GB2583705A

GB2583705A - Resilient footwear with trampoline and pole vault effects

Info

Publication number: GB2583705A
Application number: GB1905635.7A
Authority: GB
Inventors: Hartveld Adri
Original assignee: Healus Ltd
Current assignee: Healus Ltd
Priority date: 2019-04-23
Filing date: 2019-04-23
Publication date: 2020-11-11
Anticipated expiration: 2039-04-23
Also published as: GB202005661D0; GB201905635D0; WO2020217041A1; GB2583705B; GB2584955A

Abstract

A shoe sole 3 having a reinforced plate 6 comprising fibrous material. The plate resides between the calcaneus 20 and metatarsal 22, 23, 24, 25, 26 bones or the rear and middle of the foot 4 of the wearer. The plate is sandwiched between the wearer and above a compressible portion 7 which is adjacent to the ground 5. The plate comprises at least one groove (13 & 14 fig 3). Outer sole 8 portions may reside underneath the compressible portion such to engage and grip the ground which may be separated by a recess (18, fig 5a).

Description

Resilient footwear with trampoline and pole vault effects

(Background)

The present invention relates to a shoe sole and particularly to a sole as part of footwear for use in connection with dynamic activities which involve fast walking, running and jumping. The sole is designed to reduce excessive strains on the body that result from high impact forces, lateral twists and excessive vibration. The unique construction of the compliant sole and the plate, attached to it at the top of the sole, reduces the forces during landing of the foot and facilitates recoil for upwards and forwards movement of the body. By utilizing the elastic characteristics of a trampoline and of a bamboo pole vault, it results in superior shock absorption and energy return without vibration.

Walking and running on hard roads and uneven and potentially slippery ground requires a shoe sole that protects the sole of the foot. This shoe sole also needs to protect the body against sliding, against sudden high impact forces on the body and against acute sharp indenting into the foot. The shoe sole needs to be lightweight and must not hinder the normal and natural movement of the feet, ankles, knees and hips.

When running or jumping, the human body experiences a sudden increase in vertical ground reaction force at the time that the foot comes into contact with the ground. This rapid force is commonly termed shock or impact loading. The repeated application of such forces to the human body during running or jumping activities is a major contributor to musculoskeletal injuries. The repeated high loads can cause the breakdown of components of the musculoskeletal systems: joints, ligaments, tendons, muscles and bones.

During walking, running and jumping activities, the shock on the body is reduced when the time between the outer sole of the shoe contacting the ground and the foot bones coming to a standstill is increased. In conventional sports shoes this time can be very brief as the midsole and outer sole parts that are situated between the tuber calcanei (heel bone) and the ground, and the sole parts that are situated between the fifth metatarsal head and the ground, are typically of limited thickness, continuous and made of medium and high density rubber and foam materials. The weight of such soles as well as the resistance to the normal roll of the foot reduces the efficiency of walking and running. The sole materials are typically made out of viscoelastic materials. Therefore, during walking, running and jumping, such shoe soles will attenuate energy, that is not returned to the body. This means that the sole does not push the person upwards and forwards during the second part of the stance phase during walking and running. The weight of conventional sport shoes, the resistance to the roll of the foot and the lack of elasticity of the materials of the soles all contribute to a reduction of energy efficiency during walking and running.

During walking and running activities in conventional shoes the wearer could inadvertently step on a stone. This could give a sudden high increase in lateral ground reaction forces on the body and therefore cause a strain injury on the wearer of the conventional shoe.

Elastic composites with variable properties have been around for centuries. Throughout history artisans and craftsmen have exploited the diverse properties of materials as they mastered skilful techniques to combine and convert raw materials into objects of consumption. However in modern times, in the footwear industry fabrication methods have mainly focused on fashion. The construction of shoes has, at best, not given optimal protection, and often has hindered the wearer's feet as well as his walking, running and jumping.

Footwear with various aspects of a trampoline effect has been invented by Randy Lopez in 1996 (US5680714A), by Martyn Shorten & Joseph Skaja in 1997 (W01999022160A1) , by Karl Muller in 1999 (US 6782639), by Pamela Greene & David Jones in 2003 (US7013581B2) and by Ryan Ringholz & Hung-Chia Lin in 2016 (W02017147490A1). None of these inventions use a fibre reinforced plate to increase the energy return and reduce the weight of the sole.

In nature, since creation, natural fibres provide shock absorption and energy return to protect and propel animals. For example a monkey uses tree branches to swing from tree to tree. Biomimicry has been used in ankle foot orthoses to enhance the spring control such as the device invented by Hugh Herr, Joaquin Blaya & Gill Pratt in 2011 (US8287477B1). However no previous inventions have combined trampoline like mechanics with the spring like characteristics of a curved plate or beam in a shoe sole.

The invention will now be described solely by way of example. Features of the invention are described in relation to embodiments of the present invention described with reference to the accompanying drawings in which: Figure 1 shows a cross section of the shoe from a lateral view with three bones of the wearer's foot. The shoe touches the ground whilst minimal weight is applied to the sole, as at the very start of the stance phase of running.

Figure 2 shows the same cross section of the footwear as Figure 1. A high downwards force is applied to the sole, which results in full compression of the sole, as during the middle of the stance phase of running.

Figure 3 is a top plan view of the grooved sole plate with markings to show the location of the weight bearing skeletal structures of the wearer's foot in relation to the plate.

Figure 4 represents a rear view of the shoe and the wearer's left lower leg during the 4 stages of the stance phase of fast running: a, b, c & d.

Figures 5 a, b, c & d show a cross section of the shoe and the wearer's foot from a rear view, at the level of the five metatarsal heads. As in Figure 4, 5a, 5b, 5c and 5d represent the sole and the foot during the 4 stages of the stance phase of fast running.

Figure 6 shows a cross section of the shoe across seven bones of the wearer's foot, from a medial view, when the shoe is resting on ground 5, but no weight is applied on to the sole.

Figure 7 shows the cross section as in Figure 6 when the sole is semi-compressed as it would be at a time during the fourth quarter of the stance phase of running.

Figure 8 shows the cross section of the shoe as in Figure 6. The sole is only compressed at the tip of the shoe as it would be at the end of the stance phase of running and jumping.

According to the present invention there is provided a shoe generally designated 1. The shoe comprises of an upper part 2 within which a wearer's foot 4 is received, and a sole generally designated 3. The sole is conventionally located on the underside of the upper part 2 such that, in use, it is orientated between the wearer's foot 4 and the ground 5. The sole has a sole arrangement, which includes a hard semi rigid reinforced plate 6 situated on top a compressible portion 7, also referred to as midsole, and a bottom sole portion 8, also referred to as outer sole. The outer sole 8, in use, is ground engaging and as such may be configured appropriately to impart the required grip properties with the ground 5.

The mid sole 7 may be of uniform mechanical properties, for example density, over its entire extent. Alternatively, the midsole 7 may be configured so as to have differing mechanical properties over its extent. This compressible portion 7 and the outer sole section 8 may have various shapes with recesses to provide a trampoline effect during running, fast walking and jumping. Various shapes of these sole sections may result in the provision of pivots 9, 10 and 11 as illustrated in Figure 1, 2, 3, 6 and 7 with arrows. Pole vault effects are provided through the construction of the plate as featured in Figure 3, in combination with various shapes of the midsole 7 and outer sole 8, creating pivots to bring about the energy return from the shoe sole.

Figure 3 illustrates the location of the high pressure areas 16: under the tuber calcanei, and 17: under the metatarsal heads. The high rigidity of the sole member protects the foot against high pressure on the wearer: underneath the cuboid bone 21, the navicular bone 33, the cuneiform bones 34 and the metatarsal bones 22, 23, 24, 25 and 26 of the foot, as drawn in Figure 1, 2, 6, 7 and 8.

In embodiments of the present invention, the fibre reinforced plate 6 acts as a beam to support the longitudinal arch of the foot between the calcaneus 20, the cuboid bone 21 and the metatarsal bones 22, 23, 24, 25 and 26 of the wearer. It needs to be rigid in this area, and therefore a groove 13 or multiple grooves 13 and 14 run longitudinally. This ensures that the plate gives a greater resistance to stress during brisk walking, running and jumping. As with a bamboo pole and with pole vaulting the highest stresses occur on the outside of the bent beam. As with a pole, within the middle zone of the pole or groove there are minimum or no stresses at all. Therefore there is no need to put a high density material inside the groove. As bamboo, that is a naturally hollow material, the plate is much lighter per unit length than a solid flat plate, yet it resists greater stresses. Given that pole-vaulting essentially involves the conversion of the kinetic energy of the running athlete to the potential energy of the jump using strain energy stored in the pole (the energy stored in elastic deformation), a lighter pole enables an athlete to run faster. In the same way the plate in the footwear according to the present invention, provides little resistance to running, but more energy return. In its elastic recovery, the plate is sufficiently strong and flexible to allow substantial amounts of energy to be transformed into elastic strain energy stored in the deformed plate.

The grooves in the present invention also allow the foot to roll how it needs to roll for shock absorption and propulsion. Because they are positioned longitudinally in the plate at the level above the distal part of the calcaneus, the navicular bone, the cuboid, the cuneiform bones and the metatarsal bones, pronation of the foot is not impeded. This ensures a normal roll of the foot during walking, running, as in Figure 4, and jumping. This specific localised rigidity and flexibility of the plate is a result of a combination of fibre orientation and the singular or multiple grooves, which run from proximal to distal.

As illustrated in Figure 2, during faster running, when the midsole is fully compressed in this area the deepest point of the groove(s) could come to a standstill whilst the calcaneus 20 and the head of metatarsal bone 22 continue to move in a downwards direction. Therefore the plate could provide a further deceleration to the calcaneus and metatarsal bones. Once the calcaneus and metatarsal bones reach their lowest point the plate is at its most stressed. Very shortly after that point of time, through its elasticity, the upper sole member will provide an additional force to assist the body in the upwards and forwards direction away from the ground surface through upwards pressure on the calcaneus and heads of the metatarsal bones, as illustrated in Figure 7. The plate with its fibres, such as flax fibres, is attached at the edges to a compliant but robust sole material, such as polyurethane, that is ground engaged. This can be compared to a trampoline where the springs at the outside provide the shock absorption and kinetic energy return.

In an embodiment of the present invention the rigid sole member 6 is constructed as such that the plate like structure is curved with the ground facing side being convex, especially at the level of the grooves 13 and 14 as illustrated in Figure 3. In order to provide an effective trampoline and pole vault effect the plate with its composite fibre reinforced layers has an overall high rigidity. The flexular rigidity is particularly high both in the anterior-posterior direction directly below the calcaneus 20, cuboid 21 and metatarsal bones 22, 23, 24, 25 and 26, and in the lateral-medial direction directly below the calcaneus 20. This bending resistance is the result of a combination of fibre reinforcement and the curving of the plate through its cupping 15 and single or multiple grooves 13 and 14.

Striking the foot, as such that the fifth metatarsal head 27 is the first bony point of the human body that has force applied from the ground, is the most effective way to run fast, as is picture in Figure 4a&b and Figure 5a&b. It is also the most efficient way of landing and jumping. Whilst the musculoskeletal system works best in this way, the sole could enhance the effectiveness with the right design, protecting the body.

In an embodiment of the present invention there may be provided a substantially inflexible portion to the rigid member in the area below the calcaneus 20, cuboid bone 21 and fifth metatarsal bone 22, whilst the remainder of the rigid member 6 is less rigid. This would be to permit a desired degree of transverse and rotational flexibility so as to allow pronation of the ankle and foot, as is illustrated in Figure 4 a, b, c and d, and flexion of the metatarsal phalangeal joints, as is illustrated in Figure 6 and 7. The areas of differing rigidity may be provided as a result of the construction of the plate member 6. For example, three grooves in the rigid member 6 may be manufactured through compression moulding of fibre reinforced composites.

The mid sole 7 is manufactured from a compressible material, such as low density polyurethane foam. The rigid member 6 is manufactured from a substantially incompressible composite. Preferably, this composite has a ShoreA hardness value of greater than 90. The material of the rigid member may comprise a polymer such as an organic fibre reinforced composite, for example flax fibre reinforced thermoplastics. The combined materials and construction of the sole 3, preferably provides a sole which is able to compress to 10% to 90% of its original thickness, when subjected to the application of a compressive force in the region of 1000 to 6000 Newton.

As illustrated in Figure 4 a and b, in use, when striking the foot during running, the immediate shock is dissipated across the rigid member 6, which results in a lower initial force under the foot compared to that experienced with conventional running shoes. Due to the natural build of the foot, the body weight impacts on the calcaneus 20 and the fifth metatarsal head 27 during walking and running. The shape and rigidity of the sole member 6 ensures that the force ground reaction force transmitted from the ground 5 does not cause unnatural and excessive pressure on the area of the longitudinal arch of the foot, including cuboid bone 21. The shape of the rigid sole member 6 is as such that it has a groove 13 or multiple grooves 13 and 14, which are convex from the side of the ground 5.

According to a further embodiment of the present invention, in combination with other features of this invention, as shown in Figure 4a,b,c&d and Figure 5a,b,c&d, there is provided a small recess 18 directly under the fifth metatarsal head 27 of the wearer. This recess, between two strands of outer soling, allows the fibre reinforced plate 6 and midsole 7 above the recess to absorb the impact from the foot strike when the wearer lands on this area of the foot. The fifth metatarsal head 27 of the wearer 4, and therefore the entire human body, will be decelerated over a considerable distance by the fibre reinforced plate and the compliant low density midsole material that are situated directly underneath. As in a trampoline, the material in this area will also give energy return when the force on this area reduces, later in the stance phase of the step during the run, or later during the jump.

According to a further embodiment of the present invention there is provided a shoe 1 in a "heel-less" configuration, which is to say that a recess 12 is provided in the sole in the region below the posterior portion of calcaneus or heel bone 20 of the wearer's foot 4. A rear pivot 9 is provided through the shape of the outer and midsole below the fibre-reinforced plate. Because there is a recess 12 directly below the tuber calcanei of the wearer, there is energy return after the downwards movement of the calcaneus during running, walking and jumping. The resilient and compliant sole part below the plate is compressed and springs back into its original shape when the pressure on the calcaneus is reduced. This transverse energy return is a similar mechanism as a trampoline with springs around the canvas on which the user jumps. On impact the fibre reinforced plate 6 is also stretched in the longitudinal direction through pivot 9, and springs back when the pressure on the calcaneus is reduced. Therefore it also provides a similar mechanics as a pole vault.

In an alternative embodiment, the shoe sole 3 may be provided with a heel, and provide a pole vault effect or a trampoline effect with varying densities across the sole.

In another embodiment of the present invention, the rigid member 6 may extend to only just anterior to the metatarsal heads 27, 28, 29, 30 and 31.

In an embodiment of the present invention, during fast running, the deepest point of the plate member 6 could come to a standstill whilst the calcaneus 20 and the heads of metatarsal bones 27, 28, 29, 30 and 31 continue to move in a downwards direction. This is illustrated in Figures 5, 6 and 7. The high ground reaction forces result in a slight bending of the sole plate. During this point of the stance phase during running the mid sole 7 is fully compressed in this area. Therefore the upper sole member 6 provides a further deceleration to the calcaneus 20. Once the calcaneus 20 and the metatarsal heads 27, 28, 29, 30 and 31 reach their lowest point the sole plate 6 is at its most stressed. Immediately after that point of time, through its elasticity, the plate 6 will provide an additional force to assist the body in the upwards and forwards direction away from the ground surface through upwards pressure on the calcaneus 20 and heads of the metatarsal heads 27, 28, 29, 30 and 31.

In various embodiments of the present invention the greater height of the low density mid sole 7, as a result of the considerable thickness under the tuber calcanei 20 and under the metatarsal heads, is also highly advantageous. The mid sole 6 may be configured so as to compress to a close to flat configuration in parts of the sole. An example of localised flattening of the sole is shown in Figure 4b, during running, with the centre of pressure from the runner under the metatarsal heads 27 and 28, as shown in Figures 5a, b and c. The high nature of the mid sole 7 ensures that both the first bony parts to come into contact with the ground are supported at a greater height off the ground 5 at the very start of a foot strike, in comparison to conventional running shoes. Therefore the body is decelerated over a greater distance during the first parts of the stance phase, as is illustrated in Figure 4a,b&c and Figures 5a,b&c. This results in a less rapid increase in vertical ground reaction force experienced by the wearer 4. The lowering of such impact forces reduces the risk of injury.

In an embodiment of the present invention there is provided a sole arrangement, including a plate member 6 and a compressible portion 7 that, in use, has a total sole height of between 25 and 40 mm between the calcaneus and the ground and a total sole height of between 15 and 35 mm between the metatarsal heads and the ground, when little to no weight or pressure is applied to the sole. In any embodiment of the present invention such heights are variable dependent on the shoe size and the use of the footwear. For example in one embodiment of the present invention, for a shoe size UK 9 / EU 43, there is no differential in these two heights, with the sole height being 30 mm both rear and front. In another embodiment, for a shoe size UK 9 / EU 43 there is a 10mm differential with 35mm between the calcaneus and the ground, whilst there is 25mm between the metatarsal heads and the ground.

According to another embodiment of the present invention, in combination with some of the previous features, there is provided a pivot in the area directly below the first and second metatarsal heads 31 and 32 of the wearer, as is illustrated with dotted line 10 in Figure 1, 2, 3, 6 and 7. This pivot is the result of a difference in sole height between the area directly below the metatarsal heads 30 and 31 and the area directly below the distal phalange 38 of the second and first toes. Due to this difference in sole thickness, and the upwards curve of plate member 6, there is a gap between the front of the shoe and the ground during the first stages of the stance phase. In one such embodiment of the present invention there is 15-20mm greater height below the metatarsal heads than below the distal phalange. In another such embodiment there is 10-15mm greater height. In another such embodiment there is 5-10mm difference. As illustrated in Figure 1, 6 and 7 the grooved plate member 6 supports the foot at the rear of this pivot and tilts forwards when the centre of pressure from the body weight moves ahead of the pivot line 10. The weight of the body stressing the grooved plate as a beam like structure has a similar mechanism as a pole vaulting athlete leaning on a pole vault at the first part of the pole vault action. After the maximum stress on the plate, energy from the plate is released and assists the wearer 4 to move upwards and forwards. The up and forward acceleration is also assisted by the push off of the metatarsal heads 25 and 26 against the plate 6 when the plate has tilted over the pivot 10. This then has a similar mechanism as a sprinter starting his running race pushing off against a starting block.

In various embodiments of the present invention, in use, when the shoe is resting on ground 5, but no weight is applied on to the sole, as illustrated in Figure 6; there is a space between the bottom of the sole directly below the first distal phalange 38 and the ground 5, that is greater than 14 mm for a shoe of shoe size UK 9 / EU43. In an embodiment of the present invention this dimension is 16 -18 mm. In another embodiment this dimension is 18 -20 mm. In another embodiment it is greater than 20mm.

In various embodiments of the present invention a third pivot 11 is provided as illustrated in Figure 3, 6, 7 and 8. At the very end of the stance phase of running and walking the wearer 4 can give an extra flick forward pushing back on plate member 6 to assist the forward propulsion of the body.

According to another embodiment of the present invention there is provided an insert for a sports shoe, the insert being adapted to lie, in use, between a compressible portion of the sole arrangement of a sports shoe and the foot of a wearer of the shoe, the insert including a rigid portion, in use, is shaped so as to lie beneath the heel bone 20, cuboid bone 21 and the fifth metatarsal 22 of the wearer. The rigid portion may fully comprise the insert. Alternatively, the rigid portion may be incorporated into the insert such that portions of the insert extend beyond the bounds of the rigid portion.

In an alternative embodiment of the present invention the relatively rigid sole member is a plate like structure with a marked curvature which is convex on the ground facing side. In this embodiment there is only a thin sole part which is made of compressible material and therefore the rigid sole member provides all or almost all of the footwear's shock absorption and energy return.

Claims

CLAIMSClaim 1.There is provided a shoe sole with a sole arrangement that includes a strong fibre reinforced plate situated on top a compressible portion of a considerable thickness, where, in use, the plate is provided between the compressible portion and the calcaneus, cuboid and metatarsal bones of the wearer foot of the wearer, with the plate containing a groove or multiple grooves, positioned longitudinally, running from directly underneath the distal part of the calcaneus and the navicular bone to directly underneath the cuneiform bones and the metatarsal bones, with specific localised rigidity and flexibility of the plate as a result of a combination of fibre orientation and the singular or multiple grooves, and in which the groove or multiple grooves are convex ground facing.