A shoe, and a method of manufacturing a shoe

Abstract

A shoe comprising a sole with a ground-engaging surface for engaging a ground; an edge; and a connecting portion interconnecting and extending between the ground-engaging surface the edge. At least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first one of which has first material properties, and a second one of which has second material properties. The two adjacent elements are disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground. The adjacent elements are deflectable relative to one another such that application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and such that application of the force component to the selected portion in a second direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the first coefficient of friction.

Description

Field of the invention

[0001] The present invention generally relates to a shoe, such as a sport shoe, tailored to reduce the risk of injuries, compensate disability, and enhance performance. The invention also relates to a method of manufacturing a shoe.Background of the invention

[0002] It has been estimated that ankle injuries account for 15-30% of all injuries in sport.

[0003] An estimated 70-80% of athletes who suffer a sprain will have repeated problems. Functional ankle instability and sprains reoccur in about 10-60 % of athletes previously subject of acute injury. In these patients a part of the mechanism that causes re-injury is an erroneous sensation of the position of the ankle joint in plantar flexion 30° / inversion 20° whereby the joint can be more plantar-flexed and inverted when landing thus creating a risk of lateral distortion.

[0004] Ankle injuries typically occur when the ankle twists uncontrolled in an inversion / supination and possibly plantar flexion motion. This results in a lateral sprain (distortion) but fractures also occur frequently. The sprain causes damage to the calcaneofibular ligament and the talofibular anterior ligament in varying degrees and possibly the tibiofibular anterior ligament as well as the joint capsule and surrounding soft tissue.

[0005] The injuries can also be treated with taping or semi rigid braces but both methods have significant limitations as they provide a limited support especially for repeated injuries and often degrades freedom of movement for the wearer. Also, the restricting effect of tape is lost after varying periods of exercise (Am J Sports Med November 2010 vol. 38 no. 11 2194-2200).

[0006] From a shoe design point of view, prevention of sports injuries has hitherto generally focussed on stability increase of shoes, enhancement of foot support, as well as on improvement of anti-slip properties of shoes. Despite past efforts, it has however been found that a need remains for further development of a shoe which contributes to reducing the occurrence of sports injuries, notably ankle and knee injuries.

[0007] International patent publication No. WO 2016 / 207381 discloses a shoe having an area of reduced friction with a view to reducing the ability of the user's foot to rotate relative to ground (inversion and internal rotation) when the load of the user's body is shifted towards or lands near an edge of the shoe. Whilst the invention of WO 2016 / 207381 constitutes an improvement over the state of the art at the time the invention was made, a further need for improvement has arisen.

[0008] Secondly, the invention is developed to prevent falls, which globally are a major public health problem for people with various gait impairments (disabilities, diseases, age, pressure related pain, overuse injuries) and often has many consequences for both the individual and the public. The personal consequences can be fractures which results in long recoveries, and a worsening of life quality. In some cases, a fall can even result in fatality due to head trauma or long recoveries. Besides the personal consequences, treatment of a fall has high costs for society and the healthcare system.

[0009] Falls often occur due to tripping, which is characterized by unanticipated increased braking force in the anterior region of the shoe and sole. This typically happens when taking a short step or hitting the ground with the tip of the shoe when correcting your walk as a result of a disruption. The resulting brake force results in overbalance. If the brake force reaches a certain threshold, there is no longer a possibility for regaining control over your balance, which will result in a fall.

[0010] In some gait impairments a plantar flexion and inverted foot position is seen, which results in an anterior and lateral pressure distribution during foot strike. This gait pattern will, besides the increased risk of falling, also cause pain in the foot due to the high plantar pressure.Description of the invention

[0011] It is an object of embodiments of the invention to provide an improved shoe, such as improved sports shoe. It is in particular an object of embodiments of the invention to provide a shoe which enhances its grip relative to the ground in circumstances when a solid grip is desired, and which enhances slip relative to the ground in circumstances when low friction properties relative to the ground are desired.

[0012] According to a first aspect, the invention provides a shoe comprising:. a sole with a ground-engaging surface for engaging the ground; an edge; and a connecting portion interconnecting and extending between the ground-engaging surface and the edge; wherein: at least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first one which has first material properties, and a second one of which has second material properties, the two adjacent elements being disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground, commonly referred to as a "horizontal force"; and the adjacent elements are disposed, configured and deflectable relative to one another such that: application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and application of the force component to the selected portion in a second direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the second coefficient of friction.

[0013] In the present context, injuries should be understood to include, but not be limited to sprains, including syndesmosis ruptures, dislocations, strains, and fractures. Injuries could also be understood to include osteochondral lesions. In the context of falling prevention various trauma might result such as contusions, fractures and concussion or haemorrhage. In the context of overuse injuries these are fasciitis, tendinitis, tendinopathies, bursitis, and stress fractures. Pressure related injuries and disability includes diabetic and other ulcers, osteoarthritis pain from foot, knee and hip and pain due to pes planus, overpronation and similar conditions.

[0014] In the present context, the ground-engaging surface should be understood to be that part of the shoe which engages the ground when the wearer of the shoe is standing up straight and puts equal weight on both feet. The ground-engaging surface may differ from the part of the shoe that engages the ground during movement of the wearer such as jumping, landing, turning, etc.

[0015] In the present context, the edge is to be understood as extending from the connecting portion in a direction away from the ground-engaging surface and the connecting portion, the edge extending in a direction transverse, i.e. not parallel, to the ground-engaging surface.

[0016] At least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first element which has first material properties, and a second element which has second material properties. The first and second material properties may in particular include at least one of surface friction properties and Young's Modulus. Differences in surface friction properties may be achieved by differences in geometries, such as differences in surface roughness, or through selection of different materials or different material compositions for the elements. The two adjacent elements are disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground, i.e. a horizontal force. Thus, the two adjacent elements may be arranged in contact with each other or alternatively adjacent to each other without contact, whereby subjection of a force component parallel to the ground to the selected portion; i.e. to at least one of the elements, will result in deflection of the elements relative to one another. By deflection of the elements relative to each other at least one of the elements is deflected.

[0017] Due to the ability of the first and second elements to deflect relative to each other, the force component may decrease or increase the extent of each of the elements' contact surface area with the ground, depending on the direction of the force component. The differences between the first and second material properties, such as in particular, for example, different friction properties, thereby confer different coefficients of friction between the selected portion and the ground, depending on the extent of the elements' overlap with the ground, which in turn depends on the direction of the force component. It may thus be achieved that the selected portion's grip relative to ground is enhanced in circumstances when a solid grip is desired, and that the selected portion's slip properties relative to ground, i.e. the selected portion's ability to slide relative to ground, increase in circumstances when low friction properties are desired.

[0018] In particular, on the one hand, low friction properties of the selected portion may be desired with a view to enable the shoe to slide parallel to its underlying surface during a shift of the user's weight outwardly or forwardly when no realignment of the user's body can be achieved, i.e. when a force component in a lateral or forward direction is applied. The amount of energy transferred to user's foot and leg anatomy and further up the kinetic chain, resulting from the shoe's ground grip may thus be reduced. In some incidents, the user may fall due to loss of grips, but the risk of general injury, however, reduces relative to the risk that would have existed if the selected portion of the shoe had maintained its grip relative to ground. In these cases, loss of grip may also enhance performance in some athletic shoes used for handball, football, floorball or dance as it allows the user to go into the splits with minimum force to overcome in an element is applied to the heel portion of the shoe.

[0019] On the other hand, high friction properties of the selected portion may be desired with a view to enabling a firm grip between the shoe and ground when the user's body is in balance, such as when the user pushes off for a jump or a step. Under such circumstances the direction of the force component to the selected portion is different from the force component applied when the user is out of balance. In particular, when pushing off for a jump or a step or when striving for realignment, the force component is generally inwardly directed towards the centre of pressure on the shoes. Under such circumstances, the shoe's grip relative to ground should generally be firm, i.e. a relative high coefficient of friction is desirable in order to ensure stability and balance compared to the relatively low coefficient of friction which is desirable when the force component is in an outward direction away from the foot's centre of pressure. It should be understood that the first and second elements may be embodied as a single structural entity, the properties of which depend upon the direction of a force component applied to such single structural entity. For example, flexible, deformable and / or movable protrusions may be provided to an outer surface portion of such entity, whereby a protrusion distance (or height) and / or an angle of such protrusions relative to an underlying support surface may vary with the direction and / or magnitude of an applied force, which thereby control frictional properties of the selected portion of the shoe.

[0020] In one embodiment, an air gap is arranged between the first and second element. In an alternative embodiment, an air gap may be arranged between a part of the first and second element which may also be in contact with each. In a further alternative embodiment, the first and second elements may be in contact with each other along their abutting surfaces.

[0021] The adjacent elements are disposed, configured and deflectable relative to one another such that application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and such that application of the force component to the selected portion in a second direction being different from the first direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the first coefficient of friction.

[0022] Consequently, it may be achieved that friction is reduced when the selected portion is subjected to the force component in the first direction and that friction is not reduced when the selection portion is subjected to the force component in the second direction, where the first coefficient of friction is lower than the second coefficient of friction. It should be understood, that the opposite case may also be applicable, so that friction is reduced when the selected portion is subjected to the force component in the second direction; i.e. when the second coefficient of friction is lower than the first coefficient of friction. Thus, the use of the terms first direction and second direction are not limiting, and can be oppositely applied.

[0023] The first element and the second element are disposed to enable deflection of the first and second element relative to each other. The first and second elements may be arranged relative to each other so that application of a force component in the first direction increases contact between the first element and ground and may reduce contact between the second element and ground, whereby the first coefficient of friction may be the dominant friction. On the contrary may application of a force component in the second direction increase contact between the second element and ground and may reduce contact between the first element and ground, whereby the second coefficient of friction may be the dominant friction.

[0024] When the first coefficient of friction is lower than the second coefficient of friction, friction between the selected portion and ground is lower when the selected portion is subjected to the force component in the first direction than friction between the selected portion and ground when the selection portion is subjected to the force component in the second direction.

[0025] The reduction of friction may prevent ankle sprains as most sprains happen with the foot in contact with the ground during landing or other movements at which the foot interacts with ground in an unpredicted or unbalanced manner, such as when the foot lands on an opponent's foot or positions itself incorrectly relative to ground. Moreover, the selected portion when reducing friction may ensure increased mobility of the shoe when the area of reduced friction is in contact with the ground thus preventing the shoe from remaining at an undesirable position relative to ground. Instead, the shoe is enabled to slide parallel to its underlying surface or reducing undesirable translational and rotational forces such as in- / eversion of the foot, in / external rotation with sprain risk due to harmful subsequent transferral of kinetic energy to the kinetic chain and surrounding tissues and decreased sports performance due to suboptimal positioning for muscle force generation. Also, unwanted braking force on the edge of the shoe will affect performance negatively, e.g. in turning and sideways movement. Such adverse effects are diminished by the lowered friction in the direction of the shoe movement. Accordingly, the effect will increase sliding in, e.g., tennis and enhance safety of this movement in tennis.

[0026] The elements can also be used for pressure regulation to potentially reduce maximum pressure. By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against injury, maintain full performance and compensate disability. In the context of a sideways directed translational and rotational forces this will have a preventive effect on knee sprains.

[0027] Deflection of the first and second element relative to each other may be achieved by forming the first element of a first material being less flexible and / or having a higher elasticity than a second material of which the second element is formed. Additionally, or alternatively, the first material may have a lower surface friction when the force component is in the first direction. As mentioned above, this first and second material may be oppositely selected.

[0028] The first material properties may thus comprise at least one of a Young's modulus and a first surface friction, and the second material properties may comprise at least one of a second Young's modulus and a second surface friction.

[0029] It should be understood, that the first element and / or the second element may be formed of a plurality of materials, where first and second material properties are the resulting material properties for each respective one of the first and second elements.

[0030] Thus, in one embodiment, the first of at least one selected portion of the sole, the edge or the connecting portion having first material properties comprises a first material and the second of at least one selected portion of the sole, the edge or the connection portion having second material properties comprises a second material, wherein the first material comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA), polyethylene such as ultra-high-molecular-weight polyethylene (UHMW-PE), synthetic rubbers, such as styrene-butadiene rubber (SBR), Styrene Butadiene Styrene, nylon or mixtures thereof with a Shore D hardness 40 or higher, and wherein the first material further comprises an additional material selected from the list comprising polymerized polysiloxanes such as polymerized silicone, polyethylene such as ultra-high molecular (UHMW) siloxane polymer, per- and polyfluoroalkyls (PFAS) such as polytetrafluoroethylene (PTFE), graphene, graphite or mixtures thereof.

[0031] The second material comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA)" or mixtures thereof with a Shore A hardness 50-85.

[0032] The second material is typically selected from any conventional shoe sole material. The method of measurement of Shore hardness measures the depth of indentation in the material created by a given force on a standardized presser foot. Shore A hardness is typically measured by an indenting foot having a hardened steel rod having 1.1 mm-1.4 mm diameter, with a truncated 35° cone and 0.79 mm diameter. The applied mass is typically 0.822 kg, which results in a force (N) of 8.064.

[0033] Shore hardness D is typically measured by an indenting foot having a hardened steel rod having 1.1 mm-1.4 mm diameter, with a truncated 30° conical point and 0.1 mm radius tip. The applied mass is typically 4.550 kg, which results in a force (N) of 44.64.

[0034] As it is understood by the skilled person, a material having a Shore Hardness A 50-85 is considered to be a softer material than a material having a Shore Hardness D 40 or higher.

[0035] The first material is considered to be low friction in comparison to the second material, which, in the context of the present invention is considered to be a high friction material.

[0036] According to the invention, it is possible to provide a first material, such as TPU having a Shore Hardness D 40 or higher in combination with polymerized siloxanes, such as polymerised silicone. However, it is also possible to provide a first material, such as TPU having a Shore Hardness D 40 or higher in combination with graphene and / or PTFE to provide the low friction material. Accordingly, a first material may be provided such that silicone is absent and only e.g., PTFE and / or graphene is present.

[0037] Due to the first and second material having different friction coefficients, a multi-frictional composition is provided. The multi-frictional composition typically comprises a first material having first friction properties and a second material having second friction properties. Preferably, the first material has a friction coefficient less than 0.7 as measured in shoe friction test (ISO 13287:2012). The second material has high friction with a friction coefficient of more than 0.7 as measured in shoe friction test (ISO 13287:2012).

[0038] The first material has a Shore D hardness of 40 or more as defined by ASTM 2240. An example of such suitable first material is Elastollan ®< 1174D (BASF Chemical Company), which has a Shore D hardness of 74.

[0039] The weight% of the additional material is between about 5-30% based on the total weight of the first material, preferably about 15-25%, more preferably about 20-22% and most preferably about 20% based on the total weight of the first material.

[0040] An example of an additional material is MB 50-017 Masterbatch (Dow Corning ®< ) which comprises 50% of ultra-high-molecular-weight (UHMW) siloxane polymer dispersed in thermoplastic polyurethane (TPU) but other suitable commercially available materials may also be used.

[0041] In some embodiments, the composition comprises e.g., TPU having Shore hardness D 40 or higher and e.g., UHMW siloxane polymer.

[0042] The second material and the sole of the shoe are integrally formed from one and the same sole material. The first material may have a lower surface friction than the second material when the force component is in the second direction.

[0043] The elements may be configured such that a surface friction of the selected portion is dependent on the height of the elements relative to each other. In particular, one of the elements may deflect more than the other one when subjected to pressure to thereby render the surface friction of the selection portion dependent from the amount of pressure applied.

[0044] In one embodiment, each of the first and second elements may define outwardly facing surfaces, each of which defines a portion of an outer surface of the sole, the connecting portion and / or the edge of the shoe. The first element may have a Young's modulus of a first value and a first surface roughness and / or a first coefficient of friction on its outwardly facing surface, and the second element may have a Young's modulus of a second value and a second surface roughness and / or a second coefficient of friction on its outwardly facing surface; where the value of the first Young's modulus is higher than the value of the second Young's modulus, and the first surface roughness is lower than the second surface roughness. In this embodiment, the friction is reduced when the selected portion is subjected to the force component in the first direction and friction is not reduced when the selection portion is subjected to the force component in the second direction.

[0045] As mentioned above, the value of the first Young's modulus may be lower than the value of the second Young's modulus, and the first surface roughness and / or the first coefficient of friction may be higher than the second surface roughness and / or the second coefficient of friction, respectively, in an alternative embodiment.

[0046] As an example, the first element may define one or more outwardly facing surfaces of the connecting portion and the edge of the shoe, whereas the second element may define one or more outwardly facing surfaces of an outer surface of the sole and the connecting portion. In an alternative example, both the first element and the second element may define one or more outwardly facing surfaces of an outer surface of the sole and of the connecting portion and of the edge of the shoe.

[0047] It should be understood, that other combinations may be applicable in other embodiments, where each of the first and second elements may define outwardly facing surfaces, each of which defines a portion of an outer surface of the sole and / or the connecting portion and / or the edge of the shoe.

[0048] In the present context, a sports shoe may be understood as a shoe suitable for wear when engaging in various forms of indoor and / or outdoor sports activities such as football, basketball, volleyball, handball, floorball, tennis, badminton, dancing, table tennis, fitness, etc. Such shoe may also be referred to as an athletic shoe.

[0049] In the context of the present invention, the shoe may also be a safety shoe, a casual shoe or an orthopaedic shoe.

[0050] The shoe may define a foot part and a leg part, wherein the leg part extends no longer than a distance equal to one third of the distance from a wearer's knee to the farthest end of the wearer's heel. In this case, the shoe may be particularly suitable for use as a sports shoe because it may allow sufficient limb mobility for the wearer of the shoe to perform sports. In the present context, the foot part is to be understood as the part of the shoe encompassing the wearer's foot. The leg part is to be understood as the part of the shoe vertically extending between the surface of the wearer's heel furthest from the wearer's knee and the part of the shoe closest to the wearer's knee. As such, the foot part and the leg part of the shoe overlap.

[0051] The shoe may define a foot part and a leg part, wherein the leg part extends no longer than 1.25 times the longest straight-line extend of a wearer's foot. Thus, the height of the leg part is thus at most equal to 1.25 times the length of the foot part, or at most equal to the length of the foot part, or smaller than then length of the foot part. The height of the leg part is preferably measured as a straight-line distance from the bottom of the sole of the shoe to an uppermost edge of the shoe for circumferentially surrounding the wearer's leg. In such embodiments, the shoe may be particularly suitable for use as a sports shoe because it may allow sufficient limb mobility for the wearer of the shoe to perform sports. In present context, the foot part is to be understood as the part of the shoe encompassing the wearer's foot. The leg part is to be understood as the part of the shoe vertically extending between the surface of the wearer's heel furthest from the wearer's knee and the part of the shoe closest to the wearer's knee. As such, the foot part and the leg part of the shoe overlap. The longest straight-line extend of the wearer's foot is commonly equal to the distance between the furthest ends of the wearer's toes and heel parallel to ground when the wearer is standing up.

[0052] The selected portion may be flush with the surrounding areas of the shoe. In other words, selected portion may be arranged to not protrude from the surrounding areas of the shoe. In this case, the shape of the shoe may be essentially similar to the shape the shoe would have, if the shoe did not comprise the selected portion.

[0053] In embodiments of the present invention, the outwardly facing surface of the first element preferably defines a first coefficient of friction of less than 0.7 as tested according to ISO 13287:2012 by providing a forepart of a sole of a test shoe as according to ISO 13287:2012 with the first material properties and using the backward slip on the forepart test without lubricant as according to ISO 13287:2012. The outwardly facing surface of the second element preferably defines a second coefficient of friction of more than 0.7 as tested according to ISO 13287:2012 by providing a forepart of a sole of a test shoe as according to ISO 13287:2012 with the second material properties and using the backward slip on the forepart test without lubricant as according to ISO 13287:2012.

[0054] It should be understood that the first coefficient of friction may be different for different parts of outwardly facing surface of the first element and the second element, respectively. The friction coefficient may gradually change within the outwardly facing surface(s). The different first coefficients of friction and / or second coefficients of friction may be provided by a plurality of materials and / or varying surface frictions of the first and / or second element.

[0055] The first element may be comprised in at least one insert secured to a portion of the sole of the shoe. The at least one insert may form one or more outwardly facing surfaces which may each define a portion of an outer surface of the sole, and / or of the connecting portion and / or of the edge of the shoe.

[0056] The second element may be integrated with the sole of the shoe. In one embodiment, the second element and the sole of the shoe, except for the first element, are integrally formed from one and the same sole material. Thus, the second element may constitute a part / parts of the sole.

[0057] With a view to securing a durable mechanical structure of the selected portion, the at least one insert may be co-moulded with the sole material. This may be achieved by moulding the sole material onto the at least one insert. This may be especially applicable when using a sole material having a lower Young's modulus than the material of the at least one insert.

[0058] In one embodiment, the at least one insert may comprise a downward facing surface portion defining a portion of the sole of the shoe and a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. Consequently, the application of the force component in a first direction may result in a lower coefficient of friction between these surface portions and in deflection of the first and second elements relative to one another, both in the sole and at the connecting portion and / or the edge of the shoe. The less flexible material of the insert having a higher elasticity than the sole may decrease contact between insert and ground due to the lower first coefficient of friction.

[0059] By providing the insert with two distinct surface portions which both have a first coefficient of friction being lower than the second coefficient of friction of the sole, a faster rate of force development may be resultant, whereby a more powerful take-off may be achieved.

[0060] At least a portion of the sideward facing surface portion of the at least one insert may form an acute angle relative to the edge of the shoe. The acute angle may enable the side of the shoe to easily slide parallel to the surface, so that even if a twist do occur, the energy transferred and thus the inversion torque is lowered sufficiently to avoid or reduce injury to the tissues.

[0061] The at least one insert may comprise a plurality of downward facing surface portions defining respective spaced-apart portions of the sole of the shoe. Thereby, a plurality of areas with adjacent first and second elements may be arranged in the sole to provide more sections which enable relative deflection during application of the force component in the first and second direction.

[0062] The shoe may comprise a plurality of inserts which may be identical in both size and shape. Alternatively, the inserts may be of different size and / or shape, e.g. dependent on their position relative to the sole.

[0063] In one embodiment, the plurality of inserts may be arranged along lateral side edge of the shoe. Each of the inserts of the plurality of inserts may comprise a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. In an alternative embodiment, none or only some of the insert may comprise a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. One or more of the inserts of the plurality of inserts may additionally or alternatively comprise a downward facing surface portion defining a portion of the sole of the shoe.

[0064] To facilitate positioning of the plurality of inserts relative to each other, at least some of the inserts may comprise a locking portion enabling locking of one insert to another insert. The locking portion may be a geometrical locking portion, where two inserts to be fixed relative to each other comprise a locking portion of matching shape. As an example, the locking portion of matching shape may be an indention in one insert and a corresponding protrusion in another insert. In another embodiment, the locking portions of matching shape may be an opening in one insert and a corresponding elevated part on another insert, where the inner shape of the opening matches the outer shape of the elevated part. The inner shape of the opening may as an example be disc-shaped, oval, triangular, square, etc. The application of a disc-shaped opening and a corresponding disc-shaped elevated part may provide the possibility of adjusting the angle between the inserts by turning the inserts relative to each other while still keeping them together.

[0065] At least one of the inserts may comprise two locking portions, such as an opening and an elevated part to thereby provide the possibility of attaching the insert to two adjacent inserts. The opening and the elevated part may be arranged at opposite ends of the insert to form a chain of inserts.

[0066] Whilst in certain embodiments of the invention, the selected portion, or part thereof, is provided by one or more structural entities attached to the remainder of the shoe, such as in particular its sole, the selected portion, or part thereof, may in other embodiments be releasably attached to the remainder of the shoe. Thereby, exchangeability of the selected portion may be achieved to meet various needs, or in case of wear.

[0067] The selected portion may comprise a layered structural entity providing the ability of an outmost layer to slide or deform relative to an inner layer to thereby promote the shoe's ability to slide relative to the ground.

[0068] In one embodiment, the at least one selected portion of the sole, the edge or the connecting portion is arranged at a tip portion of the shoe. A reduced friction in the tip portion of the shoe during application of the force component in the first direction may prevent or at least considerably reduce the risk of injuries due to early impact of the shoe in the front area resulting in a destabilised inversion before the rear part of the shoe engages ground.

[0069] Additionally, application of the force component in a backward direction, which occurs when the user is about to take a forward step, may enhance one of the first and second elements' contact with ground, i.e. increase one of the elements' contact surface area with the ground. In embodiments, in which that element, the contact surface area of which is increased, has a lower Young's modulus than the other element, initial compression in a direction perpendicular to ground of that element and subsequent expansion thereof as the shoe starts to push off from ground may assist in lifting the shoe off the ground. The amount of backward force applied to the ground and thus the amount of forward force imparted on the user's body may thereby be increased.

[0070] By reducing the braking force from the front and lateral edge of the shoe, and thanks to the provision of low friction properties, the risk of falling can be decreased. Such risk may be further reduced in direct collisions with objects by providing the show with an edge angle of less than 90 degrees. In one embodiment, the ground engaging surface of the sole displays low friction when the foot strike occurs with a high pressure in the anterior and lateral sole portions due to the presence of elements providing relatively low friction when the movement occurs in an inward direction. The desired traction limitation in the inward direction may be achieved by adjustment of the dimensions of the elements relative to each other. When a foot strike has an inappropriately high pressure and increased strike angle relative to the ground, the deformation of sole elements having comparatively higher surface friction will enable the lower friction elements to increasingly get in contact with the ground and enable a limitation in anterior and lateral plantar pressure. When the foot is striking the ground in a normal step, the plantar and lateral pressure is not high enough to deform the higher friction sole elements to an extent where the low friction elements will interact with the ground.

[0071] One benefit of embodiments of the invention may be the prevention of fall due to decreased braking forces, and the direction of the remaining force upwards over a potential object and lastly the limitation of inappropriate braking force in the anterior-lateral sole portion while full push-off traction may advantageously be preserved.

[0072] Abnormal gait patterns may be corrected due to increased pressure in the anterior-lateral regions by backwards pressure distribution, medially and more evenly, thereby improving the gait pattern and reducing the risk of pain and overuse injury.

[0073] Likewise, similar undesirable pressure can be distributed appropriately in other abnormal gait patterns. Also, this technique applies to alleviating unwanted pressure distribution in overuse injuries, pain conditions and ulcers.

[0074] With and outward directed force such as in the push off the higher friction elements may deflect in a direction that ensures they remain in contact with the ground and therefore preserves traction and prevents slipping.

[0075] The selected portion of the sole, the edge, or the connecting portion may generally comprise a resilient backing structure for biasing the shoe away from ground in a backward movement of the shoe. This may further facilitate lifting of the shoe.

[0076] The at least one selected portion of the sole, the edge or the connecting portion may be arranged at a lateral side edge of the shoe. This may lower the risk of lateral distortion considerably.

[0077] The shoe may comprise a gap or groove in an outwardly facing surface of the selected portion, wherein the gap or groove is disposed between the first and second elements. The gap or groove may facilitate deflection of the first and second elements relative to each other, as the gap or groove may provide less resistance to deflection of at least one of the first and second elements. In particular, the deflecting one of the first and second elements may deflect into the gap or groove.

[0078] This gap or groove along with other gaps and grooves may also increase the flexibility in one or more directions of the portion of the sole provided with the elements to thereby enhance the effects of the elements and differences in traction.

[0079] According to a second aspect, the invention provides a method of manufacturing a shoe according to any of the preceding claims, wherein: the first element is comprised in at least one insert secured to a portion of the sole of the shoe; the second element is integrated with the sole of the shoe; the sole of the shoe, except for the first element, and the second element are integrally from one and the same sole material; the method comprising the step of co-moulding or co-extruding the first element with the sole material.

[0080] The shoe may comprise a plurality of inserts, each of which comprises a locking portion for interlocking the insert with an adjacent insert, and wherein the method comprises interlocking the plurality of inserts prior to the step of co-moulding or co-extruding.

[0081] It should be understood that a skilled person would readily recognise that any feature described in combination with the first aspect of the invention could also be combined with the second aspect of the invention, and vice versa. The remarks set forth above in relation to the shoe are therefore equally applicable in relation to the method.Brief description of the drawings

[0082] Embodiments of the invention will now be further described with reference to the drawings, in which: Fig. 1 illustrates an embodiment of a shoe, Fig. 2 illustrates a part of an embodiment of a shoe, Figs. 3a-3c illustrate different views of an embodiment of an insert, Fig. 4 illustrates an embodiment of an insert, Figs. 5a-5b illustrate different views of an embodiment of an insert, Fig. 6 illustrates a plurality of inserts, Figs. 7a-7c illustrate different embodiments of an insert integrated in a sole, Figs. 8a-8c illustrate different views of an embodiment of an insert, Figs. 9a-9c illustrate different views of the insert illustrated in Figs. 8a-8c integrated in a sole, Figs. 10a and 10b illustrate an alternative embodiment of an insert, and Fig. 11 illustrates a further alternative embodiment of an insert. Detailed description of the drawings

[0083] It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0084] Fig. 1 illustrates an embodiment of a shoe 100 and Fig. 2 illustrates a part of the shoe 100 seen from below. The shoe 100 comprises a sole 102 with a ground-engaging surface 104 for engaging a ground (not shown), an edge 106, and a connecting portion 108 interconnecting and extending between the ground-engaging surface 104 the edge 108.

[0085] At least one selected portion of the sole 102, the edge 106, or the connecting portion 108 comprises two adjacent elements, a first element 110 having first material properties, and a second element 112 having second material properties. The two adjacent elements 110, 112 are disposed to enable deflection of the elements 110, 112 relative to one another when the selected portion is subjected to a force component parallel to the ground.

[0086] Furthermore, the adjacent elements 110, 112 are disposed, configured and deflectable relative to one another such that: application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and application of the force component to the selected portion in a second direction different the first direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the second coefficient of friction.

[0087] The first element 110 may be comprised in at least one insert 114 which may be secured to a portion of the sole 102 of the shoe 100. Figs. 3a-3c illustrate different views of an embodiment of an insert 114.

[0088] Figs. 3a and 3c are side views of the insert 114. In Fig. 3b, the insert 114 is shown from below.

[0089] The illustrated insert 114 forms two outwardly facing surfaces 116, one defining a portion of an outer surface of the sole, and one defining a portion of the edge of the shoe (not shown in Figs. 3a-3c).

[0090] Surface 116 provides a relatively low surface friction in order to achieve a different coefficient of friction between the selected portion and the ground depending on the direction of the force component. Conversely, the outer surface of the sole has a higher coefficient of friction, which enables the selected portion's grip relative to the ground being enhanced in circumstances where high friction properties are desired, and surface 116 enables a lower coefficient of friction in circumstances where low friction properties are desired. This allows for relative low friction in laterally directed movements. The decrease in inversion moment decreases the risk of e.g. ankle injury and the lesser translational force facilitates easier rotational movement and further decreased risk of anterior cruciate injury.

[0091] Insert 114 can also be used for pressure regulation to potentially reduce maximum pressure. By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against injury, maintain full performance and compensate disability.

[0092] The reduced maximum friction and pressure can tailor the preventive effect in e.g. anterior cruciate injuries as a result of the maximum moment around the foot being decreased. In certain areas of the shoe, it can, e.g., prevent fatigue fractures, overuse injuries and pressure ulcers.

[0093] Sole 116 can also compensate disability in dropfoot, clubfoot, cerebral paresis and other gait impairments by reducing abnormal pressures and directing these, e.g. medially and posteriorly to achieve better gait stability.

[0094] The insert 114 comprises a locking portion 118, 120 enabling locking the insert 114 to another insert. The locking portion 118, 120 is a geometrical locking portion matching shape. In the illustrated embodiment, the locking portion 120 is an opening in the insert 114, whereas the other locking portion is 118 is a corresponding elevated part, where the inner shape of the opening matches the outer shape of the elevated part.

[0095] The insert 114 comprise two locking portions 118, 120 arranged at opposite ends of the insert to enable forming a chain of inserts (see Fig. 6).

[0096] Fig. 4 illustrates an alternative embodiment of an insert 114. The insert 114 is similar to the insert illustrated in Fig. 3a-3c, with the exception that this insert 114 only forms one outwardly facing surface 116 defining a portion of the edge of the shoe.

[0097] Figs. 5a-5b illustrate different views of a further alternative of an embodiment of an insert 114. The insert 114 is similar to the insert illustrated in Fig. 3a-3c. The illustrated insert 114 forms two outwardly facing surfaces 116, one defining a portion of an outer surface of the sole, and one defining a portion of the edge of the shoe.

[0098] Compared to the insert illustrated in Figs. 3a-3c, the insert 114 illustrated in Figs. 5a-5b forms a triangular connecting portion 121 interconnecting the outwardly facing surfaces 116 and the locking portions 118, 120. The triangular shape of the connecting portion 121 results enhanced stiffness of the insert 114.

[0099] Fig. 6 illustrates a plurality of inserts 114 being connected to each other to thereby form a chain of inserts. The inserts 114 are connected to each other by use of a geometrical structure comprising locking portions 118, 120 of matching shape.

[0100] Figs. 7a-7c illustrate different embodiments of an insert 114 moulded into a sole 102 of a shoe. The second element 112 is integrated with the sole 102, whereby the second element 112 constitutes parts of the sole 102.

[0101] The sole 102 comprises one gap 122 and two gaps 122, respectively. The gaps are disposed between the first and second elements110, 112; i.e. between the insert 114 and the sole 102. The gaps 122 facilitate deflection of the first and second elements relative to each other, as the gaps 122 provide less resistance to deflection of at least one of the first and second elements

[0102] Figs. 8a-8c illustrate different views of an embodiment of an insert 214. Figs. 8a and 8b are side views of the insert 214. In Fig. 8c, the insert 214 is shown from below. The insert 214 is configured to be arranged at a tip portion of a shoe.

[0103] In Figs. 9a-9c the insert 214 illustrated in Figs. 8a-8c is integrated in a sole 202. The sole 202 comprises gaps 222 to facilitate deflection of the first and second elements relative to each other.

[0104] By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against trip by decreased maximum breaking force whilst still maintaining full push off performance and thereby decreasing risk of tripping while not increasing risk of slipping.

[0105] Along with portion 116, the sole can compensate disability in dropfoot, clubfoot, cerebral paresis and other gait impairments by reducing abnormal pressures and directing these, e.g., medially and posteriorly to achieve better gait stability.

[0106] Figs. 10a and 10b illustrate an alternative embodiment of an insert 214 for a shoe (not shown). As described above, at least one portion of the sole, the edge, or the connecting portion of the shoe comprises two adjacent elements, a first element which has first material properties, and a second element which has second material properties.

[0107] In Figs. 10a and 10b, the first element is comprised in a plurality of inserts 214 which are to be secured to a portion of the sole of the shoe. The inserts 214 form outwardly facing surfaces 216 which each defines a portion of an outer surface of the connecting portion and of the edge of the shoe.

[0108] In this embodiment, the second element (not shown) may be integrated with the sole of the shoe. As an example, the second element and the sole of the shoe are integrally formed from one and the same sole material. Thus, the second element may constitute a part / parts of the sole.

[0109] The inserts 214 are configured to be arranged at a tip portion of a shoe. An inwardly extending portion 225 extends transverse to the outwardly extending surface 216 and terminates in a free end 227. The inwardly extending portion 225 is configured to be integrated in a part of the sole (not shown). The width of the inwardly extending portion 225 tapers down from the outwardly extending surface 216 towards the free end 227 to facilitate positioning of a plurality of inserts 214 at the tip portion of a shoe.

[0110] It may be an advantage to arrange each of the inserts 214 at a distance to a neighbouring insert 214 to facilitated fastening of the inserts 214 in the sole of a shoe.

[0111] At the free end 227, the material thickness of the inwardly extending portion 225 is increased to provide a wedge-shaped part 229 at the free end 227. The wedge-shaped part 229 may further increase the fastening of the insert 214 to the shoe.

[0112] Fig. 11 illustrates a further alternative embodiment of an insert 314 in different side views and from below. In this embodiment, both the first element 310 and the second element 312 are comprised in the insert 314 which is to be secured to a portion of the sole of the shoe. The insert 314 forms outwardly facing surfaces 316 which each defines a portion of the sole of the shoe when integrated in a sole.

[0113] The first element 310 has first material properties, whereas the second element 312 has second material properties. As illustrated, the insert 314 comprises a plurality of first elements 310 and a single second element 312. The second element 312 forms a plurality of substantial elongated protrusions. A first element 310 extends along each of the protrusions, thereby forming a plurality of sets of first and second elements 310, 312 extending in a longitudinal direction. The sets of first and second elements 310, 312 are arranged at a distance to each other to provide a gap 322 between the sets of first and second elements 310, 312. The gaps 322 facilitate deflection of the first and second elements 310, 312.EXAMPLE 1

[0114] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0115] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D, BASF Chemical Company) with a siloxane polymer (such as Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0116] The raw material was dried for 45 minutes in 80° vacuum.

[0117] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 50 bar and 10 cm 3< / s injection speed. The back pressure was set to 20 bar at 4 s back pressure time. The nozzle temperature was set to be 215 °C, with the front, middle and back nozzle set to 205 °C, 205 °C and 205 °C, respectively. A cooling time of 8 s was provided.EXAMPLE 2

[0118] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0119] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0120] The raw material was dried for 45 minutes in 80° vacuum.

[0121] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 45 bar and 6 cm 3< / s injection speed. The back pressure was set to 45 bar at 5s back pressure time. The nozzle temperature was set to be 225 °C, with the front, middle and back nozzle set to 220 °C, 215 °C and 215 °C, respectively. A cooling time of 20 s was provided.EXAMPLE 3

[0122] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0123] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0124] The raw material was dried for 45 minutes in 80° vacuum.

[0125] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 35 bar and 20 cm 3< / s injection speed. The back pressure was set to 30 bar at 4s back pressure time. The nozzle temperature was set to be 230 °C, with the front, middle and back nozzle set to 225 °C, 220 °C and 220 °C, respectively. A cooling time of 30 s was provided.

Examples

example 1

[0114]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0115]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D, BASF Chemical Company) with a siloxane polymer (such as Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0116]The raw material was dried for 45 minutes in 80° vacuum.

[0117]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 50 bar and 10 cm 3< / s injection speed. The back pressure was set to 20 bar at 4 s back pressure time. The nozzle temperature was set to be 215 °C, with the front, middle and back nozzle set to 205 °C, 205 °C and 205 °C, respectively. A cooling time of 8 s was provided.

example 2

[0118]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0119]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0120]The raw material was dried for 45 minutes in 80° vacuum.

[0121]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 45 bar and 6 cm 3< / s injection speed. The back pressure was set to 45 bar at 5s back pressure time. The nozzle temperature was set to be 225 °C, with the front, middle and back nozzle set to 220 °C, 215 °C and 215 °C, respectively. A cooling time of 20 s was provided.

example 3

[0122]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0123]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0124]The raw material was dried for 45 minutes in 80° vacuum.

[0125]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 35 bar and 20 cm 3< / s injection speed. The back pressure was set to 30 bar at 4s back pressure time. The nozzle temperature was set to be 230 °C, with the front, middle and back nozzle set to 225 °C, 220 °C and 220 °C, respectively. A cooling time of 30 s was provided.

Field of the invention

[0001] The present invention generally relates to a shoe, such as a sport shoe, tailored to reduce the risk of injuries, compensate disability, and enhance performance. The invention also relates to a method of manufacturing a shoe.Background of the invention

[0002] It has been estimated that ankle injuries account for 15-30% of all injuries in sport.

[0003] An estimated 70-80% of athletes who suffer a sprain will have repeated problems. Functional ankle instability and sprains reoccur in about 10-60 % of athletes previously subject of acute injury. In these patients a part of the mechanism that causes re-injury is an erroneous sensation of the position of the ankle joint in plantar flexion 30° / inversion 20° whereby the joint can be more plantar-flexed and inverted when landing thus creating a risk of lateral distortion.

[0004] Ankle injuries typically occur when the ankle twists uncontrolled in an inversion / supination and possibly plantar flexion motion. This results in a lateral sprain (distortion) but fractures also occur frequently. The sprain causes damage to the calcaneofibular ligament and the talofibular anterior ligament in varying degrees and possibly the tibiofibular anterior ligament as well as the joint capsule and surrounding soft tissue.

[0005] The injuries can also be treated with taping or semi rigid braces but both methods have significant limitations as they provide a limited support especially for repeated injuries and often degrades freedom of movement for the wearer. Also, the restricting effect of tape is lost after varying periods of exercise (Am J Sports Med November 2010 vol. 38 no. 11 2194-2200).

[0006] From a shoe design point of view, prevention of sports injuries has hitherto generally focussed on stability increase of shoes, enhancement of foot support, as well as on improvement of anti-slip properties of shoes. Despite past efforts, it has however been found that a need remains for further development of a shoe which contributes to reducing the occurrence of sports injuries, notably ankle and knee injuries.

[0007] International patent publication No. WO 2016 / 207381 discloses a shoe having an area of reduced friction with a view to reducing the ability of the user's foot to rotate relative to ground (inversion and internal rotation) when the load of the user's body is shifted towards or lands near an edge of the shoe. Whilst the invention of WO 2016 / 207381 constitutes an improvement over the state of the art at the time the invention was made, a further need for improvement has arisen.

[0008] Secondly, the invention is developed to prevent falls, which globally are a major public health problem for people with various gait impairments (disabilities, diseases, age, pressure related pain, overuse injuries) and often has many consequences for both the individual and the public. The personal consequences can be fractures which results in long recoveries, and a worsening of life quality. In some cases, a fall can even result in fatality due to head trauma or long recoveries. Besides the personal consequences, treatment of a fall has high costs for society and the healthcare system.

[0009] Falls often occur due to tripping, which is characterized by unanticipated increased braking force in the anterior region of the shoe and sole. This typically happens when taking a short step or hitting the ground with the tip of the shoe when correcting your walk as a result of a disruption. The resulting brake force results in overbalance. If the brake force reaches a certain threshold, there is no longer a possibility for regaining control over your balance, which will result in a fall.

[0010] In some gait impairments a plantar flexion and inverted foot position is seen, which results in an anterior and lateral pressure distribution during foot strike. This gait pattern will, besides the increased risk of falling, also cause pain in the foot due to the high plantar pressure.Description of the invention

[0011] It is an object of embodiments of the invention to provide an improved shoe, such as improved sports shoe. It is in particular an object of embodiments of the invention to provide a shoe which enhances its grip relative to the ground in circumstances when a solid grip is desired, and which enhances slip relative to the ground in circumstances when low friction properties relative to the ground are desired.

[0012] According to a first aspect, the invention provides a shoe comprising:. a sole with a ground-engaging surface for engaging the ground; an edge; and a connecting portion interconnecting and extending between the ground-engaging surface and the edge; wherein: at least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first one which has first material properties, and a second one of which has second material properties, the two adjacent elements being disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground, commonly referred to as a "horizontal force"; and the adjacent elements are disposed, configured and deflectable relative to one another such that: application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and application of the force component to the selected portion in a second direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the second coefficient of friction.

[0013] In the present context, injuries should be understood to include, but not be limited to sprains, including syndesmosis ruptures, dislocations, strains, and fractures. Injuries could also be understood to include osteochondral lesions. In the context of falling prevention various trauma might result such as contusions, fractures and concussion or haemorrhage. In the context of overuse injuries these are fasciitis, tendinitis, tendinopathies, bursitis, and stress fractures. Pressure related injuries and disability includes diabetic and other ulcers, osteoarthritis pain from foot, knee and hip and pain due to pes planus, overpronation and similar conditions.

[0014] In the present context, the ground-engaging surface should be understood to be that part of the shoe which engages the ground when the wearer of the shoe is standing up straight and puts equal weight on both feet. The ground-engaging surface may differ from the part of the shoe that engages the ground during movement of the wearer such as jumping, landing, turning, etc.

[0015] In the present context, the edge is to be understood as extending from the connecting portion in a direction away from the ground-engaging surface and the connecting portion, the edge extending in a direction transverse, i.e. not parallel, to the ground-engaging surface.

[0016] At least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first element which has first material properties, and a second element which has second material properties. The first and second material properties may in particular include at least one of surface friction properties and Young's Modulus. Differences in surface friction properties may be achieved by differences in geometries, such as differences in surface roughness, or through selection of different materials or different material compositions for the elements. The two adjacent elements are disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground, i.e. a horizontal force. Thus, the two adjacent elements may be arranged in contact with each other or alternatively adjacent to each other without contact, whereby subjection of a force component parallel to the ground to the selected portion; i.e. to at least one of the elements, will result in deflection of the elements relative to one another. By deflection of the elements relative to each other at least one of the elements is deflected.

[0017] Due to the ability of the first and second elements to deflect relative to each other, the force component may decrease or increase the extent of each of the elements' contact surface area with the ground, depending on the direction of the force component. The differences between the first and second material properties, such as in particular, for example, different friction properties, thereby confer different coefficients of friction between the selected portion and the ground, depending on the extent of the elements' overlap with the ground, which in turn depends on the direction of the force component. It may thus be achieved that the selected portion's grip relative to ground is enhanced in circumstances when a solid grip is desired, and that the selected portion's slip properties relative to ground, i.e. the selected portion's ability to slide relative to ground, increase in circumstances when low friction properties are desired.

[0018] In particular, on the one hand, low friction properties of the selected portion may be desired with a view to enable the shoe to slide parallel to its underlying surface during a shift of the user's weight outwardly or forwardly when no realignment of the user's body can be achieved, i.e. when a force component in a lateral or forward direction is applied. The amount of energy transferred to user's foot and leg anatomy and further up the kinetic chain, resulting from the shoe's ground grip may thus be reduced. In some incidents, the user may fall due to loss of grips, but the risk of general injury, however, reduces relative to the risk that would have existed if the selected portion of the shoe had maintained its grip relative to ground. In these cases, loss of grip may also enhance performance in some athletic shoes used for handball, football, floorball or dance as it allows the user to go into the splits with minimum force to overcome in an element is applied to the heel portion of the shoe.

[0019] On the other hand, high friction properties of the selected portion may be desired with a view to enabling a firm grip between the shoe and ground when the user's body is in balance, such as when the user pushes off for a jump or a step. Under such circumstances the direction of the force component to the selected portion is different from the force component applied when the user is out of balance. In particular, when pushing off for a jump or a step or when striving for realignment, the force component is generally inwardly directed towards the centre of pressure on the shoes. Under such circumstances, the shoe's grip relative to ground should generally be firm, i.e. a relative high coefficient of friction is desirable in order to ensure stability and balance compared to the relatively low coefficient of friction which is desirable when the force component is in an outward direction away from the foot's centre of pressure. It should be understood that the first and second elements may be embodied as a single structural entity, the properties of which depend upon the direction of a force component applied to such single structural entity. For example, flexible, deformable and / or movable protrusions may be provided to an outer surface portion of such entity, whereby a protrusion distance (or height) and / or an angle of such protrusions relative to an underlying support surface may vary with the direction and / or magnitude of an applied force, which thereby control frictional properties of the selected portion of the shoe.

[0020] In one embodiment, an air gap is arranged between the first and second element. In an alternative embodiment, an air gap may be arranged between a part of the first and second element which may also be in contact with each. In a further alternative embodiment, the first and second elements may be in contact with each other along their abutting surfaces.

[0021] The adjacent elements are disposed, configured and deflectable relative to one another such that application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and such that application of the force component to the selected portion in a second direction being different from the first direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the first coefficient of friction.

[0022] Consequently, it may be achieved that friction is reduced when the selected portion is subjected to the force component in the first direction and that friction is not reduced when the selection portion is subjected to the force component in the second direction, where the first coefficient of friction is lower than the second coefficient of friction. It should be understood, that the opposite case may also be applicable, so that friction is reduced when the selected portion is subjected to the force component in the second direction; i.e. when the second coefficient of friction is lower than the first coefficient of friction. Thus, the use of the terms first direction and second direction are not limiting, and can be oppositely applied.

[0023] The first element and the second element are disposed to enable deflection of the first and second element relative to each other. The first and second elements may be arranged relative to each other so that application of a force component in the first direction increases contact between the first element and ground and may reduce contact between the second element and ground, whereby the first coefficient of friction may be the dominant friction. On the contrary may application of a force component in the second direction increase contact between the second element and ground and may reduce contact between the first element and ground, whereby the second coefficient of friction may be the dominant friction.

[0024] When the first coefficient of friction is lower than the second coefficient of friction, friction between the selected portion and ground is lower when the selected portion is subjected to the force component in the first direction than friction between the selected portion and ground when the selection portion is subjected to the force component in the second direction.

[0025] The reduction of friction may prevent ankle sprains as most sprains happen with the foot in contact with the ground during landing or other movements at which the foot interacts with ground in an unpredicted or unbalanced manner, such as when the foot lands on an opponent's foot or positions itself incorrectly relative to ground. Moreover, the selected portion when reducing friction may ensure increased mobility of the shoe when the area of reduced friction is in contact with the ground thus preventing the shoe from remaining at an undesirable position relative to ground. Instead, the shoe is enabled to slide parallel to its underlying surface or reducing undesirable translational and rotational forces such as in- / eversion of the foot, in / external rotation with sprain risk due to harmful subsequent transferral of kinetic energy to the kinetic chain and surrounding tissues and decreased sports performance due to suboptimal positioning for muscle force generation. Also, unwanted braking force on the edge of the shoe will affect performance negatively, e.g. in turning and sideways movement. Such adverse effects are diminished by the lowered friction in the direction of the shoe movement. Accordingly, the effect will increase sliding in, e.g., tennis and enhance safety of this movement in tennis.

[0026] The elements can also be used for pressure regulation to potentially reduce maximum pressure. By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against injury, maintain full performance and compensate disability. In the context of a sideways directed translational and rotational forces this will have a preventive effect on knee sprains.

[0027] Deflection of the first and second element relative to each other may be achieved by forming the first element of a first material being less flexible and / or having a higher elasticity than a second material of which the second element is formed. Additionally, or alternatively, the first material may have a lower surface friction when the force component is in the first direction. As mentioned above, this first and second material may be oppositely selected.

[0028] The first material properties may thus comprise at least one of a Young's modulus and a first surface friction, and the second material properties may comprise at least one of a second Young's modulus and a second surface friction.

[0029] It should be understood, that the first element and / or the second element may be formed of a plurality of materials, where first and second material properties are the resulting material properties for each respective one of the first and second elements.

[0030] Thus, in one embodiment, the first of at least one selected portion of the sole, the edge or the connecting portion having first material properties comprises a first material and the second of at least one selected portion of the sole, the edge or the connection portion having second material properties comprises a second material, wherein the first material comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA), polyethylene such as ultra-high-molecular-weight polyethylene (UHMW-PE), synthetic rubbers, such as styrene-butadiene rubber (SBR), Styrene Butadiene Styrene, nylon or mixtures thereof with a Shore D hardness 40 or higher, and wherein the first material further comprises an additional material selected from the list comprising polymerized polysiloxanes such as polymerized silicone, polyethylene such as ultra-high molecular (UHMW) siloxane polymer, per- and polyfluoroalkyls (PFAS) such as polytetrafluoroethylene (PTFE), graphene, graphite or mixtures thereof.

[0031] The second material comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA)" or mixtures thereof with a Shore A hardness 50-85.

[0032] The second material is typically selected from any conventional shoe sole material. The method of measurement of Shore hardness measures the depth of indentation in the material created by a given force on a standardized presser foot. Shore A hardness is typically measured by an indenting foot having a hardened steel rod having 1.1 mm-1.4 mm diameter, with a truncated 35° cone and 0.79 mm diameter. The applied mass is typically 0.822 kg, which results in a force (N) of 8.064.

[0033] Shore hardness D is typically measured by an indenting foot having a hardened steel rod having 1.1 mm-1.4 mm diameter, with a truncated 30° conical point and 0.1 mm radius tip. The applied mass is typically 4.550 kg, which results in a force (N) of 44.64.

[0034] As it is understood by the skilled person, a material having a Shore Hardness A 50-85 is considered to be a softer material than a material having a Shore Hardness D 40 or higher.

[0035] The first material is considered to be low friction in comparison to the second material, which, in the context of the present invention is considered to be a high friction material.

[0036] According to the invention, it is possible to provide a first material, such as TPU having a Shore Hardness D 40 or higher in combination with polymerized siloxanes, such as polymerised silicone. However, it is also possible to provide a first material, such as TPU having a Shore Hardness D 40 or higher in combination with graphene and / or PTFE to provide the low friction material. Accordingly, a first material may be provided such that silicone is absent and only e.g., PTFE and / or graphene is present.

[0037] Due to the first and second material having different friction coefficients, a multi-frictional composition is provided. The multi-frictional composition typically comprises a first material having first friction properties and a second material having second friction properties. Preferably, the first material has a friction coefficient less than 0.7 as measured in shoe friction test (ISO 13287:2012). The second material has high friction with a friction coefficient of more than 0.7 as measured in shoe friction test (ISO 13287:2012).

[0038] The first material has a Shore D hardness of 40 or more as defined by ASTM 2240. An example of such suitable first material is Elastollan ®< 1174D (BASF Chemical Company), which has a Shore D hardness of 74.

[0039] The weight% of the additional material is between about 5-30% based on the total weight of the first material, preferably about 15-25%, more preferably about 20-22% and most preferably about 20% based on the total weight of the first material.

[0040] An example of an additional material is MB 50-017 Masterbatch (Dow Corning ®< ) which comprises 50% of ultra-high-molecular-weight (UHMW) siloxane polymer dispersed in thermoplastic polyurethane (TPU) but other suitable commercially available materials may also be used.

[0041] In some embodiments, the composition comprises e.g., TPU having Shore hardness D 40 or higher and e.g., UHMW siloxane polymer.

[0042] The second material and the sole of the shoe are integrally formed from one and the same sole material. The first material may have a lower surface friction than the second material when the force component is in the second direction.

[0043] The elements may be configured such that a surface friction of the selected portion is dependent on the height of the elements relative to each other. In particular, one of the elements may deflect more than the other one when subjected to pressure to thereby render the surface friction of the selection portion dependent from the amount of pressure applied.

[0044] In one embodiment, each of the first and second elements may define outwardly facing surfaces, each of which defines a portion of an outer surface of the sole, the connecting portion and / or the edge of the shoe. The first element may have a Young's modulus of a first value and a first surface roughness and / or a first coefficient of friction on its outwardly facing surface, and the second element may have a Young's modulus of a second value and a second surface roughness and / or a second coefficient of friction on its outwardly facing surface; where the value of the first Young's modulus is higher than the value of the second Young's modulus, and the first surface roughness is lower than the second surface roughness. In this embodiment, the friction is reduced when the selected portion is subjected to the force component in the first direction and friction is not reduced when the selection portion is subjected to the force component in the second direction.

[0045] As mentioned above, the value of the first Young's modulus may be lower than the value of the second Young's modulus, and the first surface roughness and / or the first coefficient of friction may be higher than the second surface roughness and / or the second coefficient of friction, respectively, in an alternative embodiment.

[0046] As an example, the first element may define one or more outwardly facing surfaces of the connecting portion and the edge of the shoe, whereas the second element may define one or more outwardly facing surfaces of an outer surface of the sole and the connecting portion. In an alternative example, both the first element and the second element may define one or more outwardly facing surfaces of an outer surface of the sole and of the connecting portion and of the edge of the shoe.

[0047] It should be understood, that other combinations may be applicable in other embodiments, where each of the first and second elements may define outwardly facing surfaces, each of which defines a portion of an outer surface of the sole and / or the connecting portion and / or the edge of the shoe.

[0048] In the present context, a sports shoe may be understood as a shoe suitable for wear when engaging in various forms of indoor and / or outdoor sports activities such as football, basketball, volleyball, handball, floorball, tennis, badminton, dancing, table tennis, fitness, etc. Such shoe may also be referred to as an athletic shoe.

[0049] In the context of the present invention, the shoe may also be a safety shoe, a casual shoe or an orthopaedic shoe.

[0050] The shoe may define a foot part and a leg part, wherein the leg part extends no longer than a distance equal to one third of the distance from a wearer's knee to the farthest end of the wearer's heel. In this case, the shoe may be particularly suitable for use as a sports shoe because it may allow sufficient limb mobility for the wearer of the shoe to perform sports. In the present context, the foot part is to be understood as the part of the shoe encompassing the wearer's foot. The leg part is to be understood as the part of the shoe vertically extending between the surface of the wearer's heel furthest from the wearer's knee and the part of the shoe closest to the wearer's knee. As such, the foot part and the leg part of the shoe overlap.

[0051] The shoe may define a foot part and a leg part, wherein the leg part extends no longer than 1.25 times the longest straight-line extend of a wearer's foot. Thus, the height of the leg part is thus at most equal to 1.25 times the length of the foot part, or at most equal to the length of the foot part, or smaller than then length of the foot part. The height of the leg part is preferably measured as a straight-line distance from the bottom of the sole of the shoe to an uppermost edge of the shoe for circumferentially surrounding the wearer's leg. In such embodiments, the shoe may be particularly suitable for use as a sports shoe because it may allow sufficient limb mobility for the wearer of the shoe to perform sports. In present context, the foot part is to be understood as the part of the shoe encompassing the wearer's foot. The leg part is to be understood as the part of the shoe vertically extending between the surface of the wearer's heel furthest from the wearer's knee and the part of the shoe closest to the wearer's knee. As such, the foot part and the leg part of the shoe overlap. The longest straight-line extend of the wearer's foot is commonly equal to the distance between the furthest ends of the wearer's toes and heel parallel to ground when the wearer is standing up.

[0052] The selected portion may be flush with the surrounding areas of the shoe. In other words, selected portion may be arranged to not protrude from the surrounding areas of the shoe. In this case, the shape of the shoe may be essentially similar to the shape the shoe would have, if the shoe did not comprise the selected portion.

[0053] In embodiments of the present invention, the outwardly facing surface of the first element preferably defines a first coefficient of friction of less than 0.7 as tested according to ISO 13287:2012 by providing a forepart of a sole of a test shoe as according to ISO 13287:2012 with the first material properties and using the backward slip on the forepart test without lubricant as according to ISO 13287:2012. The outwardly facing surface of the second element preferably defines a second coefficient of friction of more than 0.7 as tested according to ISO 13287:2012 by providing a forepart of a sole of a test shoe as according to ISO 13287:2012 with the second material properties and using the backward slip on the forepart test without lubricant as according to ISO 13287:2012.

[0054] It should be understood that the first coefficient of friction may be different for different parts of outwardly facing surface of the first element and the second element, respectively. The friction coefficient may gradually change within the outwardly facing surface(s). The different first coefficients of friction and / or second coefficients of friction may be provided by a plurality of materials and / or varying surface frictions of the first and / or second element.

[0055] The first element may be comprised in at least one insert secured to a portion of the sole of the shoe. The at least one insert may form one or more outwardly facing surfaces which may each define a portion of an outer surface of the sole, and / or of the connecting portion and / or of the edge of the shoe.

[0056] The second element may be integrated with the sole of the shoe. In one embodiment, the second element and the sole of the shoe, except for the first element, are integrally formed from one and the same sole material. Thus, the second element may constitute a part / parts of the sole.

[0057] With a view to securing a durable mechanical structure of the selected portion, the at least one insert may be co-moulded with the sole material. This may be achieved by moulding the sole material onto the at least one insert. This may be especially applicable when using a sole material having a lower Young's modulus than the material of the at least one insert.

[0058] In one embodiment, the at least one insert may comprise a downward facing surface portion defining a portion of the sole of the shoe and a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. Consequently, the application of the force component in a first direction may result in a lower coefficient of friction between these surface portions and in deflection of the first and second elements relative to one another, both in the sole and at the connecting portion and / or the edge of the shoe. The less flexible material of the insert having a higher elasticity than the sole may decrease contact between insert and ground due to the lower first coefficient of friction.

[0059] By providing the insert with two distinct surface portions which both have a first coefficient of friction being lower than the second coefficient of friction of the sole, a faster rate of force development may be resultant, whereby a more powerful take-off may be achieved.

[0060] At least a portion of the sideward facing surface portion of the at least one insert may form an acute angle relative to the edge of the shoe. The acute angle may enable the side of the shoe to easily slide parallel to the surface, so that even if a twist do occur, the energy transferred and thus the inversion torque is lowered sufficiently to avoid or reduce injury to the tissues.

[0061] The at least one insert may comprise a plurality of downward facing surface portions defining respective spaced-apart portions of the sole of the shoe. Thereby, a plurality of areas with adjacent first and second elements may be arranged in the sole to provide more sections which enable relative deflection during application of the force component in the first and second direction.

[0062] The shoe may comprise a plurality of inserts which may be identical in both size and shape. Alternatively, the inserts may be of different size and / or shape, e.g. dependent on their position relative to the sole.

[0063] In one embodiment, the plurality of inserts may be arranged along lateral side edge of the shoe. Each of the inserts of the plurality of inserts may comprise a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. In an alternative embodiment, none or only some of the insert may comprise a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe. One or more of the inserts of the plurality of inserts may additionally or alternatively comprise a downward facing surface portion defining a portion of the sole of the shoe.

[0064] To facilitate positioning of the plurality of inserts relative to each other, at least some of the inserts may comprise a locking portion enabling locking of one insert to another insert. The locking portion may be a geometrical locking portion, where two inserts to be fixed relative to each other comprise a locking portion of matching shape. As an example, the locking portion of matching shape may be an indention in one insert and a corresponding protrusion in another insert. In another embodiment, the locking portions of matching shape may be an opening in one insert and a corresponding elevated part on another insert, where the inner shape of the opening matches the outer shape of the elevated part. The inner shape of the opening may as an example be disc-shaped, oval, triangular, square, etc. The application of a disc-shaped opening and a corresponding disc-shaped elevated part may provide the possibility of adjusting the angle between the inserts by turning the inserts relative to each other while still keeping them together.

[0065] At least one of the inserts may comprise two locking portions, such as an opening and an elevated part to thereby provide the possibility of attaching the insert to two adjacent inserts. The opening and the elevated part may be arranged at opposite ends of the insert to form a chain of inserts.

[0066] Whilst in certain embodiments of the invention, the selected portion, or part thereof, is provided by one or more structural entities attached to the remainder of the shoe, such as in particular its sole, the selected portion, or part thereof, may in other embodiments be releasably attached to the remainder of the shoe. Thereby, exchangeability of the selected portion may be achieved to meet various needs, or in case of wear.

[0067] The selected portion may comprise a layered structural entity providing the ability of an outmost layer to slide or deform relative to an inner layer to thereby promote the shoe's ability to slide relative to the ground.

[0068] In one embodiment, the at least one selected portion of the sole, the edge or the connecting portion is arranged at a tip portion of the shoe. A reduced friction in the tip portion of the shoe during application of the force component in the first direction may prevent or at least considerably reduce the risk of injuries due to early impact of the shoe in the front area resulting in a destabilised inversion before the rear part of the shoe engages ground.

[0069] Additionally, application of the force component in a backward direction, which occurs when the user is about to take a forward step, may enhance one of the first and second elements' contact with ground, i.e. increase one of the elements' contact surface area with the ground. In embodiments, in which that element, the contact surface area of which is increased, has a lower Young's modulus than the other element, initial compression in a direction perpendicular to ground of that element and subsequent expansion thereof as the shoe starts to push off from ground may assist in lifting the shoe off the ground. The amount of backward force applied to the ground and thus the amount of forward force imparted on the user's body may thereby be increased.

[0070] By reducing the braking force from the front and lateral edge of the shoe, and thanks to the provision of low friction properties, the risk of falling can be decreased. Such risk may be further reduced in direct collisions with objects by providing the show with an edge angle of less than 90 degrees. In one embodiment, the ground engaging surface of the sole displays low friction when the foot strike occurs with a high pressure in the anterior and lateral sole portions due to the presence of elements providing relatively low friction when the movement occurs in an inward direction. The desired traction limitation in the inward direction may be achieved by adjustment of the dimensions of the elements relative to each other. When a foot strike has an inappropriately high pressure and increased strike angle relative to the ground, the deformation of sole elements having comparatively higher surface friction will enable the lower friction elements to increasingly get in contact with the ground and enable a limitation in anterior and lateral plantar pressure. When the foot is striking the ground in a normal step, the plantar and lateral pressure is not high enough to deform the higher friction sole elements to an extent where the low friction elements will interact with the ground.

[0071] One benefit of embodiments of the invention may be the prevention of fall due to decreased braking forces, and the direction of the remaining force upwards over a potential object and lastly the limitation of inappropriate braking force in the anterior-lateral sole portion while full push-off traction may advantageously be preserved.

[0072] Abnormal gait patterns may be corrected due to increased pressure in the anterior-lateral regions by backwards pressure distribution, medially and more evenly, thereby improving the gait pattern and reducing the risk of pain and overuse injury.

[0073] Likewise, similar undesirable pressure can be distributed appropriately in other abnormal gait patterns. Also, this technique applies to alleviating unwanted pressure distribution in overuse injuries, pain conditions and ulcers.

[0074] With and outward directed force such as in the push off the higher friction elements may deflect in a direction that ensures they remain in contact with the ground and therefore preserves traction and prevents slipping.

[0075] The selected portion of the sole, the edge, or the connecting portion may generally comprise a resilient backing structure for biasing the shoe away from ground in a backward movement of the shoe. This may further facilitate lifting of the shoe.

[0076] The at least one selected portion of the sole, the edge or the connecting portion may be arranged at a lateral side edge of the shoe. This may lower the risk of lateral distortion considerably.

[0077] The shoe may comprise a gap or groove in an outwardly facing surface of the selected portion, wherein the gap or groove is disposed between the first and second elements. The gap or groove may facilitate deflection of the first and second elements relative to each other, as the gap or groove may provide less resistance to deflection of at least one of the first and second elements. In particular, the deflecting one of the first and second elements may deflect into the gap or groove.

[0078] This gap or groove along with other gaps and grooves may also increase the flexibility in one or more directions of the portion of the sole provided with the elements to thereby enhance the effects of the elements and differences in traction.

[0079] According to a second aspect, the invention provides a method of manufacturing a shoe according to any of the preceding claims, wherein: the first element is comprised in at least one insert secured to a portion of the sole of the shoe; the second element is integrated with the sole of the shoe; the sole of the shoe, except for the first element, and the second element are integrally from one and the same sole material; the method comprising the step of co-moulding or co-extruding the first element with the sole material.

[0080] The shoe may comprise a plurality of inserts, each of which comprises a locking portion for interlocking the insert with an adjacent insert, and wherein the method comprises interlocking the plurality of inserts prior to the step of co-moulding or co-extruding.

[0081] It should be understood that a skilled person would readily recognise that any feature described in combination with the first aspect of the invention could also be combined with the second aspect of the invention, and vice versa. The remarks set forth above in relation to the shoe are therefore equally applicable in relation to the method.Brief description of the drawings

[0082] Embodiments of the invention will now be further described with reference to the drawings, in which: Fig. 1 illustrates an embodiment of a shoe, Fig. 2 illustrates a part of an embodiment of a shoe, Figs. 3a-3c illustrate different views of an embodiment of an insert, Fig. 4 illustrates an embodiment of an insert, Figs. 5a-5b illustrate different views of an embodiment of an insert, Fig. 6 illustrates a plurality of inserts, Figs. 7a-7c illustrate different embodiments of an insert integrated in a sole, Figs. 8a-8c illustrate different views of an embodiment of an insert, Figs. 9a-9c illustrate different views of the insert illustrated in Figs. 8a-8c integrated in a sole, Figs. 10a and 10b illustrate an alternative embodiment of an insert, and Fig. 11 illustrates a further alternative embodiment of an insert. Detailed description of the drawings

[0083] It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0084] Fig. 1 illustrates an embodiment of a shoe 100 and Fig. 2 illustrates a part of the shoe 100 seen from below. The shoe 100 comprises a sole 102 with a ground-engaging surface 104 for engaging a ground (not shown), an edge 106, and a connecting portion 108 interconnecting and extending between the ground-engaging surface 104 the edge 108.

[0085] At least one selected portion of the sole 102, the edge 106, or the connecting portion 108 comprises two adjacent elements, a first element 110 having first material properties, and a second element 112 having second material properties. The two adjacent elements 110, 112 are disposed to enable deflection of the elements 110, 112 relative to one another when the selected portion is subjected to a force component parallel to the ground.

[0086] Furthermore, the adjacent elements 110, 112 are disposed, configured and deflectable relative to one another such that: application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and application of the force component to the selected portion in a second direction different the first direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the second coefficient of friction.

[0087] The first element 110 may be comprised in at least one insert 114 which may be secured to a portion of the sole 102 of the shoe 100. Figs. 3a-3c illustrate different views of an embodiment of an insert 114.

[0088] Figs. 3a and 3c are side views of the insert 114. In Fig. 3b, the insert 114 is shown from below.

[0089] The illustrated insert 114 forms two outwardly facing surfaces 116, one defining a portion of an outer surface of the sole, and one defining a portion of the edge of the shoe (not shown in Figs. 3a-3c).

[0090] Surface 116 provides a relatively low surface friction in order to achieve a different coefficient of friction between the selected portion and the ground depending on the direction of the force component. Conversely, the outer surface of the sole has a higher coefficient of friction, which enables the selected portion's grip relative to the ground being enhanced in circumstances where high friction properties are desired, and surface 116 enables a lower coefficient of friction in circumstances where low friction properties are desired. This allows for relative low friction in laterally directed movements. The decrease in inversion moment decreases the risk of e.g. ankle injury and the lesser translational force facilitates easier rotational movement and further decreased risk of anterior cruciate injury.

[0091] Insert 114 can also be used for pressure regulation to potentially reduce maximum pressure. By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against injury, maintain full performance and compensate disability.

[0092] The reduced maximum friction and pressure can tailor the preventive effect in e.g. anterior cruciate injuries as a result of the maximum moment around the foot being decreased. In certain areas of the shoe, it can, e.g., prevent fatigue fractures, overuse injuries and pressure ulcers.

[0093] Sole 116 can also compensate disability in dropfoot, clubfoot, cerebral paresis and other gait impairments by reducing abnormal pressures and directing these, e.g. medially and posteriorly to achieve better gait stability.

[0094] The insert 114 comprises a locking portion 118, 120 enabling locking the insert 114 to another insert. The locking portion 118, 120 is a geometrical locking portion matching shape. In the illustrated embodiment, the locking portion 120 is an opening in the insert 114, whereas the other locking portion is 118 is a corresponding elevated part, where the inner shape of the opening matches the outer shape of the elevated part.

[0095] The insert 114 comprise two locking portions 118, 120 arranged at opposite ends of the insert to enable forming a chain of inserts (see Fig. 6).

[0096] Fig. 4 illustrates an alternative embodiment of an insert 114. The insert 114 is similar to the insert illustrated in Fig. 3a-3c, with the exception that this insert 114 only forms one outwardly facing surface 116 defining a portion of the edge of the shoe.

[0097] Figs. 5a-5b illustrate different views of a further alternative of an embodiment of an insert 114. The insert 114 is similar to the insert illustrated in Fig. 3a-3c. The illustrated insert 114 forms two outwardly facing surfaces 116, one defining a portion of an outer surface of the sole, and one defining a portion of the edge of the shoe.

[0098] Compared to the insert illustrated in Figs. 3a-3c, the insert 114 illustrated in Figs. 5a-5b forms a triangular connecting portion 121 interconnecting the outwardly facing surfaces 116 and the locking portions 118, 120. The triangular shape of the connecting portion 121 results enhanced stiffness of the insert 114.

[0099] Fig. 6 illustrates a plurality of inserts 114 being connected to each other to thereby form a chain of inserts. The inserts 114 are connected to each other by use of a geometrical structure comprising locking portions 118, 120 of matching shape.

[0100] Figs. 7a-7c illustrate different embodiments of an insert 114 moulded into a sole 102 of a shoe. The second element 112 is integrated with the sole 102, whereby the second element 112 constitutes parts of the sole 102.

[0101] The sole 102 comprises one gap 122 and two gaps 122, respectively. The gaps are disposed between the first and second elements110, 112; i.e. between the insert 114 and the sole 102. The gaps 122 facilitate deflection of the first and second elements relative to each other, as the gaps 122 provide less resistance to deflection of at least one of the first and second elements

[0102] Figs. 8a-8c illustrate different views of an embodiment of an insert 214. Figs. 8a and 8b are side views of the insert 214. In Fig. 8c, the insert 214 is shown from below. The insert 214 is configured to be arranged at a tip portion of a shoe.

[0103] In Figs. 9a-9c the insert 214 illustrated in Figs. 8a-8c is integrated in a sole 202. The sole 202 comprises gaps 222 to facilitate deflection of the first and second elements relative to each other.

[0104] By adjusting the height of the element and sole material relative to each other, a certain controlled force necessary to elicit difference in friction can be achieved. This force that elicits lower friction in one direction can also be varied according to the desired effect in order to protect against trip by decreased maximum breaking force whilst still maintaining full push off performance and thereby decreasing risk of tripping while not increasing risk of slipping.

[0105] Along with portion 116, the sole can compensate disability in dropfoot, clubfoot, cerebral paresis and other gait impairments by reducing abnormal pressures and directing these, e.g., medially and posteriorly to achieve better gait stability.

[0106] Figs. 10a and 10b illustrate an alternative embodiment of an insert 214 for a shoe (not shown). As described above, at least one portion of the sole, the edge, or the connecting portion of the shoe comprises two adjacent elements, a first element which has first material properties, and a second element which has second material properties.

[0107] In Figs. 10a and 10b, the first element is comprised in a plurality of inserts 214 which are to be secured to a portion of the sole of the shoe. The inserts 214 form outwardly facing surfaces 216 which each defines a portion of an outer surface of the connecting portion and of the edge of the shoe.

[0108] In this embodiment, the second element (not shown) may be integrated with the sole of the shoe. As an example, the second element and the sole of the shoe are integrally formed from one and the same sole material. Thus, the second element may constitute a part / parts of the sole.

[0109] The inserts 214 are configured to be arranged at a tip portion of a shoe. An inwardly extending portion 225 extends transverse to the outwardly extending surface 216 and terminates in a free end 227. The inwardly extending portion 225 is configured to be integrated in a part of the sole (not shown). The width of the inwardly extending portion 225 tapers down from the outwardly extending surface 216 towards the free end 227 to facilitate positioning of a plurality of inserts 214 at the tip portion of a shoe.

[0110] It may be an advantage to arrange each of the inserts 214 at a distance to a neighbouring insert 214 to facilitated fastening of the inserts 214 in the sole of a shoe.

[0111] At the free end 227, the material thickness of the inwardly extending portion 225 is increased to provide a wedge-shaped part 229 at the free end 227. The wedge-shaped part 229 may further increase the fastening of the insert 214 to the shoe.

[0112] Fig. 11 illustrates a further alternative embodiment of an insert 314 in different side views and from below. In this embodiment, both the first element 310 and the second element 312 are comprised in the insert 314 which is to be secured to a portion of the sole of the shoe. The insert 314 forms outwardly facing surfaces 316 which each defines a portion of the sole of the shoe when integrated in a sole.

[0113] The first element 310 has first material properties, whereas the second element 312 has second material properties. As illustrated, the insert 314 comprises a plurality of first elements 310 and a single second element 312. The second element 312 forms a plurality of substantial elongated protrusions. A first element 310 extends along each of the protrusions, thereby forming a plurality of sets of first and second elements 310, 312 extending in a longitudinal direction. The sets of first and second elements 310, 312 are arranged at a distance to each other to provide a gap 322 between the sets of first and second elements 310, 312. The gaps 322 facilitate deflection of the first and second elements 310, 312.EXAMPLE 1

[0114] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0115] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D, BASF Chemical Company) with a siloxane polymer (such as Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0116] The raw material was dried for 45 minutes in 80° vacuum.

[0117] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 50 bar and 10 cm 3< / s injection speed. The back pressure was set to 20 bar at 4 s back pressure time. The nozzle temperature was set to be 215 °C, with the front, middle and back nozzle set to 205 °C, 205 °C and 205 °C, respectively. A cooling time of 8 s was provided.EXAMPLE 2

[0118] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0119] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0120] The raw material was dried for 45 minutes in 80° vacuum.

[0121] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 45 bar and 6 cm 3< / s injection speed. The back pressure was set to 45 bar at 5s back pressure time. The nozzle temperature was set to be 225 °C, with the front, middle and back nozzle set to 220 °C, 215 °C and 215 °C, respectively. A cooling time of 20 s was provided.EXAMPLE 3

[0122] A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0123] A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0124] The raw material was dried for 45 minutes in 80° vacuum.

[0125] The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 35 bar and 20 cm 3< / s injection speed. The back pressure was set to 30 bar at 4s back pressure time. The nozzle temperature was set to be 230 °C, with the front, middle and back nozzle set to 225 °C, 220 °C and 220 °C, respectively. A cooling time of 30 s was provided.

Examples

example 1

[0114]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0115]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D, BASF Chemical Company) with a siloxane polymer (such as Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0116]The raw material was dried for 45 minutes in 80° vacuum.

[0117]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 50 bar and 10 cm 3< / s injection speed. The back pressure was set to 20 bar at 4 s back pressure time. The nozzle temperature was set to be 215 °C, with the front, middle and back nozzle set to 205 °C, 205 °C and 205 °C, respectively. A cooling time of 8 s was provided.

example 2

[0118]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0119]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0120]The raw material was dried for 45 minutes in 80° vacuum.

[0121]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 45 bar and 6 cm 3< / s injection speed. The back pressure was set to 45 bar at 5s back pressure time. The nozzle temperature was set to be 225 °C, with the front, middle and back nozzle set to 220 °C, 215 °C and 215 °C, respectively. A cooling time of 20 s was provided.

example 3

[0122]A manufacturing process for a shoe comprising a first material and a second material according to the invention.

[0123]A first material, 'hard' TPU with a Shore hardness D 40 or above (Elastollan ®< 1174D (BASF Chemical Company) with a siloxane polymer (Dow Corning ®< MB50-017 Masterbatch) is provided with a second material, 'soft' TPU is provided with a Shore hardness A 65 (Compound PYV RB 02 (065) from PY KG), in a compounder and was compounded according to the manufacturer's instructions.

[0124]The raw material was dried for 45 minutes in 80° vacuum.

[0125]The first and second material is then moulded using an aluminium resin. The moulding was conducted with an injection pressure of 35 bar and 20 cm 3< / s injection speed. The back pressure was set to 30 bar at 4s back pressure time. The nozzle temperature was set to be 230 °C, with the front, middle and back nozzle set to 225 °C, 220 °C and 220 °C, respectively. A cooling time of 30 s was provided.

Claims

1. A shoe comprising: a sole with a ground-engaging surface for engaging a ground; an edge; and a connecting portion interconnecting and extending between the ground-engaging surface and the edge; wherein: - at least one selected portion of the sole, the edge, or the connecting portion comprises two adjacent elements, a first one of which has first material properties, and a second one of which has second material properties, the two adjacent elements being disposed to enable deflection of the elements relative to one another when the selected portion is subjected to a force component parallel to the ground; and - the adjacent elements are disposed, configured and deflectable relative to one another such that: - application of the force component to the selected portion in a first direction results in a first coefficient of friction between the selected portion and ground, and - application of the force component to the selected portion in a second direction results in a second coefficient of friction between the selected portion and ground, wherein the first coefficient of friction is different from the second coefficient of friction.

2. The shoe according to claim 1, wherein the selected portion extends into the edge as well as into the sole of the shoe.

3. The shoe according to claim 1 or 2, wherein the first material properties comprise at least one of a Young's modulus and a first coefficient of friction, and wherein the second material properties comprise at least one of a second Young's modulus and a second coefficient of friction, and wherein each of the first and second elements define outwardly facing surfaces, each of which defines a portion of an outer surface of the sole, the connecting portion and / or the edge of the shoe, and wherein: - the first element has a Young's modulus of a first value and a first coefficient of friction on its outwardly facing surface; - the second element has a Young's modulus of a second value and a second coefficient of friction on its outwardly facing surface; - the value of the first Young's modulus is higher than the value of the second Young's modulus, and the first coefficient of friction is lower than the second coefficient of friction.

4. The shoe according to any of the preceding claims, wherein the elements are configured such that one of the elements deflects more than the other one when subjected to pressure to thereby render the surface friction of the selection portion dependent on the amount of pressure applied.

5. The shoe according to any of the preceding claims, wherein the first element is comprised in at least one insert secured to a portion of the sole of the shoe, such as a plurality of inserts, wherein the second element is optionally integrated with the sole of the shoe.

6. The shoe according to claim 5, wherein the second element is integrated with the sole of the shoe, and wherein sole of the shoe, except for the first element, and the second element are integrally formed from one and the same sole material.

7. The shoe according to any claim 5 or 6, wherein the at least one insert comprises a downward facing surface portion defining a portion of the sole of the shoe and a sideward facing surface portion defining a portion of the connecting portion and / or the edge of the shoe.

8. The shoe according to any of claims of claims 5-7, wherein the at least one insert comprises a plurality of downward facing surface portions defining respective spaced-apart portions of the sole of the shoe.

9. The shoe according to any of the preceding claims, wherein the at least one selected portion of the sole, the edge or the connecting portion is arranged at a tip portion of the shoe, and wherein the selected portion of the sole, the edge or the connecting portion optionally comprises a resilient backing structure for biasing the shoe away from ground in a backward movement of the shoe.

10. The shoe according to any of the preceding claims, wherein the at least one selected portion of the sole, the edge or the connecting portion is arranged at a lateral side edge of the shoe.

11. The shoe according to any of the preceding claims, comprising a gap or groove in an outwardly facing surface of the selected portion, wherein the gap or groove is disposed between the first and second elements.

12. The shoe according to any of the preceding claims, wherein the first of at least one selected portion of the sole, the edge or the connecting portion having first material properties comprises a first material and the second of at least one selected portion of the sole, the edge or the connection portion having second material properties comprises a second material, wherein the first material comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA), polyethylene such as ultra-high-molecular-weight polyethylene (UHMW-PE), synthetic rubbers, such as styrene-butadiene rubber (SBR), Styrene Butadiene Styrene, nylon or mixtures thereof with a Shore D hardness 40 or higher, and wherein the first material further comprises an additional material selected from the list comprising polymerized polysiloxanes such as polymerized silicone, polyethylene such as ultra-high molecular (UHMW) siloxane polymer, per- and polyfluoroalkyls (PFAS) such as polytetrafluoroethylene (PTFE), graphene, graphite or mixtures thereof, wherein the second material optionally comprises at least one polymer and / or copolymer, wherein the at least one polymer and / or copolymer is selected from the group comprising rubber, polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPEs) and Thermoplastic rubbers (TPR) such as ethylene propylene diene monomer rubber (EPDM rubber), styrene-butadiene rubber (SBR), polyvinylchloride (PVC), ethylene-vinyl acetate (EVA), or mixtures thereof with a Shore A hardness 50-85.

13. The shoe according to claim 12, wherein the weight% of the additional material is between about 5-30% based on the total weight of the first material, preferably about 15-25%, more preferably about 20-22% and most preferably about 20% based on the total weight of the first material, wherein the second material and the sole of the shoe are optionally integrally formed from one and the same sole material.

14. The shoe according to claim 13 or 14, wherein the first material comprises thermoplastic polyurethane (TPU) and polymerized silicone.

15. A method of manufacturing a shoe according to any of the preceding claims, wherein: - the first element is comprised in at least one insert secured to a portion of the sole of the shoe; - the second element is integrated with the sole of the shoe; - the sole of the shoe, except for the first element, and the second element are integrally from one and the same sole material; - the method comprising the step of co-moulding or co-extruding the first element with the sole material.

Images