Footwear

Abstract

A shoe 100 for discouraging or preventing toe-walking, comprising a sole 102 with an upper surface 110 defining a heel region, a ball region, and a toe region, wherein the sole is less resiliently com

Description

FIELD OF THE INVENTION The invention relates to footwear for discouraging toe-walking. Embodiments of invention have been developed largely for use in the discouragement and / or correction of toe-walking in children and adolescents during the primary period over which feet develop, and particularly in neurodivergent children and adolescents, and the invention is described herein with reference to that application. However, it will be appreciated that older and non-neurodivergent individuals may also benefit from the use of embodiments of the invention. BACKGROUND OF THE INVENTION Some children tend to toe-walk, which involves walking with the feet being less dorsiflexed and more plantarflexed in gait motion relative to children who do not toewalk, with the majority of the toe-walking child’s weight being born by the front of the ball of the foot. There are many potential causes of toe-walking. For example, neurodivergent individuals may have sensory issues that cause them to resist placing their foot flat on the ground. Unusually high or low muscle tone may result in an increased tendency to toe-walk. Toe-walking may also be idiopathic. Whatever the cause, frequent toe-walking can cause undesirable adaptations, including shortened calf muscles, changes in tendon (particularly the Achilles tendon) and ligament tension, other undesirable musculoskeletal changes throughout the body, and neuromuscular adaptations. Once a child becomes habituated to toe-walking, it can be challenging to slow or reverse the corresponding physical and neuromuscular adaptations. It is an object of the invention to overcome or at least address the issue of toe-walking. SUMMARY OF THE INVENTION In accordance with a first aspect, there is provided footwear for discouraging toe-walking, the footwear comprising: a sole comprising an upper surface, the upper surface defining: a heel region for engaging a heel of a wearer’s foot; a ball region for engaging a ball of the wearer’s foot; and a toe region for engaging toes of the wearer’s foot; wherein: the sole underneath and / or behind the heel region is less resiliently compressible than the sole underneath and / or forward of the ball region; and the sole is configured such that the heel region is lower than the ball region and / or the toe region when the sole is resting on a level surface. The combination of different resilient compressibility and the heel region being lower than the ball region and / or the toe region synergistically works to discourage toe-walking. A straight heel-ball line between the heel region and the ball region may define an angle of at least +5° degrees to the horizontal when the sole is resting on a level surface. This angle may improve stretching of tendons, ligaments, and / or musculature of the foot, lower limb, and / or ankle, e.g. by encouraging a posterior-to-anterior weight transfer without inducing excessive stretch across the posterior chain musculature. The materials and configuration of the sole may be such that the heel-ball line remains at a positive angle when the heel region and the ball region are compressed by the weight of a wearer standing stationary on level ground. This may discourage toe-walking and / or encourage a healthy heel-toe gait. A straight ball-toe line between the ball region and the toe region may define an angle of at least +5° to the horizontal when the sole is resting on a level surface. This may discourage toe-walking and / or encourage a healthy heel-toe gait. The materials and configuration of the sole may be such that the ball-toe line remains at a positive angle when the ball region and the toe region are compressed by the weight of a wearer standing stationary on level ground. This may discourage toe-walking and / or encourage a healthy heel-toe gait. The ball-toe line may define a greater angle to the horizontal than the angle defined by the heel-ball line, when the sole is resting on a level surface. The materials and configuration of the sole may be selected such that the heel region of the sole compresses proportionally less than the ball region and / or the toe region, during ordinary walking employing a heel-toe gait. This may discourage toe-walking and / or encourage a healthy heel-toe gait. The sole may comprise a foam material underneath at least the ball region. The sole may comprise a foam material underneath at least the heel region, the foam underneath the heel region being of, on average, higher density than the foam underneath the ball region. The sole may comprise a solid material underneath at least the heel region. Solid material may encourage a firm heel strike, which may discourage toe-walking and / or encourage a healthy heel-toe gait. The sole underneath and / or behind the heel region may comprise a first material and the sole underneath and / or forward of the ball region comprises a second material different to the first material. The use of different materials offers a convenient way of providing regions of different resilient compressibility. The first material may have a higher Shore A hardness than the second material. The footwear may comprise means for alternating the degree of dorsiflexion (or a means for inhibiting, reducing and / or discouraging dorsiflexion) (e.g, a stiffening component). The footwear may comprise a stiffening component that overlaps, in plan view, a region of the sole over which the metatarsophalangeal joint, in use, is positioned. Such a stiffening component may help control bending of the wearer’s foot and toes in the region of the metatarsophalangeal joint. Controlling bending in this region may discourage toe-walking and / or encourage a healthy heel-toe gait. In examples, the stiffening component may form part of the sole of the footwear. At least part of the stiffening component may extend rearward to at least a longitudinal midpoint of the ball region. At least part of the stiffening component may extend rearward beyond the longitudinal midpoint of the ball region, optionally to a longitudinal midpoint of the sole, or beyond. The stiffening component extending rearward in this way may improve bending control in the region of the metatarsophalangeal joint. At least part of the stiffening component may extend forward from the longitudinal midpoint of the ball region towards the toe region. At least part of the stiffening component may extend forward into or beyond the toe region. The stiffening component extending forward in this way may improve bending control in the region of the metatarsophalangeal joint. At least part of the stiffening component may taper, in plan view: forward of the longitudinal midpoint of the ball region; and / or rearward of the longitudinal midpoint of the ball region. Tapering of the stiffening component forward and / or rearward of the longitudinal midpoint of the ball region may provide for greater bend control at, or adjacent to, the longitudinal midpoint of the ball region. For example, the amount of bending control may reduce in the direction of the tapering of the stiffening component. The stiffening component may be removable. This may allow for the stiffening component to be replaced without the need to replace the sole or the footwear. For example, a stiffening component may be replaced by a further stiffening component of greater or lesser stiffness, in order to provide improved bending control. The stiffening component may be formed from any suitable material(s). For example, the stiffening component may be formed from one or more layers of flexible materials. In examples, the stiffening component is moulded from nylon or thermoplastic polyurethane. In examples, the stiffening component is formed from a fiber-reinforced polymer, such as glass and / or carbon-fiber reinforced nylon. The sole may comprise a recess for receiving the stiffening component. A recess may provide a convenient mechanism for correctly installing the stiffening component, while ensure correct positioning. The use of a stiffening component beneath the metatarsophalangeal (MTP) joint region may reduce flexion at the forefoot (e.g., anterior to the midfoot arch), during the stance and toe-off phases of gait. Limiting flexion at the MTP joints may discourage forefoot overloading and premature heel lift, which are common compensatory features in idiopathic toe-walking and other atypical gait presentations, particularly in children. The use of a stiffening component may promote a more typical heel-to-toe gait progression, encouraging controlled loading of the heel and midfoot zones. The footwear may comprise means for encouraging greater dorsiflexion through features that vary pressures on parts of the foot to reduce toe-walking and / or encourage a healthy heel-toe gait. The means for altering the degree of dorsiflexion (or the means for inhibiting, reducing and / or discouraging dorsiflexion) may comprise a strap configured to extend around an upper region of the wearer’s foot, adjacent to the wearer’s shin. This may assist in positioning the heel of the foot into the heel of the sole to discourage toe-walking and / or encourage a healthy heel-toe gait. The strap may be adjustable to allow adjustment of the pressure (or a force) placed by the strap on the wearer’s foot, shin, and / or ankle, when the footwear is in use. This may allow adjustment of the amount of dorsiflexion encouragement, which may improve results and / or allow for increased user compliance. Greater pressure (or more force) may position the heel more fully in position to discourage toe-walking and / or encourage a healthy heel-toe gait. The means for altering the degree of dorsiflexion (or inhibiting, reducing and / or discouraging dorsiflexion) may comprise a cable configured to extend around a rear of the footwear adjacent to an Achilles tendon and / or calf of the wearer. This may assist in positioning the lower leg forwards, which may discourage toe-walking and / or encourage a healthy heel-toe gait. The cable may be adjustable to allow adjustment of the pressure (or force) placed by the cable on the wearer’s foot, Achilles tendon, calf, or ankle, when the footwear is in use. This may allow adjustment of the amount of dorsiflexion encouragement, which may improve results and / or allow for increased user compliance. Greater pressure (or more force) may discourage toe-walking and / or encourage a healthy heel-toe gait. The footwear may comprise a ratchet mechanism for adjusting the cable when the footwear is in use. The means for altering the degree of dorsiflexion (or the means for inhibiting, reducing and / or discouraging dorsiflexion) may comprise an inflatable bladder. The use of an inflatable bladder may allow adjustment of the amount of dorsiflexion encouragement, which may improve results and / or allow for increased user compliance. Greater pressure (or more force) may discourage toe-walking and / or encourage a healthy heel-toe gait. The inflatable bladder may be configured to extend behind the foot, Achilles tendon, calf, or ankle, such that inflation of the bladder causes the bladder to position the foot, Achilles tendon, lower leg, calf, or ankle of the wearer forward and / or downward relative to the footwear. The inflatable bladder may be configured to extend above the foot adjacent to the shin, such that inflation of the bladder causes the bladder to position the foot, shin, or ankle of the wearer rearward and / or downward relative to the footwear. In accordance with a further aspect of the invention, there is provided footwear for discouraging toe-walking, the footwear comprising: a sole comprising an upper surface, the upper surface defining: a heel region for engaging a heel of a wearer’s foot; a ball region for engaging a ball of the wearer’s foot; and a toe region for engaging toes of the wearer’s foot; and, preferably, a stiffening component that overlaps, in plan view, a region of the sole over which the metatarsophalangeal joint, in use, is positioned, wherein: the sole is configured such that the heel region is lower than the ball region and / or the toe region when the sole is resting on a level surface. The combination of the heel region being lower than the ball region and / or the toe region, and the provision of stiffened component, synergistically works to discourage toe-walking. The footwear may comprise means for altering the degree of dorsiflexion of the wearer’s foot, such as any means for altering the degree of dorsiflexion as defined above. The use of such means for altering the degree of dorsiflexion of the wearer’s foot may synergistically work together to discourage toe-walking and / or encourage a heel-toe gait. In accordance with a further aspect of the invention, there is provided a corrective shoe having the features of any other aspect. In accordance with a further aspect of the invention, there is provided a corrective shoe for discouraging toe-walking in children and adolescents. In accordance with a further aspect of the invention, there is provided footwear for discouraging toe-walking, the footwear comprising: a sole comprising an upper surface, the upper surface defining: a heel region for engaging a heel of a wearer’s foot; a ball region for engaging a ball of the wearer’s foot; and a toe region for engaging toes of the wearer’s foot; wherein: the sole is configured such that the heel region is lower than the ball region and / or the toe region when the sole is resting on a level surface; and wherein: the footwear further comprises means for altering the degree of dorsiflexion (or means for inhibiting, reducing or discoursing dorsiflexion) of the wearer’s foot, such as any means for altering the degree of dorsiflexion (or means for inhibiting, reducing or discouraging dorsiflexion) as defined above. In accordance with a further aspect of the invention, there is provided a corrective shoe for discouraging toe-walking in a neurodivergent individual having sensory issues. In accordance with a further aspect of the invention, there is provided a sole unit comprising: a ground-contacting outsole layer and an upper-facing midsole layer; a stiffening component positioned beneath the metatarsophalangeal joint region of the foot, recessed within or integrated into the forefoot section of the midsole; wherein the stiffening component is configured to reduce forefoot flexion during gait, thereby promoting posterior-to-anterior weight transfer and encouraging a heel-to-toe gait pattern in individuals prone to forefoot-loading or toe-walking. The stiffening component may take the form of a stiffening component. The stiffening component may be constructed from a thermoplastic material selected from the group comprising thermoplastic polyurethane (TPU), nylon, or a functional equivalent having a high Shore A hardness (e.g. between 75 and 95). The stiffening component may span laterally across the forefoot region. The stiffening component may be shaped to maintain adequate bonding margins at its periphery. The stiffening component may be removable. The stiffening component may be non-removable and / or integrally bonded within the midsole to resist displacement under repetitive loading. The stiffness profile of the sole may vary across zones, with the forefoot offering increased rigidity relative to the heel and midfoot to manage load transfer and encourage posterior contact. The sole may be usable as a component of footwear to assist in the therapeutic management of atypical gait patterns including, but not limited to, habitual toewalking, idiopathic toe-walking, or sensory-seeking gait abnormalities. The outsole may comprise a series of protruding spherical or semi-spherical nodules arranged along the lateral and medial margins from heel to toe, configured to provide tactile feedback, traction, and / or lateral stability during gait. The spherical nodules may be constructed from a more rigid rubber compound than adjacent sole areas, having a medium-to-high Shore A hardness (e.g. greater than 60). This may resist deformation and promote consistent proprioceptive feedback. In accordance with a further aspect of the invention, there is provided a sole unit for use with the footwear of any aspect or example described and / or defined herein. BRIEF DESCRIPTION OF THE DRAWINGS Aspects and implementations will now be described, without limitation and byway of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a piece of footwear comprising a shoe, in accordance with an embodiment of the invention; Figure 2 is a longitudinal vertical section through the shoe of Figure 1; Figure 3 is a longitudinal vertical section through a wearer’s foot and the sole of the shoe Figures 1 and 2; Figures 4 and 5 are longitudinal vertical sections through the sole of Figure 3; Figure 6 is a plan view of the sole of Figures 2 to 5; Figure 7 is a longitudinal vertical section through a wearer’s foot and the sole of an alternative shoe, in accordance with a further embodiment of the invention; Figure 8 is a schematic side view of a piece of footwear comprising a shoe, in accordance with a further embodiment of the invention; Figures 9 and 10 are schematic side views of a piece of footwear comprising a shoe, in accordance with a further embodiment of the invention; Figures 11 and 12 are schematic side views of a piece of footwear comprising a shoe, in accordance with a further embodiment of the invention; Figures 13 and 14 are schematic side views of a piece of footwear comprising a shoe, in accordance with a further embodiment of the invention; Figures 15 to 17 are respective underside, side elevation, and longitudinal vertical sections through a sole for use with footwear comprising a shoe, in accordance with a further embodiment of the invention; Figures 18 and 19 are, respectively, a plan view and side elevation of an insole for use with embodiments of the invention; Figure 20 is a simplified plan view of a sole for a piece of footwear comprising a shoe, in accordance with a further embodiment of the invention; Figure 21 is a longitudinal vertical section through the sole of Figure 20; Figure 22 is a plan view of a stiffening component for use with the sole of Figures 20 and 21; Figure 23 is the longitudinal vertical section through the sole of Figure 20, with the stiffening component of Figure 22 installed; and Figure 24 is the plan view of the sole of Figure 20, with the stiffening component of Figure 22 installed. DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, Figures 1 to 7 show an embodiment of toe-walking reduction footwear in the form of a shoe 100. Although only a single shoe is shown, it will be appreciated that the footwear will generally be provided in a pair. While the pieces of footwear in a pair will typically match each other, in other cases, individual shoes can be adapted to meet the musculoskeletal needs of the intended wearer. For example, a leg-length disparity can be accounted for in the relative heights of the soles of the footwear. The shoe 100 comprises a sole 102. In the embodiment of Figures 1 to 7, the sole 102 takes the form of a single piece component. It will be appreciated that, in other embodiments, the sole 102 can comprise a composite component including, for example, an insole (which may be removable), a midsole, and / or an abrasion-resistant outsole. The shoe 100 comprises an upper 104 extending upwards from the sole 102. In the illustrated impediment, the upper 104 takes the form of a seamless elastic knitted “sock” construction. The lack of seams and fastening components such as laces, straps, or buckles may reduce sensory issues for some wearers. An upper edge of the upper 104 terminates at a ribbed cuff 106. The cuff 106 may be more heavily elasticated than the rest of the upper 104, which helps retain the shoe 100 on the wearer’s foot. A loop 108 extends from a rear of the upper 104, to assist with pulling the shoe 100 onto the wearer’s foot. A reinforcing strip 194 is provided between the upper edge of the sole 102 and the upper 104. The reinforcing strip 194 is stitched to the upper 104 and bonded to the inside of the sole 104. However, in other embodiments, a reinforcing strip can be bonded, welded, co-moulded, or otherwise attached. The reinforcing strip 194 helps reduce sliding and other movement of the foot while the wearer is walking, running, or otherwise moving. The sole 102 comprises an upper surface 110. In the illustrated embodiments, the upper surface 110 covers the entire top surface of the sole 102. The upper surface 110 is designed to engage the underside of a wearer’s foot, as described in more detail below with reference to Figure 3. Where an insole or liner is used, the upper surface 110 may be the upper surface of the insole. Alternatively, the upper 104 may extend underneath the foot of the wearer, in which case the upper surface 110 may be the surface of the upper 104 that is in contact with the sole of the foot. As best shown in Figure 6, the upper surface 110 defines a heel region 112 for engaging the heel of a wearer’s foot, a ball region 114 for engaging a ball of the wearer’s foot, and a toe region 116 for engaging toes of the wearer’s foot. It will be appreciated that the heel region 112, the ball region 114, and the toe region 116 need not necessarily be defined by a particular material, structure, or marking on the upper surface 110. Instead, the heel region 112, the ball region 114, and the toe region 116 represent general areas of the upper surface 110 within which the heel, ball, and toes of a typical wearer’s feet would be expected to contact the upper surface 110 while the shoe 100 is being worn. As best shown in Figures 3 to 5, the sole 102 is configured such that the heel region 112 is lower than the ball region 114 and / or the toe region 116. Figure 3 shows a longitudinal section through the sole 102, with the upper 104 removed for clarity, and a wearer’s foot 118 in the position it would be while wearing the shoe 100. The foot 118 includes a heel 120, arch (or instep) 122, ball 124, and toes 126. The lower leg 148 rises from the foot 118. At the rear of the foot 118 and the lower leg 148, the Achilles tendon 162 rises up to join the lower calf 164. The shin 150 is located at the front of the lower leg 148. The heights of various positions across the upper surface 110 can be determined when the sole 102 is resting on a level surface. It is the relative heights of the position that are important. As such, the heights can be measured from, for example, the level surface, or from another datum, such as the lowest point of the upper surface relative to the level surface. The height of the heel region 112 can be measured at a heel position 128 within the heel region 112 that corresponds with the lowest point of the calcaneus bone of a typical human foot, in a typical wearer of the shoe. Alternatively, the height of the heel region 112 can be taken as an average height of the heel region 112 measured across a width of the heel region 112, or across a width of the upper surface 110 in line with the lowest point of the calcaneus bone of a typical human foot, fora typical wearer of the shoe. The height of the ball region 114 can be measured at a ball position 130 within the ball region 114 that corresponds with the first metatarsophalangeal joint of a typical human foot. Alternatively, the height of the ball region 114 can be taken as an average height of the positions within the ball region 114 of all first metatarsophalangeal joints, fora typical wearer of the shoe. The height of the toe region 116 can be measured at a toe position 132 within the toe region 116 that corresponds with the mid-pad of the distal phalange of the big toe of a typical human foot. Alternatively, the height of the toe region 116 can be taken as an average height of the positions within the toe region 116 of the mid-pads of all distal phalanges of the toes. The heel region 112 may be lower than both the ball region 114 and the toe region 116. In addition, the ball region 114 may be lower than the toe region 116. Figure 4 shows the sole 102 without the foot 118. A straight heel-ball line 134 extends from the heel position 128 to the ball position 130. Although the heel-ball line 134 extends entirely above the upper surface 110 in Figure 4, in other embodiments, the shape of the upper surface 110 may mean that the heel-ball line 134 extends through a portion of the sole 102. The heel-ball line 134 is at an angle 136 of greater than 0° to the horizontal when the sole 102 is resting on a level surface and not being worn by a wearer. It may be desirable for the heel-ball line 134 to be at an angle 136 that is greater than 3°, 5°, or 7° to the horizontal when the sole 102 is resting on a level surface and not being worn by a wearer. In the illustrated embodiment, the heel-ball line 134 is at an angle of approximately 9° to the horizontal when the sole 102 is resting on a level surface and not being worn by a wearer. A straight ball-toe line 138 extends from the ball position 130 to the toe position 132. Although the ball-toe line 138 extends entirely above the upper surface 110 in Figure 4, in other embodiments, the shape of the upper surface 110 may mean that the balltoe line 138 extends through a portion of the sole 102. The ball-toe line 138 is at an angle 140 of greater than -5° to the horizontal when the sole 102 is resting on a level surface and not being worn by a wearer. It may be desirable for the ball-toe line 138 to be at an angle 140 that is greater than 0°, 5°, or 10° to the horizontal when the sole 102 is resting on a level surface are not being worn by a wearer. In the illustrated embodiment, the ball-toe line 130 is at an angle of approximately 15° to the horizontal when the sole 102 is resting on a level surface and not being worn by a wearer. As shown in Figure 5, a straight heel-toe line 152 extends from the heel position 128 to the toe position 132. Although the heel-toe line 152 extends entirely above the upper surface 110 in Figure 5, in other embodiments, the shape of the upper surface 110 may mean that the heel-toe line 152 extends through a portion of the sole 102. In the embodiments of Figures 1 to 6, the heel-toe line 152 is at a greater angle than the heel-ball line 134 and at a lower angle than the ball-toe line 138. The angle of the heel-ball line 134, the ball-toe line 138, and / or the heel-toe line 152, place at least part of the foot at an angle to the horizontal that increases stretch on the calf, and ligaments and tendons (particularly the Achilles tendon) of the lower leg. This stretch can optionally be increased by angling the rear of the upper 104 forward relative to that of a conventional shoe. This forward angle reduces the angle between the sole of the foot and the lower leg (i.e., increases dorsiflexion). Various additional mechanisms can be used to encourage the foot and lower leg to more closely follow the angle established by the shoe, as described in more detail below. The sole 102 underneath the heel region 112 is less resiliently compressible than the sole 102 underneath the ball region 114. Resilient compressibility can be determined with reference to any suitable compressibility unit. For example, the resilient compressibility may relate to the relationship between pressure and linear compression. For example, a material that compresses to 50% of its starting dimension in response to a particular linear pressure is more compressible than a material that compresses to 75% of its starting dimension, assumingthe same dimensions. Compressibility may also be a factor of the physical characteristics of the material being considered. For example, the same polymer is more compressible as a foam than as a solid. Similarly, a component that includes one or more voids will be more compressible than a component of the same size and material that does not have cut-outs. The Shore hardness of the materials used in the sole 102 may contribute to the overall resilient compressibility of the various regions of the sole, as described in more detail below. For example, a solid rubber-based material having a relatively high Shore A hardness is less compressible than a polyurethane foam having a relatively low Shore A hardness. Combining different materials having different Shore hardnesses will complicate calculating the local resilient compressibility, especially where several overlapping and / or geometrically complex layers of materials are involved. Nevertheless, the skilled person will understand how the Shore hardness(es) of material(s) used to construct the sole will impact local resilient compressibility. In the embodiments of Figures 1 to 7, the sole 102 comprises an aft region 142 formed from a first material and a forward section 144 formed from a second material. The aft region 142 and the forward region 144 meet at line 178. The line 178 is chevronshaped in the embodiment of Figures 1 to 7, but any other line shape may be employed to suit the functional and aesthetic requirements of the intended application. The heel region 112 is completely within the aft region 142, although in other embodiments, only a portion of the heel region 112 is within the aft region 142. In yet other embodiments, the aft region 142 is partly, substantially or completely disposed aft of the heel region 112. The ball region 114 and the toe region 116 are both completely within the forward region 144. The first material and the second material are selected and configured to have relatively different levels of resilient compressibility. In particular, the first material is selected and configured to be less resiliently compressible than the second material. The difference in resilient compressibility between the first material and the second material can arise from the basic material properties of the selected material. For example, a stiff rubbery material such as ethylene-propylene diene monomer rubber (EPDM) is typically less resiliently compressible than a foam such as closed-cell ethylenevinyl acetate (EVA) copolymer foam. Shore hardness (such as Shore A hardness) is one way of defining the hardness of a material, which relates to its compressibility. As a non-limiting example, a rubber material used in the heel region may have a Shore A hardness of 50 while a foam material used in the ball region may have a Shore A hardness of 45. In an alternative example, a rubber material used in the heel region may have a Shore A hardness of 55-58 while a foam material used in the ball region may have a Shore A hardness of 50. The Shore hardnesses of the materials of a particular design may be selected based on the surface area of the regions, the anticipated weight of the wearer (e.g., a larger size shoe will typically be for a heavier wearer), the relative heights of the regions, and the effect of any cutouts or the like over overall compressibility. The difference in compressibility between the first material and the second material can alternatively, or in addition, be a result of a production method used to manufacture the selected material. For example, a foamed polymer material is typically more resiliently compressible than a solid version of the same polymer material. Similarly, an open-celled version is typically more resiliently compressible than a closed-cell version of the same polymer material. The difference in compressibility between the first material and the second material can alternatively, or in addition, be a result of post-manufacture modifications to the selected material. For example, cutting, engraving, embossing, melting, moulding, or otherwise forming recesses, hollows, holes, or other features into a material can change its resilient compressibility in one or more directions. Any combination of material, production method, and post-manufacture modifications can be selected for each of the first material and the second material to provide the desired resilient compressibility forthat material. Either or both of the first material and the second material can be a composite of more than one material type. Each material type can also be subject to one or more production methods and / or post-manufacture modifications, for example as described above, such that the resultant composite material provides the desired resilient compressibility. As an example, either or both of the first and second material can be formed from two or more layers of different materials (“different” in the sense of material type, production method, and / or post-manufacture modifications, for example). The sole 102 may comprise a foam material underneath at least the ball region. For example, in the embodiment of Figures 1 to 7, the forward region 144 is formed from a polyurethane foam. The sole 102 may comprise a foam material underneath at least the heel region 112. The material of the sole 102 under the heel region 112 may be of, on average, higher density than the material of the sole 102 underneath the ball region 114. As one example, where the sole 102 comprises a foam material underneath both the heel region 112 and the ball region 114, the foam underneath the heel region 112 may be of, on average, higher density than the foam underneath the ball region 114. The sole 102 may at least partly comprise a solid material underneath at least the heel region 112. For example, in the embodiment of Figures 1 to 6, the aft region 142 is formed from EPDM. In other embodiments, different solid materials such as nonfoamed polymers may be employed. In use, the shoe 100 is worn by a wearer. The shoe can be worn by a wearer who is currently a toe-walker, to reduce the appeal of toe-walking. The shoe can also be worn by a wearer who is not yet a frequent toe-walker, but is considered to be at risk of becoming a toe-walker as a result of current behaviours. Early intervention is likely to improve long-term results. As explained above, the shoe 100 will typically be worn as a pair where the wearer has two feet, since it is commonly the case that toe-walkers walk on the toes of both feet. It would also in general, be undesirable to mix significantly different shoe types without a good orthopaedic reason for doing so. Compared with conventional shoes having a raised heel (relative to the ball and toe), the positive angle between the heel region 112 and the ball region 114 of the shoe 100 requires additional force for the wearer to move from being flat-footed to being on their toes. This discourages the wearer from initiating toe-walking. The positive angle between the heel region 112 and the ball region 114 requires even more force to move onto the toes than being bare-foot, for example. In addition, the positive angle causes a stretch in the calf muscles and Achilles tendon while the shoes 100 are beingworn. Overtime, these stretches improve flexibility and mobility of the lower limbs, ankle joints, and feet, which may at least partly counteract undesirable musculoskeletal and / or neuromuscular adaptations that may make breaking the toe-walking habit more challenging. The difference in resilient compressibility between the heel region 112 and the ball region 114 works synergistically with the positive angle between the heel region 112 and the ball region 114. For example, the lower resilient compressibility of the sole 102 at the heel region 112 provides a firm heel plant while walking. Without wishing to be bound by any theory, it is believed that a firm heel plant may assist in the process of the body neuro-muscularly adapting to a healthier heel-toe gait. In addition, where the wearer is capable of understanding the importance of heel plant, the less resiliently compressible material around the heel may provide good feedback to the wearer during heel plant. In addition, the higher resilient compressibility of the sole 102 atthe ball region 114 may promote a softer roll forward onto the balls of the feet. This eases the perceived transition from the relatively firm heel plant, especially given that the heel region 112 is lower than the ball region 114. Again without wishing to be bound by any theory, it is believed that the transition from firm heel plant to softer forefoot landing may encourage the development of a healthier heel-to-toe gait. As one non-limiting example, the heel region 112 may be configured such that a downward force of 10 kg (for example) applied evenly across the heel region 112 causes compression of the heel region by at least 0.5, or typically 1 mm, while the ball region 114 may be configured such that a downward force of 10kg (for example) applied evenly across the ball region 114 causes compression of the ball region 114 by at least 1 mm, or typically 1.5 to 2.5 mm. Optionally, the footwear can include one or more nodules that extend downwards and optionally outwards from the sole 102. In the embodiment of Figures 1 to 7, the nodules take the form of bulbous features 190 defined by sidewalls 192. The bulbous features 190 extend from an underside of the sole. At least underthe ball region 114, the bulbous features 190, as measured by the linear depth of the sidewalls 192, comprise at least 50%, and more preferably 60% or 70%, of the total thickness of the sole 102, as measured from the upper surface to the underside of the bulbous feature 190. At least some of the bulbous features 190 include a hollow underside 196, which may improve grip. Some of the nodules (e.g., bulbous features 190) may extend outwards beyond the rest of the shoe 100 to provide a bumper to protect the wearer’s foot. Optionally, at least one of the bulbous features 190 that at least partly underlies the ball region 114 has a greater volume than all the other bulbous features 190. Optionally, exactly one of the bulbous features 190 that at least partly underlies the ball region 114 has a greater volume than all the other bulbous features 190. Optionally, at least one of the bulbous features 190 that at least partly underlies the ball region 114 has less of a hollow than any of the other bulbous features 190, or no hollow. Optionally, exactly one of the bulbous features 190 that at least partly underlies the ball region 114 has less of a hollow than any of the other bulbous features 190, or no hollow. Optionally, exactly one of the bulbous features 190 that at least partly underlies the ball region 114 has a greater volume than all the other bulbous features 190 and has less of a hollow than any of the other bulbous features, or now hollow. An example of such a bulbous feature 190 is indicated with reference sign 198. The use of bulbous features may improve grip and wearer feedback. In addition, the use of such bulbous features at least partly underthe ball region 114 may synergistically work with the other features of the footwear to discourage toe-walking. For example, one or more relatively large bulbous feature positioned centrally under the ball region 114 may discourage the wearer from tilting forward onto their toes, due to a feeling of instability as the foot rocks forward on the large bulbous feature. The nodules may induce mild proprioceptive feedback movements to encourage muscle and tendon movement and stretch to promote a playful heel-to-toe gait experience. Although the bulbous features take the form of part-spherical bulbs, it will be appreciated that they may take other forms, such as cylinders, prisms, or any other regular or irregular solid. Optionally, at least a portion of lower surfaces of one or more of the bulbous features may be coated or covered by a layer of wear-resistant material, such as thermoplastic rubber, to improve grip and / orwear resistance. Optionally, the upper surface 110 can include one or more sensory features. For example, the upper surface 110 can include at least one textured region. Such sensory features can be formed on / in, or attached to, the upper surface of the sole 102. Alternatively, such sensory features can be formed on an insole, which may optionally be removable. The inclusion of sensory features may encourage a sensory-seeking wearer to plant their heel more firmly onto the floor. Sensory features may be selected to improve comfort more generally. This may make the shoe more tolerable to the wearer, which may be particularly beneficial if the wearer is neurodivergent or otherwise sensitive to the feel of the sole undertheirfeet. Figures 18 and 19 show an example of a textured insole 184 for use with the shoe 100 (or any of shoes 200, 300, 400, and 500, and other embodiments). The textured insole 184 includes ring-shaped bosses 186 extending upwards from the surface of the insole 184. The distribution of the bosses 186 across the insole 184 provides additional sensation to the wearer’s foot at various positions. For example, a denser group 188 (in this case, diamond-shaped) of the bosses underthe heel may encourage a firm heel plant. In other embodiments, sensory features are provided in only the rear half of the shoe. Optionally, allorat least a majority of the sensory features, ora majority of the surface area covered by the sensory features, may be located in only the rear half of the shoe. Optionally, one or more removable sole inserts can be provided, to adjust to the relative heights between the heel region 112, ball region 114, and toe region 116. For example, Figure 7 shows the shoe of Figures 1 to 6 with a sole insert in the form of a heel wedge 146. The heel wedge 146 extends forwards from the rear of the sole 102 underneath the heel 120. The heel wedge 146 raises the heel 120 relative to the upper surface 110, which reduces the angles 136 and 140. The shoe 100 can be provided with one or more removable sole inserts, such as heel wedges 146, ball wedges (not shown), and toe wedges (not shown) to customise the relative heights of the respective heel region 112, ball region 114, and toe region 116, for a particular wearer. Alternatively, or in addition, one or more sole inserts can be provided that cover two or more of the heel region 112, the ball region 114, and the toe region 116. For example, a sole insert can take the form of a removable insole (not shown) covering substantially all of the upper surface 110. The insole can have different thicknesses at each of the heel region 112, the ball region 114, and the toe region 116. Alternatively, or in addition, one or more removable or adjustable shoe inserts (not shown) may be provided at other locations within the footwear. For example, a compressible pad (not shown) positioned inside the upper rear of the footwear will increase pressure on the Achilles tendon and / or calf. This may increase the pressure to position the lower leg 148 forward, to alter the degree of dorsiflexion relative to the shoe without the insert. As another example, a compressible pad (not shown) positioned near the region between the upper midfoot and the lower shin will increase pressure on this region towards the lower rear of the footwear. This may increase the pressure to position the lower leg 148 forward, to alter the degree of dorsiflexion relative to the show without the insert. Two or more compressible pads of this general type may be combined to suita particular wearer’s needs. Such pads can be attached in any suitable manner, such as via hook-and-loop fasteners or the use of pockets within the lining of the shoe into which the pads can be inserted. As one example of the use of such sole inserts, a child using the shoe 100 for the first time may find the amount of stretch placed on the calf muscle and Achilles tendon by the positive heel-ball angle 136 uncomfortable. By using the heel wedge 146 while initially wearingthe shoe 100, the heel 120 is raised, which reduces the angle between the sole of the foot 118 and the shin 150. The child may find this more comfortable. The heel wedge 146 can be removed or replaced by a lower heel wedge 146 as the child becomes accustomed to the stretch caused by the positive heel-ball angle. Optionally, the materials and configuration of the sole 102 are selected such that the heel-ball line 134 and / or the ball-toe line 138 remains at a positive angle when the ball region 114 and / or the toe region 116 are fully compressed by the weight of a wearer standing stationary on level ground. Optionally, the materials and configuration of the sole 102 are selected such that the heel region 112 of the sole 102 compresses proportionally less than the ball region 114 and / or the toe region 116, during ordinary walking employing a heel-toe gait. This may provide a smooth transition as the weight moves from the wearer’s heel to toe during a stride. This may encourage a healthy heel-toe gait. Optionally, the shoe 100 may comprise means for altering the degree of dorsiflexion (or means for inhibiting, reducing or discouraging dorsiflexion, which may optionally be referred to as an alternative to a means for altering the degree of dorsiflexion where the latterterm is used hereinafter, where the context allows). Dorsiflexion involves movement of the upper part of the foot towards the shin. Figure 8 shows an embodiment of a shoe 200 including means for altering the degree of dorsiflexion. The shoe 200 shares many features with the shoe 100, and common features are indicated with like reference numerals. The means for altering the degree of dorsiflexion in shoe 200 includes a strap 154. The strap 154 is releasably connected to the upper 104 underneath the ankle, byway of a connector 156. The connector 156 can include a snap fastener, a buckle, a hook-and-loop materials, or any other suitable releasable connection mechanism. The other end (not visible) of the strap 154 is connected to the upper 104 at a position (not shown) underneath the ankle on the opposite side of the wearer’s foot. In use, with the connector 156 disconnected, the shoe 100 is placed onto the wearer’s foot 118. The strap 154 is then pulled tight across the top of the upper part of the upper 104 as shown in Figure 8, and attached via the connector 156. Tighteningthe strap 154 in this position causes the upper portion of the foot adjacent to the shin to be positioned backwards and downwards towards the rear of the shoe 200. This encourages the heel of the foot to sit in the heel of the sole, which works synergistically with the other features described above to discourage toe-walking. Optionally, the strap 154 and / or the connector 156 allow for adjustment of the strap length, and hence the amount of pressure placed on the upper foot of the wearer. Optionally, the strap 154 is flexible, which allows for continuous pressure while allowing some dorsiflexion. This may encourage a healthy heel-toe gait while discouraging toewalking. The strap 154 may be made sufficiently stiff that it provides a secure cage for the wearer’s foot and ankle joint to sit in as they walk. This cage may increase wearer comfort and compliance by reducing the sensation of toppling backwards due to the positive heel-ball angle 136. Figure 9 and 10 show an alternative embodiment of a shoe 300 including means for altering the degree of dorsiflexion. The shoe 300 shares many features with the shoes 100 and 200, and common features are indicated with like reference numerals. The means for altering the degree of dorsiflexion in shoe 300 includes an adjustable cable 180. The cable 180 extends from one side of a ratchet mechanism 166, along the side of the upper 104 through side support loops 158, through a rear support loop 160, and back through similar side loops (not shown) on the other side of the shoe 300 before returning to the ratchet mechanism 166. It will be appreciated that the support loops 158,160 are a form of cable guide, and that any other form of cable guide may be used instead of, or in addition to, the support loops 158. For example, any one or more of the support loops 158,160 may be replaced by one or more eyelets, sheathes, conduits or the like. Alternatively, or in addition, one or more of the support loops 158,160 may be omitted. The shoe 300 includes a movable counter 182 that extends vertically along the rear of the shoe 300. The counter 182 overlays, but is not directly stitched or otherwise attached to the adjacent upper 104. This allows the counter 182 to slide backwards and forwards relative to the adjacent upper 104. The rearmost portion of the counter 182 is relatively stiff in the vertical direction. The ratchet mechanism 166 may take the form of one of those known from, for example, adjustable snowboarding boots. Turning a dial 166 of the ratchet mechanism 166 in one direction causes both ends of the cable 180 to be drawn onto a spool (not shown) within the ratchet mechanism 166. A ratchet and pawl arrangement (not shown) latches the spool as it rotates. As such, the cable remains taught upon releasing the dial. Tightening the cable 180 with the ratchet mechanism 166 pulls the counter 182 in the region of the rear support loop 160 forwards. Because of the counter’s relative stiffness, the pressures placed on the counter 182 by the cable 180 in the region of the rear support loop 160 are transferred along the length of the counter 182 above and below the rear support loop 160. This causes a forward pressure to be applied along the rear of the wearer’s foot and Achilles tendon 162, which draws the lower leg 148 forwards, altering the degree of dorsiflexion of the foot. Figure 10 shows loosened position of the counter 182 in grey line, and the tightened position of the counter 182 in black line. Because the lower portion of the counter 182 is fixed to (or adjacent to) the sole 102, it cannot move as much as the upper portion of the counter 182 near the loop 108. As such, the counter 182 pivots forward rather than sliding directly forward. The cable 180 can be loosened by depressing the dial 166, which releases the internal ratchet and allows the cable 154 to loosen. In other implementations, the cable 180 can be loosened by turningthe dial 166 in the opposite direction to that which caused the cable 180 to tighten. Figures 11 and 12 show an alternative embodiment of a shoe 400 including means for altering the degree of dorsiflexion. The shoe 400 shares many features with the shoes 100, 200, and 300, and common features are indicated with like reference numerals. Although Figures 11 and 12 show the strap 156, it will be appreciated that the strap is optional. The means for altering the degree of dorsiflexion in the shoe 400 includes a bladder 170. The bladder 170 is positioned atthe rearof the upper 104. Although the bladder 170 is shown as beingwholly disposed adjacentto rearthe innersurface of the upper 104, it will be appreciated that this view is schematic. The bladder 170 will typically be encapsulated between an outer layer of the upper 104 and an inner liner. The bladder 170 can also take any suitable three-dimensional form required to provide pressure in the correct place. A pump 172 is disposed on the outer surface of the upper 104. The pump 172 comprises a hollow hemisphere 174 formed from a flexible rubber material. The pump 172 also comprises a conduit 176 that fluidly connects the interior of the hemisphere 174 to the interior of the bladder 170. The pump 172 also comprises a one-way valve (not shown) for preventing pressurised air from the interior of the bladder 170 from returning to the pump 172. Once the shoe 400 is on the wearer’s foot, the pump 172 is operated by repeatedly pushing on the outer surface of the hemisphere 174. The hemisphere 174 collapses inwards, causing an increase in air pressure within its interior. Air passes through the conduit 176 into the interior of the bladder 170, causing it to inflate. The one-way valve (not shown) prevents return of the air from the bladder 170 into the hemisphere 174 as the hemisphere 174 reinflates. Inflation of the bladder 170 is shown in Figure 12. The forward surface of the bladder 170 pushes against the rear of the foot and / or the Achilles tendon of the wearer, altering the degree of dorsiflexion. Optionally, the bladder 170 may be configured such that it applies more pressure higher up the Achilles tendon and / or on the lower calf 164. This may be achieved by, for example, having a cross-section of the bladder 170 increase in an upward direction along the Achilles tendon and / or lower calf 164. This may increase the pressure positioning the lower leg 148 forward, further altering the degree of dorsiflexion. Figures 13 and 14 show an alternative embodiment of a shoe 500 including means for altering the degree of dorsiflexion. The shoe 500 shares many features with the shoes 100, 200, 300, and 400, and common features are indicated with like reference numerals. Although Figures 13 and 14 show the strap 156, it will be appreciated that the strap is optional. The means for altering the degree of dorsiflexion in shoe 500 includes the bladder 170. However, in the embodiment of Figures 13 and 14 and 15, the bladder 170 extends along the highest point of the forefoot and the lower part of the shin. As with the embodiment of Figures 11 and 12, it will be appreciated that the views of Figures 13 and 14 are schematic. The bladder 170 will typically be encapsulated between an outer layer of the upper 104 and an inner liner (not shown), although this is not necessarily the case. Once the shoe 500 is on the wearer’s foot, the pump 172 is operated by pushing on the outer surface of the hemisphere 174, in a similar manner as was described in relation to Figures 11 and 12. Inflation of the bladder 170 is shown in Figure 14. The rearward surface of the bladder 170 pushes against the upper surface of the foot and the forward surface of the lower shin, altering the degree of dorsiflexion. The amount of force generated by the bladder 170 of shoes 400 and 500 can be controlled based on the number and firmness of the pushes on the hemisphere 174. The bladder 170 of shoes 400 and 500 can be deflated (or its internal pressure reduced) by operating a release valve (not shown), which allows air to escape from the interiorof the bladder 170. The pump 172 and / or bladder 170 can be positioned elsewhere on the shoes 400, 500. The pump 172 can also take any other suitable form. Depending upon the intended function and application of the shoes 300, 400, and 500, the means for altering the degree of dorsiflexion can provide anything from gentle pressure through to a relatively firm pressure to alter the degree of dorsiflexion. It may be desirable in some applications to allow adjustment between the full range of such pressures. In other applications, it may be desirable to allow adjustment between a subset of the full range of such pressures. By way of non-limiting examples, it may be desirable to provide up to 2°, 4°, or 6° of adjustment in dorsiflexion. Providing adjustable dorsiflexion control also allows the shoes 300, 400, and 500 to be adapted as the wearer becomes accustomed to wearing them. The change in dorsiflexion control may also provide visible, positive feedback of progress that the wearer may find encouraging. Figures 15 to 17 show an alternative sole 202. The sole 202 can be used with any of shoes 100, 200, 300, 400, and 500, and any other suitable embodiment. The sole 202 shares many features with the sole 102, and common features are indicated with like reference numerals. The sole 202 includes a rubber aft region 142 (shaded in grey) and an EVA forward region 144. As best shown in Figure 17, the sole 202 includes an overlap region 204, in which a rear portion of the forward region 144 overlaps a forward portion of the aft region 142. Even though some EVA is used underthe heel region in the sole 202, the overlapping rubber and EVA is less resiliently compressible than the EVA (-only) portion of the forward region 144. Other forms of overlap between materials used in the aft region 142 and the forward region 144 may also be employed in different embodiments. Figures 20 to 24 show a further embodiment of a sole 302 for use with embodiments of toe-walking reduction footwear, such as any of the shoes 100, 200, 300, 400, 500. As shown in Figures 20 and 21, the sole 302 comprises a recess 304. In this example, the recess 304 is diamond-shaped in plan view. In other examples in which such a recess is provided, the recess may take any other suitable shape in plan view, as described in more detail below. The recess 304 is generally aligned with the ball region 114. The recess 304 extends forwards towards the toe region 116. In examples, the recess may extend to, into, or beyond, the toe region. The recess extends rearwards towards a longitudinal midpoint of the sole 302. In examples, the recess may stop short of the longitudinal midpoint of the sole 302. In examples, the recess may extend rearwards to, or beyond, the longitudinal midpoint of the sole 302. In this example, the sole 302 includes nine optional holes 306 extending vertically down from an upper surface of the sole 302 around the ball region 114. In some examples in which such holes are provided, there may be more or fewer holes. Any suitable number of such holes may be provided. In examples, at least three such holes, or at least five such holes may be provided. A range of five to twelve holes has been found particularly effective in at least some examples. In some examples in which such holes are provided, at least some of the holes may extend to a greater or lesser depth within the sole, compared with the depths of the holes 306 shown in the example of Figures 20 to 24. In other examples in which such holes are provided, at least some of the holes may be positioned, in plan view, at different locations, compared to the locations of the holes 306 shown in the example of Figures 20 to 24. Optionally, one or more of the holes 306 is aligned with one or more of the bulbous features 190. The holes 306 enable air to be released when the sole 302 is compressed due to downward pressure from the ball of the wearer’s foot when the shoe is in use. Such downward pressure can arise during, for example, heel-to-toe weight transfer while walking. The release of air may improve compressibility of the sole, particularly around the ball region, which may encourage stretching of the wearer’s calf, ligaments, and tendons (and particularly the Achilles tendon) of the lower leg, and / or may encourage dorsiflexion, which may in turn may encourage a healthy heel-to-toe gait. Holes such as the holes 306 may also be implemented in any of the other embodiments disclosed herein. Figure 22 shows a stiffening component 308 for use with the sole 302. In this example, the stiffening component 308 is diamond-shaped in plan view. In this example, the shape of the stiffening component 308 is generally complementary with that of the recess 304. In other examples, the stiffening component may take any other shape in plan view. For example, the stiffening component may be kite-shaped, lozenge-shaped, leafshaped, oval, rectangular, or square, or may take the form of any simple or complex shape including curved and / or straight sides. In examples, the stiffening component may be configured to allow for an adequate bonding margin (e.g., at least 10mm) between the sole and the upper. In the illustrated example, the stiffening component 308 is formed from nylon, but any other suitable material(s) or combination of materials may be employed in other examples. For example, the stiffening component may be formed from thermoplastic polyurethane. For example, the stiffening component may be formed from two or more layers of different materials, and / or from one or more composite materials. The stiffening component may be at least partly composed of a fiber-reinforced polymer, such as glass and / or carbon-reinforced nylon or any other polymer. In examples, the stiffening component may be formed from a material or materials have a high Shore A hardness (for example of 75-95). In the illustrated example, the stiffening component is formed from nylon having a Shore A hardness of 85-95. Other Shore A hardnesses above or below this range may be used, depending upon the requirements of the implementation. In the illustrated example, the widest portion of the stiffening component 308 is positioned approximately in line with a centre of the ball region 114. In other examples, the widest portion of the stiffening component 308 may be positioned to be approximately in line with the region of the metatarsophalangeal joint, when the footwear is beingworn. In plan view, the stiffening component 308 tapers forward of the longitudinal midpoint of the ball region 114. In plan view, the stiffening component 308 tapers rearward of the longitudinal midpoint of the ball region 114. In other examples, at least some of the widest portion of the stiffening component may be positioned forward or rearward of a centre of the ball region 114. Such tapers may apply to other shapes of stiffening component, such as those described elsewhere herein. In other examples, the stiffening component 308 may not, in plan view, taper rearward of the longitudinal midpoint of the ball region 114. In other examples, the stiffening component 308 may not, in plan view, taper forward of the longitudinal midpoint of the ball region 114. For example, a stiffening component in the form of, in plan view, an elongate rectangle does not taper in a forward or rearward direction. A triangle with one of its sides extending across the ball region 114 at or adjacent to the middle of the ball region 114, may have, in plan view, a taper in the forward orthe rearward direction, depending upon the orientation of the vertex of the triangle opposite the side that is at or adjacent to the middle of the ball region 114. Referring to Figures 23 and 24, the stiffening component 308 is configured to be an interference fit within the recess 304. The edges of the stiffening component 308 engage corresponding respective edges of the of the recess 304. Since the sole 302 is formed from a flexible material, the stiffening component 308 may be made slightly larger than the recess 304. When the stiffening component 308 is pushed into the recess 304, the edges of the recess 304 are pushed slightly away, in plan view, by the edges of the stiffening component 308. This causes the edges of the recess 304 to grip the stiffening component 308, which helps hold it in place. The removable nature of the stiffening component 308 allows it to be replaced, without the need to replace the sole or the footwear. For example, a stiffening component may be replaced by a further stiffening component of greater or lesser stiffness, in order to provide bending control that is more appropriate for the wearer. The stiffening component may also be replaced if it is worn and / or damaged. In examples, the sole may include a slot or aperture into which the stiffening component may be slid to install it. Such a slot or aperture may, for example, extend generally parallel to an upper surface of the sole. For example, a rearward-extending slot may extend rearwards from a forward edge of the sole. For example, a sideward-extending slot may extend into a side edge of the sole. The stiffening component may be slid into the rearward-extending or sideward extending slot until it is in the appropriate position. In examples, the stiffening component is not removable from the sole 302. For example, the stiffening component may by bonded into or onto the sole, optionally including into a recess such as the recess 304. For example, the sole and the stiffening component may be co-moulded with each other. For example, one or the other of the sole and the stiffening component may be insert-moulded or over-moulded onto, into, or around the other. In use, the stiffening component 308 resists bending of the sole 302, and hence the footwear 100, 200, 300, 400, 500, around in the region of the metatarsophalangeal joint. This resistance may reduce plantarflexion, discourage toewalking, and / or encourage a healthy heel-toe gait. The longitudinally tapered regions may provide correspondingvariance of stiffness along a length of the stiffening component 308. In the illustrated example, the stiffening component 308 is longitudinally stiffest, and therefore most resistant to bending forces, at the point where it is laterally widest. Forward and rearward of the laterally widest point, the reducing width of the stiffening component causes a corresponding reduction in stiffness. Providing for gradually reducing stiffness in the forward and / or rearward direction of the stiffest region of the stiffening component may reduce or avoid abrupt discontinuities in stiffness along the length of the stiffening component, which may improve wearer comfort and / or improve therapeutic performance of the stiffening component. Longitudinal stiffness of the stiffening component may also be varied by changing a (vertical) thickness of the stiffening component along at least part of its length. For example, the thickness of the stiffening component may gradually reduce in a direction forward and / or rearward of the laterally widest point. Longitudinal stiffness of the stiffening component may also be varied by changing both the width (in plan view) and the (vertical) thickness of the stiffening component along at least part of its length. Longitudinal changes in width and thickness need not be consistent between the width and thickness. For example, the width may taper in a direction forward of the laterally widest point, but the thickness may, for example: be consistent along the length of the stiffening component; reduce in a direction forward of the laterally widest point, rearward of the laterally widest point, forward of a thickest point, and / or rearward of a thickest point; or increase in a direction forward of the laterally widest point, rearward of the laterally widest point, forward of a thickest point, and / or rearward of a thickest point. Longitudinal stiffness of the stiffening component may also be varied by varying material characteristics along the length of the stiffening component. For example, where layers of stiffer and less stiff materials are used, more (or relatively more, in cross-sectional area) of the stiffer material may be used around the ball region 114, with less (or relatively less, in cross-sectional area) of the stiffer material being used forward and / or rearward of the ball region 114. The overall size and / or shape (in plan view) of the stiffening component, the (vertical) thickness of the stiffening component, and / or the location of the stiffening component within the sole may be varied depending upon implementation requirements. In use, stiffening components as disclosed herein may provide additional stiffness around the region of the metatarsophalangeal joint. Such stiffening components may operate synergistically with other disclosed features, such as the reverse angle and / or the different compressibilities of various regions of the sole, to encourage healthy heel-to-toe gait motion, improve posture, discourage toe-walking, and / or encourage dorsiflexion. The reverse angle of the sole, and the stiffness provided by the stiffening component, may encourage the wearer to strike the ground heel-first when the wearer is in motion, and / or to keep the heel on the ground when standing. The disclosed stiffening components may optionally be used with textured insoles, such as the textured insole 184 described herein with reference to Figures 18 and 19. Where the stiffening component is removable, the comfort and / or therapeutic functions of the stiffening component may be altered to suit the wearer over time, and / or any particular situation in which the wearer intends to wear the footwear. For example, the use of stiffening components having different stiffness characteristics may enable the degree of plantarflexion and dorsiflexion to be altered, set, and / or reset over time, to allow for progressive correction. For example, the stiffness of the stiffening component may gradually be increased overtime, responsive to the wearer’s development and / or comfort-based compliance. For example, a stiffer stiffening component may be used when the wearer is at home, allowing the therapeutic functions of the stiffening component to be active over relatively long periods of time while the wearer is in a comfortable, familiar environment. A less stiff stiffening component may be used when the wearer is out of the home, where comfort may be more important than maximizing therapeutic effects. The ability to modify the stiffness of the stiffening component may increase the range of stretch compliance to meet individual needs relating to the degree of stretch severity and persistence of toe-walking. The ability to modify the stiffness of the stiffening component may reduce the risk of excessive stretching and / or potential injury from too early selection of an overly stiff stiffening component. In examples, the sole underneath and / or behind the heel region need not be less resiliently compressible than the sole underneath and / or forward of the ball region. For example, in any of the examples described herein, the sole underneath and / or behind the heel region may be more resiliently compressible than, or similarly compressible to, the sole underneath and / or forward of the ball region. When used with the stiffening component, such examples may provide at least some of the advantages described herein for other examples. The combination of the heel region being lower than the ball region and / orthe toe region, and the provision of the stiffened component, synergistically works to discourage toe-walking. In some examples, the stiffening component may reduce hypermobility, reduce toe-loading, improve proprioception, and / or shift the ground reaction force vector backward. Each of these factors, and any or all of the other functional components described herein, including in any combination, may inhibit and / or discourage toe-walking. For example, each of these factors and / or functional components, alone or in combination with any of the other factors or functional components, may inhibit or interrupt a negative compensatory pattern at a biomechanically critical moment: the toe-off phase. In some examples, the stiffening component may be configured limit excessive dorsiflexion at the metatarsophalangeal joints and / or attenuate premature heel off, thereby encouraging a more typical plantarflexion sequence during toe-off. Reducing premature forefoot loading and heel lift may help guide the wearer toward a full gait cycle including heel strike and controlled plantarflexion. In some examples, the stiffening component may reduce hypermobility in the forefoot by limiting excessive dorsiflexion moments at the MTP joints during late stance, without impeding natural toe-off. In some examples, the stiffening component may promote a sagittal-plane gait sequence. In some examples, such as those in which the stiffening component is recessed into the sole or is otherwise configured to not physically protrude from the sole, the product is relatively non-invasive from the wearer’s perspective. This may be valuable for wearer’s with sensory sensitivities, who may not tolerate bulky or visible interventions, and may also be positive from a compliance and aesthetic psychology standpoint, which may be important in paediatric rehab, for example. The shoes 100, 200, 300, 400, and 500 are intended primarily for indoor, or occasional outdoor, use. As such, the contact surfaces of the underside of the sole 102 are formed from a resilient foam material (excluding embodiments in which EPDM or other durable materials are employed, either across the full length of the shoe, or adjacent to the heel). In other embodiments, the contact surfaces of the underside of the sole 102 are formed from, or covered by, a durable material such as rubber, EPDM, or the like, in order to improve durability when the shoes are worn outside and / or on rough or abrasive surfaces. The footwear can take any suitable form, including, by way of non-limiting example, a training shoe, a running shoe, a sneaker, a shoe, a medical shoe, a device sandal, or slipper. The footwear can also take the form of corrective footwear that is specifically designed for neurodivergent individuals who have sensory issues. Embodiments of invention have been developed for use in the discouragement and / or correction of toe-walking in children and adolescents. In examples, the footwear may be particularly suitable for children with atypical gait patterns including idiopathic toe-walking. The human musculoskeletal system grows and develops considerably faster during childhood and adolescence. Embodiments of the invention may therefore be particularly beneficial to discourage and / or correct toe-walking in children and adolescents, before habits become established and undesirable changes to the neuromuscular system become more significant or potentially permanent. As one nonlimiting example, embodiments of the footwear can be designed for use until the foot stabilises in adulthood (typically in the late teens). However, older individuals may also benefit from the use of embodiments of the invention. Embodiments of invention have been developed for use in the discouragement and / or correction of toe-walking in neurodivergent individuals, including those having Autism Spectrum Disorder (ASD). Some neurodivergent individuals may be at greater risk of engaging in toe-walking. Some neurodivergent individuals may also find it challenging to resist engaging in toe-walking, or to break a toe-walking habit that has developed. Embodiments of the invention may therefore be particularly beneficial for discouraging and / or correcting toe-walking in neurodivergent individuals, and more particularly beneficial for individuals having ASD and / or other conditions having sensory symptoms. As one non-limiting example, embodiments of the footwear can be designed for neurodivergent individuals, optionally including individuals having ASD and / or another condition having sensory symptoms. However, embodiments of the invention may also be beneficial for neurotypical individuals. Embodiments of the invention may be particularly beneficial for neurodivergent children and adolescents, and even more particularly beneficial for children and adolescents having ASD and / or another condition having sensory symptoms. Embodiments of the invention may provide a gradual therapeutic stretch (and elongation) of the calf muscles. The angles and, preferably also pressures of the footwear, allow the wearer to gently stretch with every step and are supplementary to physiotherapeutic methods involving short-term stretches at steeper angles on, for example, triangular blocks. The angle between the foot and lower leg will typically be selected (or adjusted, where the shoe involves an adjustable element) to provide a level of stretch that is comfortable enough for everyday use. This increases compliance and reduces the risk of injury from overly aggressive stretching. The use of embodiments of the invention may reduce the chance of the wearer needing disruptive calf-muscle-lengthening surgery later in life, as well as reducing the risk of trips, falls, and rolling of ankle / foot. The use of embodiments of the invention may help correct the wearer’s posture, encouraging their body back into postural alignment. This may reduce the risk of back problems in later life, of which toe-walkers are at greater risk. The use of embodiments of the invention may help reduce anterior pelvic tilt, of which toe-walkers are at greater risk. Anterior pelvic tilt is the cause of many other postural issues. The disclosed footwear may provide a non-invasive, passive mechanical intervention for toe-walking. The disclosed footwear may reduce or avoid the need for braces or professional fittings. The disclosed footwear may encourage correct gait development through geometry and / or proprioceptive engagement. The disclosed footwear may maintain the appearance and usability of commercial children's footwear. The disclosed footwear may be scalable for mass production. The disclosed footwear may be adaptable for integration into different footwear size ranges, including different width fittings. The disclosed footwear may support modular therapy approaches adaptable to 5 different user needs and / or compliance levels. Although the invention has been described with reference to a number of specific embodiments, the skilled person will appreciate that the invention may be embodied in many other forms.

Claims

1. Toe-walking corrective footwear for discouraging toe-walking, the toe-walking corrective footwear comprising:a sole comprising an upper surface, the upper surface defining:a heel region for engaging a heel of a wearer’s foot;a ball region for engaging a ball of the wearer’s foot; anda toe region for engaging toes of the wearer’s foot; anda stiffening component that overlaps, in plan view, a region of the sole over which the metatarsophalangeal joint is, in use, positioned, the stiffening component extending rearward to at least a longitudinal midpoint of the ball region,wherein:the sole underneath and / or behind the heel region is less resiliently compressible than the sole underneath the ball region;material of the sole under the heel region is of, on average, higher density than material of the sole underneath the ball region; andthe sole is configured such that the heel region is lower than the ball region when the sole is resting on a level surface.

2. The toe-walking corrective footwear of claim 1, comprising:one or more nodules that extend downwards from the sole, the one or more nodules being configured to provide proprioceptive feedback to encourage muscle and tendon movement and stretch.

3. The toe-walking corrective footwear of claim 2, wherein:at least under the ball region, the one or more nodules comprise at least 50% of a total thickness of the sole, as measured from an upper surface to an underside of each nodule, the one or more nodules under the ball region being configured to discourage the wearerfrom tilting forward onto the toes in use.

4. The toe-walking corrective footwear of claim 2 or claim 3, wherein:at least one of the nodules that at least partly underlies the ball region has a greater volume than each of the other nodules.

5. The toe-walking corrective footwear of claim 4, wherein:exactly one of the nodules that at least partly underlies the ball region has a greater volume than each of the other nodules.

6. The toe-walking corrective footwear of any one of claims 2 to 5, wherein: the nodules comprise protruding spherical or semi-spherical nodules arranged along the lateral and medial margins from heel to toe, the nodules being configured to provide tactile feedback during gait.

7. The toe-walking corrective footwear of claim 6, wherein:the spherical nodules are constructed from a more rigid compound than adjacent sole areas.

8. The toe-walking corrective footwear of any preceding claim, wherein:a straight heel-ball line between the heel region and the ball region defines an angle of at least +5° degrees to the horizontal when the sole is resting on a level surface.

9. The toe-walking corrective footwear of claim 8, wherein the materials and configuration of the sole are such that the heel-ball line remains at a positive angle when the heel region and the ball region are compressed by the weight of a wearer standing stationary on level ground.

10. The toe-walking corrective footwear of any preceding claim, wherein;a straight ball-toe line between the ball region and the toe region defines an angle of at least +5° to the horizontal when the sole is resting on a level surface.

11. The toe-walking corrective footwear of claim 10, wherein the materials and configuration of the sole are such that the ball-toe line remains at a positive angle when the ball region and the toe region are compressed by the weight of a wearer standing stationary on level ground.

12. The toe-walking corrective footwear of claim 10 or claim 11 when dependent on claim 8 or claim 9, wherein the ball-toe line defines a greater angle to the horizontal than the angle defined by the heel-ball line, when the sole is resting on a level surface.

13. The toe-walking corrective footwear of any preceding claim, wherein the materials and configuration of the sole are selected such that the heel region of the sole compresses proportionally less than the ball region and / or the toe region, during ordinary walking employing a heel-toe gait.

14. The toe-walking corrective footwear of any preceding claim, wherein the sole comprises a foam material underneath at least the ball region.

15. The toe-walking corrective footwear of claim 14, wherein the sole comprises a foam material underneath at least the heel region, the foam underneath the heel region being of, on average, higher density than the foam underneath the ball region.

16. The toe-walking corrective footwear of any preceding claim, wherein the sole comprises a solid material underneath at least the heel region.

17. The toe-walking corrective footwear of any preceding claim, wherein the sole underneath and / or behind the heel region comprises a first material and the sole underneath and / or forward of the ball region comprises a second material different to the first material.

18. The toe-walking corrective footwear of claim 17, wherein the first material as ahigher Shore A hardness than the second material.

19. The toe-walking corrective footwear of any one of the preceding claims, wherein at least part of the stiffening component tapers, in plan view:forward of the longitudinal midpoint of the ball region; and / or rearward of the longitudinal midpoint of the ball region.

20. The toe-walking corrective footwear of any one of the preceding claims, wherein the stiffening component is removable.

21. The toe-walking corrective footwear of claim 20, wherein the sole comprises a recess for receiving the stiffening component.

22. The toe-walking corrective footwear of any preceding claim, comprising means for altering the degree of dorsiflexion of the wearer’s foot.5 23. The toe-walking corrective footwear of claim 22, wherein the means for altering thedegree of dorsiflexion comprises a strap configured to extend around an upper region of the wearer’s foot, adjacent to the wearer’s shin.

24. The toe-walking corrective footwear of claim 23, wherein the strap is adjustable to 10 allow adjustment of a pressure placed by the strap on the wearer’s foot, shin, and / or ankle, when the footwear is in use.

25. The footwear of any one of claims 22 to 24, wherein:the means for altering the degree of dorsiflexion comprises a cable configured to extend15 around a rear of the footwear adjacent to an Achilles tendon and / or calf of the wearer; and optionally, the cable is adjustable to allow adjustment of the pressure placed by the cable on the wearer’s foot, Achilles tendon, calf, or ankle, when the footwear is in use.

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