Patent Grant
8863407
The present invention relates to a shoe sole of an athletic shoe suitable for efficient running.
Japanese Laid-Open Patent Publication No. 2008-29717 discloses a structure of a shoe sole that urges the rolling action during walk. The shoe sole disclosed in this document has a narrow groove that is continuous from the rear foot portion to the front foot portion.
[First Patent Document] 2008-29717 (Abstract)
However, this conventional technique aims at increasing walking efficiency of elderly people and infants, and would not increase running efficiency as can be seen from description below.
US2007/0193065A1 and WO2006/120749A1 disclose a resin part formed in a U-letter shape extending from the rear foot portion to the middle foot portion.
However, the resin part disclosed in these documents has a generally equal strength on the medial side and on the lateral side of the foot. No longitudinal groove is formed in the front foot portion of the shoes of these documents.
The shoe sole disclosed in WO2008/047538A1 has a depression in the front foot portion and in the rear foot portion. However, the depression in the front foot portion is not parallel to the outer edge of the front foot portion, but is formed along the medial-lateral center line of the front foot portion.
The shoe sole of this document does not have a flexible band-like area in the medial-lateral central portion of the middle foot portion.
U.S. Pat. No. 6,694,642 discloses a cup sole having a through hole in the central portion of the rear foot portion.
The shoe sole disclosed in Japanese Laid-Open Patent Publication No. 2000-333705 has a depression in the central portion of the rear foot portion, and the medial side of the midsole is harder than the lateral side thereof in the middle foot portion. However, no longitudinal groove is provided in the front foot portion.
Japanese Laid-Open Patent Publication No. 2001-346605 discloses forming a groove in the front foot portion of the outsole.
The documents above do not disclose a structure of a shoe sole that promotes smooth forward movement of the load center from the rear foot portion to the front foot portion of the shoe sole during run to thereby increase the running efficiency.
In a walking or running action where one lands on the heel and takes off at the tiptoe (toe tip), the center of the load on the foot sole moves from the lateral side of the heel through the middle foot portion to the medial side of the tiptoe. By providing a groove on the lower surface of the shoe sole along the trace of movement of the load center, it is expected that the load center is guided along the groove to thereby improve the walking or running efficiency.
As a result of a research by the present inventors, it has been confirmed by computer simulation that the upper surface of the midsole on the opposite side to the lower surface, on which the groove is provided, of the shoe sole sinks more downward than other portions in a cross section of the shoe sole.
On the other hand, Japanese Laid-Open Patent Publication No. 2008-29717 discloses that formation of a groove at a predetermined position along the longitudinal direction of the shoe sole makes it easier for elderly people and infants to walk.
However, as will be described later, the trace of movement of the load center during walk is considerably different from that during run.
That is, the present inventors conducted the following test to obtain the trace of movement during run which is different from that during walk, thereby completing the present invention.
First, a groove 100 shown in
On a track provided with a plate for measuring the center of the load, a subject walked at 8 min/km, and the trace of movement of the load center during walk was measured. The trace of movement 101 is shown in
On the other hand, the same subject ran on the same track at 3.5 min/km, and the trace of movement 101 of the load center during run was measured. The trace of movement 101 is shown in
The following is assumed from this test.
The trace of movement 101 during walk is substantially different from that during run. Particularly, stagnation and variations of the trace of movement 101 are observed during run for the following points in time and points in place.
i) vicinity of the center of the heel upon first strike (instant of landing)
ii) the medial side of the middle foot portion
iii) vicinity of the center of the tiptoe upon takeoff
The stagnation and variations of the trace of movement 101 occur when the load center is not smoothly moving forward. Therefore, by suppressing or preventing the stagnation and variations of the trace of movement 101, the load center smoothly moves forward and efficient running is expected.
The points (i) to (iii) during run will be discussed below in terms of improving the running efficiency.
First discussing the first strike, the landing impact upon the shoe sole at this point is great. Therefore, it is necessary to substantially deform the lateral side of the rear foot portion which first contacts the ground so as to quickly guide the load center to the vicinity of the center of the heel. It is speculated that a large depression is necessary in the vicinity of the center of the heel for this.
Next, the middle foot portion will be discussed.
After the heel lands, as the load center moves to the middle foot portion in front of the heel, the foot leans toward the medial side of the middle foot portion, as shown in
Next, the tiptoe takeoff action will be discussed.
At takeoff, the force acting upon the road surface from the shoe sole is small. Nevertheless, the running efficiency is likely to improve easily if the direction in which one kicks out the tiptoe becomes stable.
The trace of movement 101 at takeoff is unstable during the run of
According to these principles, there is proposed an athletic shoe having a shoe sole of a novel structure.
A shoe sole of an athletic shoe according to one aspect of the present invention is a shoe sole of an athletic shoe suitable for efficient running, wherein: the shoe sole has a front foot portion, a middle foot portion and a rear foot portion continuous with one another in a front-rear direction of a foot, and has a medial side, a lateral side and a central portion between the medial side and the lateral side continuous with one another in a width direction of the foot, the shoe sole comprising: a midsole having an upper surface and a lower surface and absorbing an impact of landing; and an outsole placed below the midsole; the midsole includes a midsole body formed by a foamed resin in the front foot portion; the outsole is provided in the front foot portion and the rear foot portion; the middle foot portion supports an arch of the foot, and a reinforcement member is provided in the middle foot portion for suppressing lowering of the arch; a depression is formed in the rear foot portion which extends forward from a calcaneal bone and which does not contact a ground; a band-like area is provided in the middle foot portion extending in the front-rear direction in the central portion so as to be continuous with the depression; the reinforcement member and the midsole are provided in the middle foot portion so that the upper surface of the midsole less easily sinks downward due to a load from above on the medial side than in the band-like area and on the lateral side; in the front foot portion, a longitudinal groove is formed in the midsole body and the outsole which extends in the front-rear direction in the central portion so as to be continuous with the band-like area; a depth of the longitudinal groove is 5 mm to 20 mm; the longitudinal groove is provided to extend from a rear end of the front foot portion to a proximal interphalangeal joint of a second toe; the longitudinal groove is curved so as to be generally parallel to a lateral edge of the front foot portion of the midsole; a width and the depth of the longitudinal groove are smaller than those of the depression; and the depression, the band-like area and the longitudinal groove are smoothly continuous with one another in the front-rear direction.
Since the upper surface of the midsole lowers in the depression, the band-like area and the groove, the load center smoothly moves forward because of these members.
Particularly, the upper surface of the midsole of the middle foot portion less easily sinks downward on the medial side than in the center and on the lateral side, and it is therefore possible to suppress the movement of the load center to the medial side of the middle foot portion. Therefore, one can expect smooth forward movement of the load center. This, as a result allows for efficient running.
When one takes off at the tiptoe of the front foot portion, the shoe sole bends at the longitudinal groove extending along the lateral edge of the front foot portion. Thus, the shoe sole is easily bent at a predetermined position along tiptoe joints. This makes smooth the action of kicking out diagonally forward toward the lateral side.
Herein, “the depth of the longitudinal groove being 5 mm to 20 mm” means that the average value among deepest portions of the longitudinal groove is 5 mm to 20 mm, and means that the value obtained by integrating the depth of deepest positions along the lateral cross section of the longitudinal groove in the direction in which the longitudinal groove extends, and then dividing the integrated value by the length of the longitudinal groove, is 5 mm to 20 mm.
Therefore, there may locally be some portions over 20 mm or less than 5 mm among the deepest portions of the longitudinal groove.
As the structure of the reinforcement member and the midsole in the middle foot portion, various structures (reinforcement means) as follows may be employed solely or in combination.
As such a structure, a reinforcement member may be employed which has a large rigidity on the medial side and a small rigidity in the band-like area and on the lateral side. For example, in the middle foot portion, the reinforcement member placed on the lower surface of the midsole is thick on the medial side of the lower surface while it is thin, or has a through hole, in the band-like area and on the lateral side of the lower surface.
Still another structure is a structure where the thickness of the midsole body is larger on the medial side and smaller in the band-like area and on the lateral side. In such a case, the midsole body may be divided into upper and lower pieces. One of the separated upper and lower pieces of the midsole body may be provided on the medial side of the middle foot portion while being absent in the band-like area and on the lateral side of the middle foot portion.
Still another structure is a structure where the reinforcement member is bonded on the medial side of the lower surface of the midsole while it is spaced apart from the lower surface of the midsole body and is not bonded to the lower surface in the band-like area. A structure of this type is disclosed in WO2005/037002, disclosure of which is incorporated herein by reference in its entirety.
The reinforcement member may be provided in two, upper and lower, layers only on the medial side, with only one layer provided in the band-like area and on the lateral side.
In the present invention, “the depth of a groove or a depression” means the distance from the ground contact surface (tread surface) to the lower surface of the midsole. On the other hand, whether “the width is small” should be determined by comparing average widths of grooves and depressions.
Where the depth of a groove is less than 5 mm, the load center is unlikely to be localized in the groove portion in the front foot portion. On the other hand, where the depth of a groove is over 20 mm, the front foot portion may become too thick, or one may feel as if the front foot portion were split into medial and lateral pieces, resulting in unstable support of the front foot portion.
Note, however that the depth of a groove may locally be smaller than 5 mm or may locally be deeper than 20 mm.
In view of this, the depth of a groove is preferably 5 mm to 15 mm, and most preferably about 7 mm to about 13 mm.
In the present invention, the width of a depression is preferably about 10 mm to about 60 mm, and more preferably about 12 mm to about 50 mm. Note that the depression may be a groove-like structure elongated in the longitudinal direction.
In a preferred embodiment of the present invention, it further includes: a support member made of a non-foamed resin, having such a shape that it is rolled up along the medial side and the lateral side of the rear foot portion, and supporting the foot in the rear foot portion, wherein: the support member includes a through hole portion for assisting in making it easier for the upper surface of the midsole to sink downward in a central portion of the rear foot portion.
In such a case, the support member makes stable the support of the foot sole while supporting the medial side and the lateral side of the rear foot portion, thereby reliably ensuring that the upper surface of the midsole sinks downward above the depression.
The through hole portion may be formed by a plurality of through holes, as well as by a single large through hole, or may be formed in a grid (mesh) pattern. The through hole portion may be formed by forming the support member in a U-letter shape.
The through hole portion is provided at least in a portion directly below the calcaneal bone, and is preferably provided in an area including the center of the calcaneal bone.
In another preferred embodiment of the present invention, it further includes: a support member extending from the rear foot portion toward the middle foot portion, supporting the medial side of the foot in the middle foot portion, and supporting the lateral side of the foot in the rear foot portion, wherein: the support member forms a part or whole of the reinforcement member in the middle foot portion; and the support member includes a through hole portion for assisting in making it easier for the upper surface of the midsole to sink downward in a central portion of the middle foot portion and the rear foot portion.
In this embodiment, the support member makes stable the support of the foot sole while supporting the medial side and the lateral side of the rear foot portion and the middle foot portion, thereby reliably ensuring that the upper surface of the midsole sinks downward in the depression and the band-like area.
The support member extending from the rear foot portion to be continuous with the middle foot portion will serve to realize smooth forward movement of the load center.
Herein, “to support” means that the support member is placed on the lower surface of the midsole body, and the support member does not have to be bonded to the lower surface.
In this embodiment, more preferably, a bridge piece, forming a part of the reinforcement member, is provided so as to bridge between the rear end of the front foot portion of the midsole body and a front end of the rear foot portion, and the bridge piece serves to make it less easy for the medial side of the middle foot portion to sink downward than the band-like area.
In such a case, the medial side of the middle foot portion is reinforced by the bridge piece, and therefore the upper surface of the midsole more easily sinks downward in the band-like area than on the medial side of the middle foot portion. Thus, the running efficiency is further improved.
In another more preferred embodiment, the midsole further includes the midsole body in the middle foot portion; and the support member is bonded to the lower surface of the midsole body on the medial side of the middle foot portion, and is not bonded to the lower surface of the midsole body and is spaced apart from the lower surface of the midsole body on the lateral side of the middle foot portion.
In such a case, the support member is spaced apart from the lower surface of the midsole body on the lateral side of the midsole body. Therefore, the midsole body easily sinks downward. On the medial side of the middle foot portion where the midsole body is supported by the support member, the upper surface of the midsole less easily sinks downward than on the lateral side of the middle foot portion. Therefore, it is likely that the load center smoothly moves forward in the middle foot portion.
In another more preferred embodiment, the support member further includes a slant portion extending diagonally forward from the lateral side toward the medial side in the band-like area of the middle foot portion; and bending of the middle foot portion in a first direction along a direction in which the slant portion extends requires a larger force than bending of the middle foot portion in a second direction perpendicular to the first direction.
In such a case, the slant portion suppresses bending of the middle foot portion diagonally forward to the medial side. Therefore, it is possible to suppress movement of the load center to the medial side of the middle foot portion.
In such a case, the through hole portion of the support member includes a plurality of through holes parallel to one another extending diagonally forward from the lateral side toward the medial side in the band-like area of the middle foot portion, and a plurality of the slant portions are formed along the through holes.
In another preferred embodiment of the present invention, a first transverse (lateral) groove along a metatarsal phalangeal joint (MP joint) is provided in the front foot portion so as to extend across the outsole; and the first transverse groove divides the outsole in a front-rear direction.
In such a case, the bending of the foot at the MP joint is made smooth, and it is likely that the load center moves along the longitudinal groove.
In such a case, it is more preferred that a second transverse groove extending in a direction across the outsole between a tip of a fifth toe and a tip of a third toe is provided on a lateral side of the front foot portion; and the second transverse groove is formed so as to be more spaced apart from the first transverse groove as it extends toward a lateral edge of the midsole.
The second transverse groove will make smooth the bending of the interphalangeal joint of the tiptoe so that the trace of movement at takeoff is likely to be stable.
In still another preferred embodiment of the present invention, the longitudinal groove is formed so that a width and a depth thereof gradually and smoothly increase from a front end of the longitudinal groove toward the middle foot portion.
In such a case, the load center will likely be guided along the longitudinal groove from the middle foot portion to the front foot portion.
In a preferred embodiment of the present invention, the reinforcement member includes a first member attached to the lower surface of the midsole body on the medial side of the middle foot portion to support the medial side of the foot, and a second member placed below the first member on the medial side of the middle foot portion.
In such a case, it is possible to easily realize a structure where the upper surface of the midsole on the medial side of the middle foot portion less easily lowers, while one is unlikely to feel an upthrust on the medial side of the middle foot portion as the medial side of the middle foot portion is reinforced by two members.
In another preferred embodiment of the present invention, a soft, shock-absorbing element having a smaller Young's modulus than the foamed material is placed on the lateral side of the rear foot portion as a part of the midsole; and a division groove dividing the outsole and the shock-absorbing element along a radial direction extending in a diagonally rearward direction from a center of a heel is provided on the lateral side of the rear foot portion.
In such a case, the soft, shock-absorbing element undergoes substantial compressive deformation upon first strike, and the load center moves toward the center of the heel as it is guided along the division groove which divides the outsole. Therefore, it is possible to suppress stagnation of the load center in the rear foot portion upon first strike. As a result, the running efficiency is improved.
The present invention will be understood more clearly from the following description of preferred embodiments taken in conjunction with the accompanying drawings. Note however that the embodiments and the drawings are merely illustrative, and the scope of the present invention shall be defined by the appended claims. In the accompanying drawings, like reference numerals denote like components throughout the plurality of figures.
An embodiment of the present invention will now be described with reference to
In
The midsole 2 includes an upper surface 2u and a lower surface 2d, and absorbs the impact of landing. The outsole 5 has a bonded surface 50 to be bonded to the lower surface 2d of the midsole 2, and a ground contact surface 51 to be in contact with the road surface.
As shown in
As shown in
The outsole 5 is provided in the front foot portion 1F of
As shown in
As shown in
The heel cup 3 shown in
The heel cup 3 of
As shown in
When landing, the lateral side L of the rear foot portion 1R first contacts the ground, and then the center of the heel contacts the ground. In this process, the division groove 7 promotes an increase in the compressive deformation on the lateral side L of the rear foot portion 1R. Thus, a load center G is smoothly guided from the lateral side L of the rear foot portion 1R toward a position lateral to the central portion 1Rm, as shown in
As shown by the dotted area of
Upon landing, the upper surface 2u (
Note that as can be seen from
As shown by the dotted area of
The structure will now be described in detail.
In the middle foot portion 1M shown in
In the central portion C of the middle foot portion 1M shown in
As shown in
As shown in
In
The flexural rigidity (bending stiffness) of the bridge piece 4 shown in
The bridge piece 4 suppresses the upthrust on the foot sole. The structure of the bridge piece 4 also prevents the bending of the shoe sole on the medial side M of the middle foot portion 1M, and suppresses the pronation of the foot. This suppresses the movement of the load center G to the medial side M in the middle foot portion 1M.
In
With the structure of the slant portions 33, bending of the middle foot portion 1M in the first direction D1 along the direction in which the slant portions 33 extend requires a larger force than bending of the middle foot portion 1M in the second direction D2 perpendicular to the first direction D1. This suppresses the movement of the load center G of
As shown by the dotted area of
In the treading action during run, the longitudinal groove 10 of
In
Therefore, in the treading action during run, the load center G of
The depth D of the longitudinal groove 10 of
As shown in
In
The outsole 5 is divided in the front-rear direction by the first transverse groove 11 and the second transverse groove 12. The second transverse groove 12 is formed so as to be more spaced apart from the first transverse groove 11 of
As shown by the dotted area in
A portion (tip portion) of the longitudinal groove 10, the second transverse groove 12 and the extension groove 13 partition the tiptoe portion 1T and the tread portion of the shoe sole from each other by the grooves. Therefore, when the foot takes off, the shoe sole easily bends along the grooves 10, 12 and 13. As a result, the load center G of
In
Next, a test in which athletic shoes of the present embodiment were worn by the subject will be described.
The subject ran on the track at 3.5 min/km, and the trace of movement 101 of the load center G during run was measured. The trace of movement 101 is shown in
As can be seen from
While preferred embodiments have been described above with reference to the drawings, various obvious changes and modifications will readily occur to those skilled in the art upon reading the present specification.
For example, it is not necessary to provide the slant portions 33. It is not necessary to provide the first and second through holes 31 and 32. The slant portions 33 may be formed by ribs extending in the first direction D1, without forming the second through holes 32.
In the middle foot portion 1M, the rigidity of the lateral side L may be greater than that of the band-like area 9. Without providing the second through hole 32, the heel cup 3 or the reinforcement member may be formed to be thinner in the portion of the band-like area 9, or the heel cup 3 and the reinforcement member may be provided so that they are not bonded to the lower surface of the midsole 2 in the portion of the band-like area 9.
It is not necessary to provide a gel in a portion of the midsole 2. For example, a pod-like part or a foamed resin may be provided instead of the gel.
It is not necessary to provide the heel cup 3. A portion of the reinforcement member may be formed by a foamed material.
It is not necessary to provide the division groove 7, the first transverse groove 11, the second transverse groove 12 and the extension groove 13.
Thus, such changes and modifications are deemed to fall within the scope of the present invention, which is defined by the appended claims.
The present invention is applicable to athletic shoes that are worn in daily lives, sports and competitions.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/067710 | 9/30/2008 | WO | 00 | 4/22/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/038266 | 4/8/2010 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6694642 | Turner | Feb 2004 | B2 |
| 7290357 | McDonald et al. | Nov 2007 | B2 |
| 7941941 | Hazenberg et al. | May 2011 | B2 |
| 8166672 | Murphy et al. | May 2012 | B2 |
| 20070193065 | Nishiwaki et al. | Aug 2007 | A1 |
| 20090013556 | Nishiwaki et al. | Jan 2009 | A1 |
| 20100005684 | Nishiwaki et al. | Jan 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 2431857 | May 2007 | GB |
| 10-108704 | Apr 1998 | JP |
| 2000-333705 | Dec 2000 | JP |
| 2001-346605 | Dec 2001 | JP |
| 2002-034605 | Feb 2002 | JP |
| 2008-029717 | Feb 2008 | JP |
| 2006120749 | Nov 2006 | WO |
| 2008047538 | Apr 2008 | WO |
| Entry |
|---|
| International Search Report for corresponding International Application No. PCT/JP2008/067710 mailed Dec. 22, 2008. |
| Reply to Written Opinion for corresponding International Application No. PCT/JP2008/067710 (English translation) mailed Apr. 24, 2009. |
| Number | Date | Country | |
|---|---|---|---|
| 20110185590 A1 | Aug 2011 | US |
