shoes

Abstract

To provide a shoe that achieves both foot stability and flexibility of the ankle joint during walking and knee flexion / extension movements while supporting weight loads with both feet. [Solution] The lifting shoe 1 comprises a sole 10 and an upper 20. The sole 10 has a sole area division line DL set at a position closer to the heel than the MP joint α, dividing the entire sole area SA into a forefoot area FA and a rearfoot area BA. The sole 10 has an outsole 11 and a midsole 12. The outsole 11 has an outsole forefoot portion 110 in the forefoot area FA which includes the area corresponding to the MP joint α. The outsole forefoot portion 110 is set to have an enlarged sole portion 115 which expands the sole area outward from the outer circumference of the reference sole shape SS, when the outer circumference foot shape drawn along the outer shape of the wearer's foot F is defined as the reference sole shape SS.

Description

Technical Field

[0001] The present disclosure relates to shoes.

Background Art

[0002] Conventional lifting shoes are known as a type of shoes that use a high-hardness rubber material for the outsole material to maximize the force pressing the floor and the floor reaction force for lifting heavy weights, and to prevent wobbling caused by the foot twisting (rotating) inside the shoe, as well as insert a carbon plate in the toe portion of the outsole, and narrow the sole and upper by squeezing them toward the toe (hereinafter referred to as "Conventional Example 1").

[0003] In lifting methods such as snatch, clean and jerk performed in weightlifting competitions and training, an action is performed in which the user jumps while trying to lift a heavy weight, spreads both legs left and right or up and down, and lands. In response to this, conventional lifting shoes use a TPU material for the heel material to withstand the landing impact. Further, conventional lifting shoes are configured to secure a foot accommodation space by the sole and upper at the toe portion, and a type of shoe using a soft material as the midsole of the forefoot portion is disclosed in Patent Document 1, so as to facilitate bending of foot joints such as the forefoot corresponding to the landing motion (hereinafter referred to as "Conventional Example 2").

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] By the way, the squat, a lifting technique used in powerlifting competitions and training, involves lifting a (very) heavy barbell from a rack onto the back and shoulders (holding it behind the back), taking a few steps backward, bending the knees deeply at the backed position, and then straightening the bent knees to stand up. This entire sequence is performed within a set time while leaning the upper body forward. Therefore, powerlifters who compete in powerlifting competitions or those who perform squats in training do not jump when lifting heavy weights, unlike those who perform other lifting techniques such as snatches, cleans, or jerks. For this reason, those who perform squats want to wear lifting shoes that achieve both foot stability and ankle flexion flexibility, rather than shoes that can withstand landing impact or landing motion. Here, "ensuring foot stability" means minimizing foot wobble within the shoe so that both feet supporting the weight load do not wobble during walking, including the back step, and during knee flexion and extension movements. Furthermore, "ensuring flexibility in ankle flexion" means ensuring the mobility of the forefoot, that is, the ease of bending the foot from the MP joint, so that the center of gravity is optimized during walking, including backstepping, and the force pushing against the floor and the ground reaction force are maximized during knee flexion and extension movements.

[0006] In contrast, the conventional lifting shoe in Example 1 uses a high-hardness rubber material for the outsole and incorporates a carbon plate in the toe area of ​​the outsole, thus ensuring foot stability by suppressing wobbling inside the shoe. However, the structure of the conventional shoe in Example 1 compresses the toes to prevent the foot from wobbling inside the shoe, which causes the transverse arch that spreads laterally at the MP joint to collapse. As a result, the conventional lifting shoe in Example 1 has the problem that, during walking and knee flexion and extension movements while supporting weight loads with both feet, the foot does not bend from the MP joint position, resulting in a lack of flexibility in the ankle joint.

[0007] Furthermore, the lifting shoes in Conventional Example 2 ensure flexibility in the ankle joint. However, because the shoe structure of Conventional Example 2 uses a soft material in the midsole of the forefoot, the forefoot sinks into the shoe in a twisted state to a certain extent in the width direction of the foot, that is, towards the inside or outside of the foot. As a result, the lifting shoes in Conventional Example 2 have the problem of the foot wobbling inside the shoe and lacking foot stability during walking and knee flexion and extension movements while supporting a weight load with both feet.

[0008] This disclosure addresses the above-mentioned issues and aims to provide a shoe that achieves both foot stability and flexibility of the ankle joint during walking and knee flexion / extension movements while supporting weight loads with both feet. [Means for solving the problem]

[0009] The shoes of this disclosure include a sole and an upper fixed to the sole and covering the upper part of the wearer's foot. The sole has a sole area division line set at a position closer to the heel than the MP joint, which flexes at the position between the metatarsal bones and phalanges at the base of the toes, and the sole area division line divides the entire sole into a toe-side forefoot area and a heel-side hindfoot area. The sole has an outsole having a contact surface with the floor or ground and a midsole fixed on the outsole. The outsole has an outsole forefoot portion in the forefoot area which includes the area corresponding to the MP joint. The outsole forefoot portion has a sole shape that has an enlarged sole portion, which expands the sole area outward from the outer circumference of the reference sole shape, when the outer circumference foot shape drawn along the outer shape of the wearer's foot is used as the reference sole shape. [Effects of the Invention]

[0010] The shoes disclosed herein can achieve both foot stability and flexibility of the ankle joint during walking and knee flexion / extension movements while supporting weight loads with both feet. [Brief explanation of the drawing]

[0011] [Figure 1] This is an external perspective view showing a pair of lifting shoes according to Embodiment 1. [Figure 2] This is a plan view showing the sole surface of a lifting shoe. [Figure 3] This is a bottom view diagram showing the sole of a lifting shoe. [Figure 4] This is a side view showing the side of the sole of a lifting shoe. [Figure 5] This figure shows the planar structure of the sole cover sewn to the upper and the cross-sectional structure of the sole as shown by line AA in Figure 2. [Figure 6] Figure 2 shows the sole back structure according to line BB (a), the sole cross-sectional structure according to line CC (b), and the sole cross-sectional structure according to line DD (c). [Figure 7] This is an explanatory diagram showing the skeletal structure of the foot with MP joints. [Figure 8] This is a plan view showing the forefoot portion of the outsole. [Figure 9] Figure 8 is a cross-sectional view showing the cross-sectional structure of the forefoot of the outsole along the EE line. [Figure 10] This is an explanatory diagram showing the movements of plantar flexion and dorsiflexion of the foot. [Figure 11] This is a diagram illustrating the squat competition method. [Figure 12] This is an arch diagram illustrating the transverse arch, outer longitudinal arch, and inner longitudinal arch. [Figure 13] This is an explanatory diagram of the foot bending action at the toe side in the comparative example shoe. [Figure 14] This is a perspective view from the front, looking diagonally upward, showing the toe break position in the lifting shoe of Embodiment 1. [Figure 15] This is an explanatory diagram of the foot bending action from the toe break position in the lifting shoes of Embodiment 1. [Modes for carrying out the invention]

[0012] The shoe of the present disclosure will be described with reference to the accompanying drawings illustrating the lifting shoe (an example of the shoe) of Embodiment 1 for implementing the present disclosure. In the accompanying drawings, the longitudinal axis aligned with the length direction of the foot is defined as the X-axis, and the lateral axis perpendicular to the X-axis and aligned with the width direction of the foot is defined as the Y-axis. In the accompanying drawings, the shoe center line is designated as CL0, the toe center line as CL1, and the heel center line as CL2. The shoe center line CL0 is a line connecting the first toe position P0 and the heel position P2. The toe center line CL1 is a line drawn from the second toe position P1, which is medial to the first toe position P0, to divide the forefoot part. The heel center line CL2 is a line drawn from the heel position P2 to divide the rearfoot part. In the description of Embodiment 1, FIG. 1 targets the lifting shoes for both left and right feet, and FIGS. 2 to 15 target the lifting shoe for the right foot for the description. (Embodiment 1)

[0013] [Overall Configuration of Lifting Shoe (FIGS. 1 to 7)] As shown in FIGS. 1 to 6, the lifting shoe 1 includes a sole 10, an upper 20 fixed to the sole 10 and covering the upper part of the wearer's foot excluding the sole 10, and a sole cover 30.

[0014] As shown in FIG. 7, the skeleton of the foot F includes, as tarsal bones, a calcaneus B1, a talus B2, a navicular bone B3, a cuboid bone B4, and three cuneiform bones B5, B6, B7. The skeleton of the foot F includes five metatarsal bones B8, B9, B10, B11, B12 as metatarsal bones. The skeleton of the foot F includes, as phalanges, five proximal phalanges B13, B14, B15, B16, B17, four middle phalanges B18, B19, B20, B21, and five distal phalanges B22, B23, B24, B25, B26. The MP joint α refers to the joint connecting the five metatarsal bones B8, B9, B10, B11, B12 and the five proximal phalanges B13, B14, B15, B16, B17.

[0015] As shown in Figure 2, the sole 10 has a sole area division line DL set at a position closer to the heel than the MP joint α, which flexes at the position between the metatarsal bones and phalanges at the base of the toes. As shown in Figure 2, the sole 10 divides the entire sole area SA into a forefoot area FA on the toe side and a rearfoot area BA on the heel side by the sole area division line DL set in the Y-axis direction. The sole area division line DL is set, for example, at a position about 40% from the front tip of the outsole when the total length in the X-axis direction is 100%, and at a position where the MP joint α is included in the forefoot area FA. The sole 10 has an outsole 11 having a contact surface 111 with the floor surface G, and a midsole 12 fixed on top of the outsole 11. The sole 10 has both the outsole 11 and the midsole 12 in the rearfoot area BA, and only the outsole 11 in the forefoot area FA.

[0016] The outsole 11 is a sole component used in the part that contacts the floor surface G, and is present in the entire sole area SA, which is the combination of the forefoot area FA and the rearfoot area BA. The outsole 11 is made of a hard rubber material called high-hardness rubber. The outsole 11 has a contact surface 111, an outsole bonding surface 112, an outsole surface 113, and an outsole peripheral wall portion 114. The outsole 11 has an inner shape that wraps around the toe portion of the foot F in the forefoot area FA, with space in between.

[0017] As shown in Figure 3, the contact surface 111 is a fully flat surface with an anti-slip structure against the floor surface G, making the entire surface planar. The sole shape of the contact surface 111 is the same as the enlarged sole shape of the outsole 11, which will be described later. Therefore, the contact area of ​​the contact surface 111 with the floor surface G is enlarged compared to the contact area when the outsole is used as the standard sole shape. The anti-slip structure has wavy recesses 111a and elliptical recesses 111b. Multiple wavy recesses 111a are formed at predetermined intervals in the X-axis direction, and each of the multiple recesses extends in the Y-axis direction. Multiple elliptical recesses 111b are formed in the Y-axis direction between multiple adjacent wavy recesses 111a in the X-axis direction. The outsole bonding surface 112 is bonded to the midsole 12 in the rearfoot region BA and integrated. As shown in Figure 2, the outsole surface 113 has an outsole recess 113a in the center due to a depression. As shown in Figure 4, the outsole peripheral wall portion 114 rises from the area overlapping with the midsole 12 along the toe area. The outsole peripheral wall portion 114 has a higher rise in the area overlapping with the midsole 12 and the front of the outsole, and the area between them is connected by a smooth concave curve.

[0018] The midsole 12 is a sole component that ensures foot support rigidity in the rearfoot region BA, and is present only in the rearfoot region BA as shown in Figures 2 and 4 to 6. The midsole 12 is made of rigid TPU, which has the strength of hard plastic. TPU is an abbreviation for "Thermoplastic Polyurethane," and is a thermoplastic polyurethane elastomer. The midsole 12 has a midsole surface 121, a midsole bonding surface 122, a midsole peripheral wall portion 123, and a midsole reinforcing portion 124. The midsole 12 has an inner surface shape that wraps around the heel portion of the foot F in the rearfoot region BA in a manner that conforms to the shape.

[0019] As shown in Figure 2, the midsole surface 121 has a plurality of midsole recesses 121a in the bottom surface area corresponding to the sole of the foot in the rearfoot region BA. These midsole recesses 121a form a partial support surface continuous with the midsole surface 121. The midsole bonding surface 122 is bonded to the outsole 11 in the rearfoot region BA and becomes integrated. As shown in Figures 4 and 6, the midsole peripheral wall portion 123 rises along the outer circumference of the midsole surface 121. The height of the midsole peripheral wall portion 123 is highest at the heel of the foot F, and gradually decreases from the high heel towards the forefoot region FA. As shown in Figures 4 and 6(a), the midsole reinforcement portion 124 is formed by a plurality of triangular protrusions continuous along the entire outer circumference of the midsole peripheral wall portion 123.

[0020] As shown in Figure 1, the upper 20 comprises an upper body 21, an inner lining 22, a heel lining 23, a shoe tongue 24, shoelaces 25, a first strap 26, and a second strap 27. The upper body 21 is made of synthetic leather, which is easy to process and provides good strength. The upper body 21 has multiple ventilation holes 21a in its toe area to ensure breathability. The upper 20 has a double strap structure with a first strap 26 and a second strap 27 that are secured with hook-and-loop fasteners, making it easy for the wearer to adjust the tightness.

[0021] As shown in Figure 5, the sole cover 30 is fixed integrally with the upper 20 by sewing along the lower end of the opening of the upper 20. The sole cover 30 is formed in a planar shape and has a foot-shaped form that corresponds to the sole surface shape of the sole 10. This sole cover 30 is made of a soft TPU fabric material that is more flexible than the hard TPU material of the midsole 12 and has a flexible elasticity like rubber. The sole cover 30, which is fixed integrally with the upper 20 by sewing, has its bottom surface bonded to the sole surface of the sole 10 with adhesive. In other words, the lifting shoe 1 is manufactured by a sole assembly process, an upper assembly process, and a shoe assembly process. In the sole assembly process, the hard TPU midsole 12 is fixed to the hard rubber outsole 11 with adhesive. In the upper assembly process, the soft TPU sole cover 30 is pre-sewn to the upper 20. The shoe assembly process involves placing an adhesive between the bottom surface of the sole cover 30, which is sewn to the upper 20, and the surface of the sole 10, and then bonding and fixing them together by pressure using a press machine.

[0022] [Detailed configuration of the outsole forefoot (Figures 2, 8-10)] The outsole 11 has an outsole forefoot portion 110 in the forefoot region FA which includes the area corresponding to the MP joint α. The sole shape, bending rigidity, and dimensions of the outsole forefoot portion 110 are described below. The sole shape of the outsole forefoot portion 110 is set to have an enlarged sole portion 115 which expands the sole area outward from the outer circumference of the standard sole shape SS. The standard sole shape SS is the outer foot shape drawn along the outer shape of the wearer's foot F. The size of the enlarged sole portion 115 is determined to be sufficiently large, taking into account that there are variations in the standard sole shape SS due to individual differences among wearers, as shown by the hatching in Figures 2 and 8. In other words, the outsole forefoot portion 110 is shaped to absorb variations due to individual differences among wearers while forming a forefoot accommodating space that ensures free movement of the forefoot around the entire circumference of the outer circumference of the standard sole shape SS.

[0023] The bending stiffness of the outsole forefoot portion 110 is set to a stiffness that allows plantarflexion and dorsiflexion of the foot F from the MP joint α. Here, plantarflexion of the foot F refers to the movement of bending the portion from the MP joint α to the toes downward, as shown in Figure 10. Dorsiflexion of the foot F refers to the movement of bending the portion from the MP joint α to the toes upward, as shown in Figure 10. The sole configuration is such that the outsole 11 is present in the entire sole area SA, which is a combination of the forefoot area FA and the rearfoot area BA, and the midsole 12 is present only in the rearfoot area BA. Therefore, the bending stiffness of the outsole forefoot portion 110 is determined by setting the bending stiffness by combining the portion of the outsole 11 that extends forward from the end of the rearfoot area BA (sole area division line DL) where the midsole 12 is located, and the reinforcing plate 117 provided in the toe area, which will be described later.

[0024] The outsole forefoot portion 110 is equipped with a reinforcing plate 117 made of a material with higher hardness than high-hardness rubber in the toe area, which includes the region corresponding to the MP joint α. As shown in Figures 2 and 5, this reinforcing plate 117 is fitted and fixed into an outsole recess 113a formed in the outsole forefoot portion 110. The material of the reinforcing plate 117 is, for example, a carbon plate made of carbon resin. The depth dimension of the outsole recess 113a is equal to the thickness dimension of the reinforcing plate 117. As shown in Figure 8, when the region corresponding to the MP joint α is called the boundary region, the reinforcing plate 117 has a first plate portion 117a on the heel side of the boundary region, a second plate portion 117b on the toe side of the boundary region, and a plate connecting portion 117c at a position corresponding to the boundary region. The first plate portion 117a has a bifurcated shape that extends from the position of the MP joint α in an oblique outward direction and an inward direction of the foot width, respectively, to a position slightly beyond the sole area division line DL. The second plate portion 117b has a protruding shape that extends from the position of the MP joint α in an oblique outward direction of the foot width. The reinforcing plate 117 has the vertical bending rigidity of the first plate portion 117a set higher than that of the second plate portion 117b. The plate connecting portion 117c connects the first plate portion 117a and the second plate portion 117b at the outer part of the foot width, and its shape is set to a constricted shape with a smooth concave curve. In other words, if the plate shape of the reinforcing plate 117 were to be aimed only at increasing rigidity, the outer shape would be the outer shape including the dashed line, but by making it a constricted shape by removing the hatched portion 118 in Figure 8 from this outer shape, bending from the position of the MP joint α is promoted.

[0025] As shown in Figures 9 and 10, the enlarged sole width dimension FW of the outsole forefoot 110 is set to the standard sole width dimension SW of the standard sole shape SS, plus the inner enlarged width ΔWin and the outer enlarged width ΔWout. The inner enlarged width ΔWin is the width enlarged inward from the standard sole shape SS. The outer enlarged width ΔWout is the outer enlarged width enlarged outward from the standard sole shape SS. The outsole forefoot 110 has the added inner enlarged width ΔWin and outer enlarged width ΔWout portion designated as the enlarged sole portion 115. The enlarged sole portion 115 is set to a shape in which the inner enlarged width ΔWin and the outer enlarged width ΔWout gradually enlarge from the sole area division line DL toward the area corresponding to the MP joint α. In other words, the enlarged sole width dimension FW is set to be the widest dimension in the area corresponding to the MP joint α. Therefore, as shown in Figure 9, the cross-sectional structure of the region corresponding to the MP joint α is such that the inner surface of the sole with the expanded sole width dimension FW in the forefoot region FA where the MP joint α is located, and the inner surface of the upper 20 form a space to accommodate the MP joint. The space to accommodate the MP joint becomes a space that ensures the free movement of the MP joint α around the foot F. The starting position for expanding the sole width in the sole 10 is the position corresponding to the arch of the foot F where the sole width dimension is narrowest (the position shown by the dashed line at the bottom of Figure 8). Therefore, the sole 10 has a common expanded sole portion common to the outsole 11 and the midsole 12 in the range from the arch-corresponding position to the sole region division line DL.

[0026] As shown in Figure 8, a toe division line JL is set on the forefoot portion 110 of the outsole, dividing the toe area at a predetermined distance inward from the second toe position P1. The portion formed by reducing the sole width from the toe division line JL toward the toe is defined as the toe sole portion 116. Here, the toe division line JL is perpendicular to the toe centerline CL1, which originates from the second toe position P1 of the sole 10, and is set at a position a predetermined distance (for example, about 45 mm) toward the heel from the second toe position P1, which is the front tip of the outsole.

[0027] The sole shape of the toe sole portion 116 is such that the sole width at the toe division line JL is wider than the sole width at the toe division line JL according to the standard sole shape SS. The sole shape of the toe sole portion 116 is set so that the reduction ratio of the sole width from the toe division line JL toward the toe is less than the reduction ratio of the sole width of the standard sole shape SS. As shown in Figure 8, the sole shape of the toe sole portion 116 is determined to have sufficient width, taking into account that there are variations in the standard sole shape SS due to individual differences among wearers. Therefore, the sole cross-sectional structure of the toe sole portion 116 is such that it absorbs variations due to individual differences among wearers while forming a toe-accommodating space that ensures the free movement of the five toes. Furthermore, the space for the foot in the forefoot region (FA) is formed by the space for the metatarsophalangeal (MP) joint and the space for the toes. When converted to shoe size (JIS: Japanese Industrial Standards) based on foot circumference, which represents the circumference from the base of the big toe to the base of the little toe, this space is said to correspond to approximately 8E.

[0028] Specific examples of the dimensions of the toe sole portion 116 are set as follows, for example, when the foot dimension is L0, the dividing line dimension is L1, and the toe width dimension is L2: The foot dimension L0 is the length of the foot F from the shoe centerline CL0. The dividing line dimension L1 is the distance from the second toe position P1 to the toe dividing line JL. The toe width dimension L2 is the effective length dimension of the toe dividing line JL. L0:258.94mm, L1:45.05mm, L2:102.71mm L0:268.94mm, L1:45.03mm, L2:104.09mm L0:279.95mm, L1:45.00mm, L2:105.50mm L0:288.95mm, L1:45.01mm, L2:106.75mm Thus, as a concrete example of the dimensions of the toe sole portion 116, when the dividing line dimension L1 is set to a nearly constant dimension (approximately 45 mm), the longer the foot dimension L0, the longer the toe width dimension L2 is set to be.

[0029] The upper 20 comprises an upper body 21 that covers the forefoot portion 110 of the outsole, and a first strap 26 and a second strap 27 in the width direction of the foot. Here, when the forefoot portion 110 of the outsole and the upper body 21 bend from a position corresponding to the MP joint α, the bending position of the upper body 21 is hereinafter referred to as the "toe break position TP". Furthermore, the bending deformation region of the upper body 21 including the toe break position TP is hereinafter referred to as the "toe break region TPA" (see Figures 14 and 15). The second strap 27, which is positioned furthest towards the toes of the first strap 26 and second strap 27, is set to a position that avoids interference with the toe break region TPA, in other words, a position that does not interfere with the toe break region TPA. Here, toe break refers to the bending of the forefoot sole 10 and the upper 20. Furthermore, the fact that the second strap 27 and the toe break region TPA do not interfere means that they do not interfere in the vertical direction and the width direction of the foot.

[0030] [Background technology for lifting shoes (Figure 11)] Powerlifting is a sport in which competitors compete based on the total weight lifted in three events: squats, bench presses, and deadlifts. Squats are an event that primarily tests leg strength (the ability to stand), where a barbell is placed on the back and shoulders, and the athlete squats down to a specified depth and then stands back up. The following movements are performed: 1. Remove the barbell from the rack, hold it behind your back, and take a back step to a suitable position. 2. Keep your knees fully extended and maintain an upright posture, waiting for the referee's signal to "squat" (Figure 11(a)). 3. After the signal, bend your knees and squat down until the top of your thighs at the hip joint is lower than the top of your knees (Figure 11(b), (c)). 4. After standing up, straighten your knees and maintain an upright posture, waiting for the referee's "ruck" signal (Figure 11(d), (e)). 5. After the signal, return the barbell to the rack. In addition, because squats involve holding the barbell behind the back, they are sometimes called "back squats" in lifting competitions other than powerlifting and in other sports.

[0031] The characteristics of the squat movement in powerlifting competitions are as follows: Feature 1: The competition rules require deep bending and stretching. Because of the (extremely) heavy weight and the deep bending and straightening motion, the upper body will lean forward both when standing upright and during the movement (from bending down to standing up), as shown in Figure 11. Feature 2: There is no pushing off from the floor or ground, and no movement of the feet leaving the floor or ground. It is not necessary to completely lift the soles of your feet off the floor or ground during a backstep. Feature 3: Stability when standing is important. Maintaining an upright posture before and after bending and straightening movements is required.

[0032] Previous lifting shoes had the following problems: (1) A type that increases sole rigidity by inserting a carbon plate in the toe area, and narrows the sole and upper towards the toe to prevent the foot from wobbling inside the shoe (conventional product 1). Conventional product 1 has a structure that compresses the toes, causing the transverse arch formed at the MP joint of the foot to collapse. When the transverse arch collapses, the flexibility of the ankle joint is compromised, preventing the arch function of the sole of the foot from being fully utilized during backstepping and flexion / extension movements. As a result, conventional product 1 makes it difficult to maintain balance during backstepping and flexion / extension movements, making it difficult to stabilize the body and lift heavy weights in squats. The transverse arch will be explained in the section on the function of the arch of the foot below. (2) A type that allows for easy bending of the foot joint by securing space for the foot with the sole and upper in the toe area, but does not have a carbon plate in the toe area and has a soft material for the midsole in the forefoot (conventional product 2). This conventional model 2 lacks a carbon plate in the toe area and has a soft material in the forefoot midsole, causing the forefoot to twist to a certain extent from side to side inside the shoe as it sinks. As a result, the conventional model 2 causes the foot to wobble and lacks foot stability.

[0033] Thus, both conventional products 1 and 2 had a trade-off relationship between preventing foot instability and making it easier to bend the ankle joint. In other words, conventional products only had two options: either prioritize foot stability (foot fixation) by using a thick, rigid material, or prioritize ease of forefoot bending by using a thinner or softer material.

[0034] [Function of the arch of the foot (Figures 12-15)] First, as shown in Figure 12, the arches formed in the sole of the foot consist of a lateral longitudinal arch extending from the heel towards the ring toe, a medial longitudinal arch extending from the heel towards the big toe, and a transverse arch extending along the MP joint in the width direction of the foot. The main functions of the lateral and medial longitudinal arches are spring action, cushioning action, and balance action. The functions of the transverse arch are shock absorption, which absorbs impact applied to the foot from the sole, and foot stabilization, which is related to the rigidity (stability) of the foot and suppresses lateral wobbling of the foot.

[0035] Maximizing the function of the plantar arch reduces foot instability during backstepping and flexion / extension movements, and also maximizes the force pushing against the floor and ground reaction force during flexion / extension movements, allowing for heavier squats to be performed safely and in accordance with the rules. To maximize the function of the plantar arch, a wide toe box mechanism is desirable that does not compress the joints of the foot and the movement of the toes while maintaining the transverse arch and the medial and lateral longitudinal arches. Furthermore, to maximize the function of the plantar arch, it is desirable that the shoe's fold point (toe break position) when pushing the foot forward during backstepping bends from the MP joint, which allows for the foot's natural movement.

[0036] In contrast, conventional shoes (product 1), which have a carbon plate in the toe area to increase sole rigidity and a tapered toe, compress the toes. This reduces the height of the transverse arch, preventing the transverse arch from functioning properly and resulting in a lack of flexibility in the ankle joint to follow backstepping and knee flexion / extension movements. Furthermore, as shown in the comparative example (=conventional product 1) in Figure 13, conventional shoes (product 1) cause the foot to bend from around the proximal phalanx rather than the MP joint during backstepping, resulting in the toe break position being closer to the toes than the MP joint. In other words, with conventional shoes (product 1), the weight of the body and the barbell is concentrated on the very tip of the foot, close to the toes. In this state, the center of gravity is shifted forward during backstepping, requiring the use of calf muscles to compensate, which can lead to injury. Additionally, because the toes are compressed and the toe break position is closer to the toes, the center of gravity tends to remain in the forefoot even while maintaining an upright posture in preparation for flexion / extension after completing backstepping. If the center of gravity remains on the forefoot, the calcaneus becomes unstable, making it difficult to maximize the function of the plantar arch when standing upright and when squatting.

[0037] Conventional Model 2 shoes, with their wide toe box mechanism in the toe sole and upper, can ensure flexibility in ankle joint bending. However, Conventional Model 2 shoes do not have a carbon plate in the toe area and use a soft material in the midsole of the forefoot. As a result, part of the strap interferes with the bending deformation area of ​​the main body of the upper, causing the forefoot to sink in a twisted state to a certain extent in the width direction of the foot inside the shoe. Consequently, Conventional Model 2 shoes have the problem of the foot wobbling inside the shoe and lacking foot stability during backstepping and knee flexion and extension movements. In addition, because backstepping and knee flexion and extension movements are performed with the forefoot sinking in Conventional Model 2 shoes, it becomes difficult to maximize the function of the plantar arch during these movements. As a result, Conventional Model 1 shoes with a narrowed toe and Conventional Model 2 shoes with a wide toe box mechanism make it difficult to maximize the function of the plantar arch.

[0038] On the other hand, when using lifting shoes specifically for squats, there is no need to lift the entire sole of the foot off the floor or ground, whether during competition or training / practice by competitors or non-competitors. Therefore, durability against landing impact is not required for the shoes. Furthermore, because backstepping is performed with heavy weights on the back and shoulders, the toe break position of the shoe during backstepping needs to be optimized to allow for balance throughout the body without the center of gravity shifting forward, and to enable walking backward without the feet wobbling. In addition, to allow the transverse arch function to be utilized and to facilitate bending of the foot joints, the traditional Japanese zori sandal shape, which allows for barefoot-like movement of the toes, is ideal.

[0039] The inventors focused on the fact that it is important to maximize the arch function of the sole of the foot during backstepping and knee flexion and extension movements, and that the position of the MP joint is the optimal toe-break position when backstepping. They then discovered that in order to optimize the toe-break position and maximize the arch function of the sole of the foot, the sole shape of the shoe should be a wide toe-box mechanism that mimics the shape of a sandal. Therefore, the inventors developed a lifting shoe called a "wide toe-box shoe" that achieves both stability and ease of bending of the ankle joint, which were previously in a trade-off relationship. Here, a "wide toe-box shoe" refers to a shoe in which, when worn, there is sufficient space around the toes, all toes can move freely, and the toe-break position is at the position of the MP joint.

[0040] The inventors of the present invention have set the sole shape of the outsole forefoot portion 110 to a shape having an enlarged sole portion 115 in the lifting shoe 1, and have adopted a configuration that can produce appropriate flexibility at the position of the MP joint α. Therefore, the lifting shoe 1 provides foot stability by suppressing the wobbling of the foot F inside the shoe so that both feet supporting the weight load do not wobble during backstepping and knee flexion and extension movements. The lifting shoe 1 also provides ankle joint flexibility that ensures ease of bending of the foot from the MP joint α so that the center of gravity is optimized during backstepping and the force pushing against the floor surface G and the reaction force from the floor surface G are maximized during knee flexion and extension movements.

[0041] As shown in Figures 14 and 15, the lifting shoe 1 causes a toe break at the optimal toe break position TP, with the position of the MP joint α set as the optimal toe break position, allowing the foot F to bend appropriately from the MP joint α. The position of the toe break position TP varies depending on the size of the foot F, but it is approximately 70 mm from the toe position. Furthermore, the second strap 27 is positioned so as not to interfere with the toe break region TPA, which includes the toe break position TP, thereby enabling a toe break at the optimal toe break position TP. In addition, the reinforcing plate 117 has a plate connecting portion 117c that is set to a constricted shape with a smooth concave curve. This creates a bending stiffness difference where the bending stiffness of the plate connecting portion 117c is lower than that of the first plate portion 117a and the second plate portion 117b, promoting appropriate foot bending deformation from the MP joint α.

[0042] Therefore, the lifting shoe 1 allows for the use of the transverse arch function and enables movement with the rigidity (stability) of the outsole forefoot 110, allowing for stable backstepping without the foot wobbling and with an optimized center of gravity. Moreover, the lifting shoe 1 achieves both stability and flexibility in the ankle joint. As a result, the lifting shoe 1 maximizes the force pushing against the floor G and the ground reaction force from the floor G with the outsole forefoot 110 containing the reinforcing plate 117, both when squatting from an upright position and when standing up from a bent-knee position (squatting position). Therefore, compared to conventional products 1 and 2, it is possible to lift heavier barbells.

[0043] The foot stabilization effect provided by the transverse arch is achieved by setting the enlarged sole width dimension FW of the outsole forefoot 110 to a dimension obtained by adding the medial enlargement width ΔWin and the lateral enlargement width ΔWout to the standard sole width dimension SW of the standard foot shape, and by providing a reinforcing plate 117 in the toe area (see Figure 9). In other words, the outsole forefoot 110 has increased torsional resistance by ensuring a space that can be easily bent from the MP joint α, thereby exhibiting the transverse arch function. In addition, the outsole forefoot 110 is equipped with a reinforcing plate 117 that increases rigidity in the toe area, including the region corresponding to the MP joint α, thereby suppressing sinking when the foot F is twisted inward or outward. As a result, instability in the width direction of the foot is suppressed during squats under heavy loads, and foot stability is ensured.

[0044] Furthermore, the toe sole portion 116 widens the sole width of the toe division line JL compared to the sole width of the toe division line JL according to the standard sole shape SS. In addition, the toe sole portion 116 is set to have a sole shape in which the reduction ratio of the sole width from the toe division line JL toward the toe is smaller than the reduction ratio of the sole width of the standard sole shape SS. As a result, the toe sole portion 116 ensures space for the five toes to be easily bent from the toe joints and for the five toes to be spread apart.

[0045] Thus, the lifting shoe 1 exhibits transverse arch function by setting an enlarged sole width dimension FW in the forefoot portion 110 of the outsole, thereby creating a space to accommodate the MP joint α around the foot F, ensuring free movement of the MP joint α. Furthermore, the lifting shoe 1 exhibits lateral longitudinal arch function and medial longitudinal arch function by setting the shape of the toe sole portion 116, which creates a space to accommodate the toes, allowing for easy bending and free movement of the five toes from the MP joints. Therefore, the lifting shoe 1 can maximize the function of the plantar arch by exhibiting all three functions: transverse arch function, lateral longitudinal arch function, and medial longitudinal arch function.

[0046] [Effects of weightlifting shoes] The lifting shoe 1 of Embodiment 1 can achieve the following effects.

[0047] (1) The lifting shoe 1 comprises a sole 10 and an upper 20 fixed to the sole 10 and covering the upper part of the wearer's foot. The sole 10 has a sole area division line DL set at a position closer to the heel than the MP joint α, which flexes at the position between the metatarsal bones and phalanges at the base of the toes of the foot F, and the sole area division line DL divides the entire sole area SA into a toe-side forefoot area FA and a heel-side hindfoot area BA. The sole 10 has an outsole 11 having a contact surface 111 for the floor surface G or ground, and a midsole 12 fixed on the outsole 11. The outsole 11 has an outsole forefoot portion 110 in the forefoot area FA which includes the area corresponding to the MP joint α. The outsole forefoot portion 110 is set to have an enlarged sole portion 115 which expands the sole area outward from the outer circumference of the reference sole shape SS, when the outer circumference foot shape drawn along the outer shape of the wearer's foot F is the reference sole shape SS. These lifting shoes 1 can achieve both foot stability and flexibility in ankle joint movement while walking and flexing / extending the knees while supporting a weight load with both feet.

[0048] (2) The outsole 11 is present in the entire sole area SA, which is the sum of the forefoot area FA and the rearfoot area BA. The midsole 12 is present in the rearfoot area BA. The forefoot portion 110 of the outsole is set to have a bending stiffness that allows plantarflexion and dorsiflexion of the foot F from the MP joint α. This lifting shoe 1 allows for free plantarflexion and dorsiflexion of the foot F due to the setting of the bending stiffness of the forefoot portion 110 of the outsole. As a result, when bending the foot F under heavy load, it is possible to ensure appropriate bending from the position of the MP joint α, which is the natural movement of the foot.

[0049] (3) The outsole material shall be high-hardness rubber. The forefoot portion 110 of the outsole shall be equipped with a reinforcing plate 117 made of a material with higher hardness than the high-hardness rubber in the toe area, which includes the area corresponding to the MP joint α. In this lifting shoe 1, the reinforcing plate 117 performs several functions in combination: adjusting the bending stiffness of the forefoot area FA of the outsole 11, suppressing sinking in the twisting state of the foot F, and improving the force pushing against the floor surface G and the ground reaction force from the floor surface G.

[0050] (4) The reinforcing plate 117 has a first plate portion 117a on the heel side of the boundary region corresponding to the MP joint α, and a second plate portion 117b on the toe side of the boundary region. The reinforcing plate 117 has a vertical bending rigidity of the first plate portion 117a that is higher than the vertical bending rigidity of the second plate portion 117b. The plate shape of the reinforcing plate 117 is such that the shape of the plate connecting portion 117c that connects the first plate portion 117a and the second plate portion 117b is set to a constricted shape. This lifting shoe 1 promotes proper foot bending deformation from the MP joint α by setting the shape of the plate connection portion 117c of the reinforcing plate 117 to a constricted shape.

[0051] (5) The forefoot portion of the outsole 110 has an enlarged sole width dimension FW which is the sum of the standard sole width dimension SW of the standard sole shape SS, the inner enlarged width ΔWin which is enlarged inward from the standard sole shape SS, and the outer enlarged width ΔWout which is enlarged outward from the standard sole shape SS. The enlarged sole portion 115 is set to have a shape in which the inner enlarged width ΔWin and the outer enlarged width ΔWout gradually enlarge from the sole area division line DL toward the area corresponding to the MP joint α. This lifting shoe 1 has a space that accommodates the MP joint α, which can be easily bent from the MP joint α, and the position of the MP joint α can be set to the toe break position TP, thereby enabling the transverse arch function to be exerted.

[0052] (6) The outsole forefoot portion 110 has a toe division line JL set at a predetermined distance inward from the front tip of the outsole, and the portion formed by reducing the sole width from the toe division line JL toward the toe is the toe sole portion 116. The sole width of this toe sole portion 116 is made wider than the sole width of the toe division line JL according to the standard sole shape SS, and the ratio of reduction in sole width toward the toe from the toe division line JL is set to be less than the ratio of reduction in sole width of the standard sole shape SS. These lifting shoes 1 have a toe-receiving space that allows five of the toes of the foot F to be easily bent from the MP joint α and to move freely, and the function of the plantar arch is maximized by the activation of the transverse arch function, the lateral longitudinal arch function and the medial longitudinal arch function.

[0053] (7) The upper 20 is provided with at least one strap (first strap 26, second strap 27) in the width direction of the foot. The strap (second strap 27) is set in a position that avoids interference with the toe break area TPA in front of and behind the position where the upper 20 bends from the position corresponding to the MP joint α. In this lifting shoe 1, the strap (second strap 27) does not hinder the bending of the upper 20 from the position corresponding to the MP joint α, and bending from the MP joint α is ensured.

[0054] (8) The upper 20 is integrally fixed along the lower end of the opening facing the sole 10 and includes a sole cover 30 whose shape corresponds to the sole surface shape of the sole 10. The sole cover 30 is made of a material more flexible than the material of the midsole 12 and its bottom surface is adhesively bonded to the sole surface of the sole 10. In these lifting shoes 1, a sole cover 30 is attached to the surface of the sole 10, which reduces the pain caused by the unevenness of the sole surface to the soles of the feet, thereby improving the comfort of use.

[0055] The above description is based on the drawings of the lifting shoe 1 of Embodiment 1. However, the specific configuration of the shoe of this disclosure is not limited to the configuration shown in Embodiment 1. Modifications and additions to the design of the shoe of this disclosure are permitted as long as they do not depart from the gist of the invention as described in each claim of the patent claims.

[0056] Embodiment 1 shows an example where the sole area division line DL is set at a position on the heel centerline CL2 that is closer to the heel than the MP joint α, and is a line perpendicular to the heel centerline CL2. However, the sole area division line is not limited to this example, and may also be set at a position on the shoe centerline that is closer to the heel than the MP joint, and is a line perpendicular to the shoe centerline. Alternatively, the sole area division line may be set at a position on the toe centerline that is closer to the heel than the MP joint, and is a line perpendicular to the toe centerline. Furthermore, the sole area division line may be set not only as a straight line, but also as a bent line, a curve, etc.

[0057] Embodiment 1 shows an example in which a high-hardness rubber outsole is provided with a reinforcing plate 117 made of a material harder than the high-hardness rubber material in the toe portion, including the area corresponding to the MP joint α of the forefoot portion 110 of the outsole. However, the outsole may also be an example without a carbon plate. In the example without a carbon plate, the outsole material selection, sole thickness setting, sole shape setting, etc., are used to perform functions such as adjusting bending rigidity, suppressing sinking, and improving ground reaction force.

[0058] Embodiment 1 shows an example in which the shape of the plate connecting portion 117c on the outer side of the foot width of the reinforcing plate 117 is set to a constricted shape on one side with a smooth concave curve. However, the shape of the carbon plate is not limited to this. For example, the shape of the plate connecting portion on the inner and outer sides of the foot width of the carbon plate may be set to a constricted shape on both sides. Alternatively, the shape of the plate connecting portion may be set to a constricted shape with a jagged pattern formed along the concave shape, instead of a smooth concave curve. Furthermore, the shape of the plate connecting portion may be set to a constricted shape with a straight triangular recess, instead of a smooth concave curve.

[0059] Embodiment 1 shows an example in which a sole cover 30 made of a material more flexible than the midsole 12 is adhesively bonded to the sole surface of the sole 10 at the bottom surface of the cover. However, the example is not limited to the adhesive bonding of the sole cover 30 to the sole surface; for example, an insole, which is an accessory component that can be attached detachably, may be attached on top of the sole cover. In this example of attaching an insole, multiple types of insoles with different thicknesses and sizes can be prepared in advance so that the wearer can select one according to their preference.

[0060] Embodiment 1 shows an example of application to lifting shoes. However, the shoes are not limited to lifting shoes such as those used in powerlifting or weightlifting. For example, the shoes may be other sports shoes or indoor shoes where there is little movement of pushing off the floor or ground with the foot, and where cushioning and shock absorption are not important. [Explanation of Symbols]

[0061] 1. Lifting shoes (an example of shoes) 10 soles 11 Outsole 110 Outsole forefoot 111 Contact surface 113 Outsole surface 115 Enlarged sole section 116 Toe sole section 117 Reinforcement Plate 117a First plate section 117b Second plate section 117c Plate connection section 12 Midsole 121 Midsole surface 20 Upper 26 First Strap 27 Second strap 30 Sole Covers G Floor surface F foot α MP joint DL Sole Area Boundary Line SA Sole All Area FA forefoot area BA hindfoot area SS standard sole shape FW Expanded sole width dimensions SW standard sole width dimensions ΔWin Inner width expansion ΔWout Outer width expansion P1 Toe position JL Toe Divider

Claims

1. A shoe comprising a sole and an upper fixed to the sole and covering the upper part of the wearer's foot, The sole has a sole area division line set at a position closer to the heel than the MP joint, which flexes at the base of the toes between the metatarsal bones and phalanges, and the entire sole area is divided into a forefoot area on the toe side and a hindfoot area on the heel side by this sole area division line. The sole comprises an outsole having a contact surface with the floor or ground, and a midsole fixed on top of the outsole. The outsole has an outsole forefoot portion in the forefoot region which includes the region corresponding to the MP joint, The forefoot portion of the outsole is set to have an enlarged sole portion, where the sole area is increased outward from the outer circumference of the reference sole shape, when the outer circumference foot shape drawn along the outer shape of the wearer's foot is used as the reference sole shape. Shoes characterized by the following features.

2. In the shoes described in claim 1, The outsole is present in the entire area of ​​the sole, including the forefoot area and the rearfoot area. The midsole is located in the rearfoot region, The forefoot portion of the outsole is set to have a bending stiffness that allows for plantarflexion and dorsiflexion of the foot from the MP joint. Shoes characterized by the following features.

3. In the shoe according to claim 2, The outsole material is a high-hardness rubber material. The forefoot portion of the outsole is provided with a reinforcing plate made of a material with higher hardness than the high-hardness rubber material in the toe area, including the region corresponding to the MP joint. Shoes characterized by the following features.

4. In the shoes described in claim 3, The reinforcing plate has a first plate portion on the heel side of the boundary region corresponding to the MP joint, and a second plate portion on the toe side of the boundary region. The reinforcing plate is configured such that the vertical bending rigidity of the first plate portion is higher than that of the second plate portion. The plate shape of the reinforcing plate is such that the shape of the plate connecting portion that connects the first plate portion and the second plate portion is set to a constricted shape. Shoes characterized by the following features.

5. In the shoes according to claim 4, The forefoot portion of the outsole has an enlarged sole width dimension which is the sum of the standard sole width dimension of the standard sole shape, an inward enlarged width which is an inward enlargement from the standard sole shape, and an outward enlarged width which is an outward enlargement from the standard sole shape. The enlarged sole portion is shaped such that the inner and outer widths of the enlarged portion gradually increase from the sole region division line toward the region corresponding to the MP joint. Shoes characterized by the following features.

6. In the shoe according to claim 5, When the forefoot portion of the outsole has a toe division line set at a predetermined distance inward from the front tip of the outsole, and the portion formed by reducing the sole width from the toe division line toward the toe is defined as the toe sole portion, The toe sole portion is configured such that the sole width of the toe division line is wider than the sole width of the toe division line according to the standard sole shape, and the reduction ratio of the sole width from the toe division line toward the toe is less than the reduction ratio of the sole width of the standard sole shape. Shoes characterized by the following features.

7. In the shoes according to any one of claims 1 to 6, The upper is provided with at least one strap in the width direction of the foot, The strap is positioned to avoid interference with the front and rear toe break areas, including the position corresponding to the MP joint, when the upper bends from that position. Shoes characterized by the following features.

8. In the shoes according to claim 7, The upper is integrally fixed along the lower end of the opening facing the sole and includes a sole cover having a shape that conforms to the sole surface shape of the sole. The sole cover is made of a material more flexible than the midsole material, and its bottom surface is bonded to the sole surface of the sole. Shoes characterized by the following features.

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