 28, respectively.
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1 In referring to Fig. 2 it can be seen that sole unit 24
comprises an outsole 34 and a midsole 36, The outsole is of
conventional construc-tion and includes plural gripping elements or
cleats 38.
The midsole is formed as a composite struc-ture and, as
will be discribed in detail hereinaftter, is arranged to provide
the over-pronation lessening characteristics exhibited by running
shoes constructed in accordance with the teachings of the afore
men,loned United States Patent No. 4,180,924 in a neutral plane
sole. To that end the midsole 36 includes two layers, namely top
layer 40 and bottom layer ~2. 'rhe layers extend for ~ s~lbstantial
length o the sole betweell the heel ancl to a point ad~acent the
front or the arch. Eac'h 1a~er :i6 Eormed o~ A resi:L:ient materia'l
li.Xe that used in midsoles of conventional running shoes, except
tha, -the hardness or durome-ter of each layer is different from the
other.
In the embodirnent of the midsole shown in Fig. 2 the
upper layer is of higher durometer material than the lower layer.
For exam~le, depending upon the type of shoe, the upper layer can
have a durometer within the ran~e o ~5~ 10~, Shore ~,'while t'he
lower Layer has a durometer within the range oE 35-~ 10~, Shore ~.
The midsole layers 36 are preferably made of ethyl vinyl acetate
(EVA) but alternatively, may be made of polyurethane or any number
of other ma~erials used in running shoes.
The thickness oE each layer varies across the width oE
the sole, i.e., between the varus and valgus sides, but with the
combined -thickness oE both layers being cons-tant across said
width. This feature ensures that the sole is of the "neu-tral
plane" type.~
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1 The ]ayers 40 and 42 are cons-tructed so -that the layer
having the thicker portion contiguous wi-th the varus side is of
the higher durometer ma-terial. Accordingly -the hardness of the
midsole contiguous with -the Var~l5 side oE the sole is hiyher than
that of the valgus side. With such a construction, during the
pronation phase of each running step the varus side of the shoe
does no-t compress as readily as the valgus side. Therefore, the
abnornal tendency toward over pronation is obvia-ted or at least
minimized.
In the embodimen-t of Fig. 2, the top layer 40, which is
forme~ of higher densiiy material tapers linearly in thicXness
Erom .~e varus side to the valgus side, with the ratio of the
higher clensity materlal to the lower density material being
ap~ro~imately 3 to 1 adjacent the varus side and approxima-tely 1
to 3 a_jacent ~he ~algus side. Conversely the lower layer 42,
whicn is formed OL the lower density material, tapers linearly in
thi_kness from the valgus side to the varus side. The degree o-E
taper of both laye}s is the same. The layers are adhesively
secured along .heir interface 44. The top surface 46 of the -top
layer 40 and the bottom surface 48 of the bottom layer are
disposed hori~ontally so that the combined overall -thickness of
two layers of the midsole 36 in a transverse direction across the
width of the sole is constan-t.
An alternative embodiment of the midsole o-f the instant:
invention is shown in Fig. 3 wherein the higher density and lower
density materials, forming the two layers of -the midsole are
transposed. i~ccordingly in this embodiment -the top layer 40 is
formed of the lower density material and tapers from the valgus
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1 side -to varus side, while tlle bottom layer 42 is formed of the
higher density material and tapers from the varus side to the
valgus side.
As is conventional, the midsole 36 is thicker under the
heel of the upper and tapers downward longit:udinal under the arch
toward the forefoot area, to provide the necessary heel lift or
elevation for comfortable, safe running. The total thickness of
midsole 36 is between 1.5 cm and 2.5 cm at its -thickest ~or-tion,
with the exact thickness varying depending on several factors,
such as the type of running intended (e.g., racing, recreational
jogging, etc.) and the personal preference of the wearer.
It must be pointecl out at this juncture that the two
layers 40 and 4~ need not taper linearly, ~s sllown .in Fi~s. 2 ~ncl
3, ~or neecl they be of correspollc1ing thickn~sse~ tap~r:i.n~ in
opp~site directions, 50 loncl as the ratio Oe the tllickness oE th~
high~r durometer material relative to the lower durometer ma-terial
is .~ eatPst adjac~nt the varus side, e,g., the layer of higher
density has its thic~er sicle at the varus side of the sole, and
the top surface of the top layer is substantially horizontal in
the -transverse direction when -the outsole is flat on a horizontal
running surface. Moreover, the two layers need not be formed as
separate units which are secured toge-ther.
Without Eurther elaboration, the foregoi.ng will so fully
illustrate my invention that others may, by applying current or
future knowledge, readily adop-t the same for use under various
conditions of service.
