WO2008102189A1

WO2008102189A1 - Footwear with unstable sole structure

Info

Publication number: WO2008102189A1
Application number: PCT/HU2007/000063
Authority: WO
Inventors: László Solymosi; Beáta Karsch; Tibor Klein
Original assignee: Solymosi Laszlo; Karsch Beata; Tibor Klein
Priority date: 2007-02-23
Filing date: 2007-07-10
Publication date: 2008-08-28
Also published as: HU0700174D0; HUP0700174A2

Abstract

The object of the invention is footwear with unstable sole structure for restoring and/or maintaining statically optimal body posture and healthy walking and running dynamics, intended primarily for child users. The footwear comprises an upper and a sole structure attached to the upper, where the sole structure has a wearing layer designed to conform to the physiology of normal rolling gait, a roller sole (4) attached to the wearing layer, a support sole permanently attached to the roller sole (4), and a stiffener plate embedded in the support sole, with the roller sole and the support sole being made of thermoplastic plastic material. The invention is essentially characterised by that the wearing layer is implemented as a hollow body surrounding the sole structure, having a U-shaped cross-section and attached at its edges to the upper of the footwear, with a roller sole (4) designed to conform to the physiology of rolling gait and to cover the entire tread surface being fixed inside the wearing layer. A support sole designed to cover the entire tread surface is attached to the roller sole (4), the support sole comprising a support projection (9) adapted for preventing ankle pronation and dimensioned to at least match in size the print of the arch of the foot, with the material of the roller sole (4) being more resilient than that of the support sole.

Description

Footwear with unstable sole structure

The object of the invention is footwear with unstable sole structure for restoring and/or maintaining statically optimal body posture and healthy walking and running dynamics, primarily for child users, comprising an upper and a sole structure attached to the upper, where the sole structure has a wearing layer designed to conform to the physiology of normal rolling gait, a roller sole attached to the wearing layer, a support sole permanently attached to the roller sole, and a stiffener plate embedded in the support sole, with the roller sole and the support sole being made of thermoplastic plastic material.

There is a fundamental human need for bodily movement, including walking. However, the fulfilment of this need has become more and more removed from the natural environment with the advance of civilization. Walking barefoot on natural terrain members of previous generations were forced into "walking actively" by tracking and constantly adapting to irregularities of the ground, which caused muscles to be used (loaded) to a suitable extent. This sustained level of muscle load resulted in maintaining healthy circulation and sufficient levels of cell and tissue metabolism. The flat, artificial terrains of today's cities, combined with flat-soled trend-driven footwear and sedentary lifestyle often lead to the underuse of muscles and muscular dysfunction. Consequences include weakened muscles, ruptured muscle balance and the overloading of joints. An insufficient level of muscle load, prolonged over time, not only starts pathological processes in the motive apparatus but has an indirect negative influence on other apparatuses/organs. This is in the background of certain diseases of civilization unknown to members of previous generations. Ergonomically optimal gait can be achieved only by walking barefoot on uneven ground. It has long been recognised that optimal (barefoot) gait can be approximated by wearing footwear simulating unstable, uneven terrain. Wearing such footwear causes orientation sensor muscles (deep muscles) to become tensioned, which is indispensable for relieving joints and maintaining physiological body posture.

Patent description US 2003106171 discloses an article of footwear for changing the statical relations of the body and for simulating barefoot walking.

The article of footwear according to the invention has a sole attached to a shoe upper. A resilient cushioning insert is disposed in a cavity formed in the upper part of the sole, which produces a feeling of walking barefoot while wearing conventional footwear. The solution has the disadvantage that the relatively rigid conventional sole does not make possible the physiological "rolling" action of the foot during walking and therefore only partially elicits proper muscular activity. It is also a drawback that the shoe, the insert and the wearer's foot move separately (can be displaced relative to one another), which, apart from causing the shoe to wear prematurely, produces discomfort in the user. US patent no. 5 727 335 describes footwear for patients of osteoarthritis.

The inventive footwear comprises an upper and a sole structure attached thereto. The sole structure has a rolling layer consisting of a forward and backward portion arranged at an angle with respect to each other, an elastic and a supporting sole element. The configuration of the sole and heel facilitates walking and relieves load on the calcaneus. The solution has the drawback that the elastic sole element with the built-in pivot axis unevenly loads antagonistic muscles and therefore fails to restore muscle balance. A further disadvantage of the solution is - apart from the fact that the inventive footwear is rather complex - that the user has to "learn to walk" in it, has to seek and consciously maintain balance while walking.

The document with publication no. WO 01/15560 discloses footwear for

- dynamic rolling-walking action. The footwear has an upper for supporting the user's foot, to which is attached a sole structure adapted for producing the feeling of walking barefoot. To accomplish this the sole structure has a middle and a bottom layer. The middle layer is made of a relatively hard resilient material, while the bottom layer is made of softer resilient material. The bottom layer has arcuate segments producing an overall shape suitable for rolling gait. A shortcoming of the solution is that it fails to simulate walking on natural terrain adequately because of the pivot axis formed between the harder and the softer layer. Furthermore, the user has to maintain balance and ergonomically optimal body posture by continuous conscious effort ("walking awareness"). Patent description EP 0 999 764 describes a shoe designed for enabling rolling gait. According to the invention the sole structure attached to the shoe upper comprises a sole body and a covering (a wearing layer). A pivot axis is disposed in the wearing layer in the metatarsal area, about which the forward and backward portions may pivot. In the area between the centre of the foot and the heel a recess is formed between the sole body and the wearing layer, wherein a soft, resilient load distribution element is inserted. The shoe according to the invention is capable of providing natural rolling action of the foot during walking, with uniform load distribution. The disadvantage of the invention is that due to the fixed nature of the applied pivot axis it is only partially suitable for simulating a natural tread surface and thus for activating muscles in a near-natural way. A further disadvantage is that wearing the inventive shoe requires both training and constant attention on the part of the user. In case the wearer suffers from serious fallen arches s/he has to focus constantly on preventing ankle pronation (that could cause further impairment) while walking in the inventive shoes. If, such as in the case of small children, it is impossible to train the user for "aware walking", wearing the inventive shoes may cause further impairment. Consequently, child users or people with more serious health problems cannot use the inventive shoes without medical supervision. Known solutions include corrective insoles, particularly for children, and corrective heel modifications with the aim of preventing calcaneus and ankle pronation. Such a built-in insole is included in "Siesta" children's shoes produced by Sabaria Shoe Factory from the 1970's. The insole supports the arches of the foot, aiming at preventing ankle pronation. These prior art solutions provide passive support for the arches of the foot for producing a corrected joint position. However, this optimal position is maintained by the insole instead of active muscle work. This prevents muscles from strengthening and so they are unable to maintain optimal position without support. Thus this solution provides symptomatic rather than etiological (final) treatment. Also, these shoes are incapable of producing a feeling of instability and for maintaining proper muscle tone. The aim of our invention is to provide footwear for simulating unstable ground surface without requiring "walking awareness" from the user. The invention is primarily targeted for providing footwear for children whose muscles and joints have not yet been damaged and therefore are optimal subjects for prevention. Advantageous effects of the invention of course also apply for shoes intended for adolescents and adults. In these cases the aim is restoring healthy foot statics and walking dynamics for stopping pathological processes affecting the motive apparatus.

The invention is based on the recognition that, walking on the simulated unstable ground surface requires no conscious action ("walking awareness") on the part of the wearer if the bones of the foot are supported in a flexible manner.

A sole structure configured in this manner prevents ankle pronation while maintaining the stimulus necessary for active muscle work.

The inventive objective is realised by providing such footwear where the wearing layer is implemented as a hollow body surrounding the sole structure, having a U-shaped cross-section and attached at its edges to the upper of the footwear, with a roller sole designed to conform to the physiology of rolling gait and to cover the entire tread surface being fixed inside the wearing layer, and with a support sole designed to cover the entire tread surface being attached to the roller sole, where the support sole comprises a support projection adapted for preventing ankle pronation and dimensioned to at least match in size the print of the arch of the foot, with the material of the roller sole being more resilient than that of the support sole).

Prior art solutions for health-preserving or health-restoring footwear have sole structures designed to enable rolling gait. Sole structures enabling rolling gait have a curved tread surface instead of a rigid and substantially flat sole, with areas under the toes and the heel being slightly elevated from the ground. The degree of elevation is chosen such that during normal walking the sole portion under the talus is the first to touch the ground, and the portion under the toes leaves the ground last after a continuous rolling movement. This conforms to the physiology of walking barefoot. A sole structure configured conforming to the physiology of rolling gait is disclosed for instance in document EP 0 999 764. Because such a sole structure configured conforming to the pyhsiology of rolling gait is included in the prior art it will not be described in detail in the present document.

The footwear according to the invention has a sole structure comprising an inner lining and an upper attached to the sole structure. The upper may be made of materials conventionally applied in shoemaking industry such as leather, imitation leather, textile, or plastic. The upper may have the conventional configuration of a shoe, sports shoe, boot, or even sandal. Also, the material and configuration of the inner lining is identical to conventional solutions known in the art. In a preferred embodiment of the inventive footwear the sole structure is assembled from a wearing layer, a roller sole attached to the wearing layer, and a support sole covering the roller sole. The role of the wearing layer is to protect the underside of the sole structure from premature wear. According to the invention the wearing layer is implemented as a U-cross section hollow body that completely surrounds the sole structure from below and from the sides. The upper can be attached to the edges of the hollow body. In a preferred embodiment the wearing layer is made of resilient plastic or rubber providing good grip, the upper being attached thereto by means of welding, glueing, or a similar technology. Implementing the wearing layer as a hollow body has two major advantages. First, it increases the attachment surface between the wearing layer and the upper and thus may prevent the sole from coming off prematurely, and second, the wearing layer having the described configuration can protect the side surfaces of the roller sole and the support sole that are made of softer, resilient material from mechanical damage, thereby increasing shoe life.

The roller sole of the sole structure is laid into the wearing layer. The undersurface of the roller sole, contacting the wearing layer, is configured to conform to the physiology of rolling gait. The roller sole covers the entire tread surface, meaning that it extends from the rearmost point of the heel to the tip of the toes and has a width conforming to that of the sole of the foot. The roller sole is fixedly inserted into the wearing layer. According to a preferred embodiment of the invention the undersurface of the roller sole and the wearing layer are glued together. According to a further preferred embodiment of the invention the sides of the wearing layer and roller sole are not glued together, and therefore the two elements may move relative to each other. Such a configuration enables a small amount of relative displacement between the elements of the sole structure and the wearing layer, which significantly increases shoe life.

The roller sole is preferably made of thermoplastic plastic, particularly of soft, resilient polyurethane. The soft roller sole creates the feeling of walking barefoot on soft, uneven ground, thereby stimulating muscle activity. Feeling the uneven ground surface, which is needed to adapt to the continuously changing conditions provoked by the unstable sole structure, causes muscles to be tightened by reflex, which in turn relieves joints from load and helps maintain physiological body posture. Healthy walking or running dynamics is important not only for preventing joint or muscle ailments but has beneficial influence on the operation of other organs of the body. The prolonged activity of deep muscles, brought about by the unstable sole structure, enhances circulation and cell and tissue metabolism.

According to an essential feature of the invention a support sole covering the entire tread surface is permanently attached to the roller sole. The support sole may be attached to the roller sole by means of welding, glueing, or the like.

In the present description the term "tread surface" is used to refer to that surface of the sole structure on which the foot is supported. The tread surface can be defined as a plane figure bounded by curved lines, extending from the rearmost extremity of the ankle to the tip of the toes, having its largest width at the area where the bones of ball of the foot touch it. The foot is supported on the tread surface at the areas where the talus and the bones of the ball of the foot touch it, at the so-called anatomical support distance. Between these two areas the bones of the foot form an arch. The soft soles applied in conventional footwear with unstable sole structure may cause ankle pronation which can only be compensated by "aware walking", that is, by intentionally tilting the ankle outward. According to our invention a harder, relatively less resilient support sole is attached to the roller sole. The support sole comprises a support projection at least in the area under the arch of the foot. The support projection is adapted for preventing ankle pronation and thereby removes the requirement of mindful use. The addition of a relatively rigid support projection to the sole structure makes it unnecessary to "learn to walk again" in the inventive footwear with unstable sole structure and to focus constantly on keeping balance. Also, the support projection opens up the possibility of using the inventive footwear for small children who do not yet understand instructions. The support projection provides flexible support for the ankle joint while the muscle stimulus for keeping physiological body posture is also maintained. The support projection can fulfill its role if it at least matches in size the print of the arch of the foot. By "print of the arch of the foot" we mean the area where the surface of the sole of the foot does not touch the tread surface while the foot is supported (is resting) thereon.

According to a preferred embodiment of the invention the largest length of the support projection equals at least the anatomic support point distance of the tread surface, that is, the distance between support points on the thread surface of the calcaneus and the bones of the ball of the foot, and the largest width of the support projection extends at least from the medial edge of the sole structure to the midline thereof. The thickness of the support projection is chosen such that it can provide flexible support for the ankle. To achieve this, in the area under the support projection the roller sole should be thick enough to provide an "unstable environment" for the foot but should not be too thick in order not to lose the ankle-supporting effect. The largest thickness of the support projection should be preferably 60-80% of the largest thickness of the roller sole. In a preferred embodiment of the invention the largest thickness of the support projection is three-fourths of the largest thickness of the roller sole. The support projection is preferably made of the same material as the support sole. According to a further advantageous embodiment the support sole and the support projection form an integral element, but configurations where the support sole and the support projection are implemented as separate elements (made even of different material) secured permanently together, for instance by glueing, also fall into the scope of the invention.

In another preferred embodiment of the invention the support projection is connected with a smooth transition to the support sole at its end near the toes. Supporting the calcaneus by a conventional rigid sole makes walking an extremely painful experience for patients suffering from joint ailments, especially from arthritis. In a preferred embodiment the inventive sole structure comprises a support projection that is terminated in a cutoff at its end near the heel such that it does not cover the support point of the calcaneus on the thread surface. With such a configuration of the support projection the calcaneus touches the soft roller sole, while at the same time the advantageous effects of the invention are still provided for the user by the support projection. The cutoff may be bounded by plane or curved surfaces. According to a preferred embodiment of the invention the cutoff surface is bounded by a plane that is set at an angle of

18-30 ° with respect to the midline of the sole structure. According to a particularly advantageous embodiment the angle between the bounding plane of the cutoff and the midline of the sole structure is 21°.

According to the invention a stiffener plate is embedded in the support sole. The stiffener plate is made of a hard plastic material, such as PVC, or from a fibreglass reinforced plastic sheet. The role of the stiffener plate is to provide uniform load distribution. To accomplish this, the stiffener plate is dimensioned to at least match in size the print of the arch of the foot. According to a further preferred embodiment of the invention the stiffener plate terminates between the area where the bones of the ball of the foot contact the thread surface and the area where the toes contact the thread surface. Such a configuration of the stiffener plate provides uniform load distribution and load transfer to the sole structure without hampering the instability thereof. The stiffener plate is embedded in the support sole. The configuration where the stiffener plate is surrounded both from above and from below by the relatively softer support sole gives an especially pleasant feeling to the user, and provides a good simulation of walking barefoot. The stiffener plate is preferably made of a cellular material or from a perforated plate. As the material of the support sole penetrates into the holes in the plate, the stiffener plate gets firmly embedded and prevented from getting displaced with respect to other elements of the sole structure during use.

The invention will be explained in the following with reference to the attached drawings, where

Fig. 1 is the schematic top plan view of the inventive sole structure, partially broken out,

Fig. 2 shows a cross section taken in plane H-Il of Fig. 1 , Fig. 3 showing a cross section taken in plane Ill-Ill of Fig. 1 , Fig. 4 shows a cross section taken in plane IV-IV of Fig. 1 ,

Fig. 5 shows a cross section taken in plane V-V of Fig. 1 , and Fig. 6 shows a cross section taken in plane IV-IV of Fig. 4.

The schematic top plan view of the inventive sole structure is shown in Fig. 1. Figs. 4 and 5 show cross sectional views of the sole structure. The sole structure 1 is attached to the upper 2 of the footwear through wearing layer 3 having a U-shaped cross section. Inside the footwear the sole structure is lined with an inner lining 7. For the sake of clarity the inner lining 7 is only shown in Figs. 4 and 5.

Fig. 1 shows the schematic top view of the tread surface 8 of the sole structure 1 , not showing the wearing layer 3 and the inner lining 7. As the uppermost layer of the sole structure 1 (the support sole 5) is shown partly broken out, the configuration and location of the stiffener plate is clearly shown in the figure. The stiffener plate 6 is a PVC plate that has a plurality of holes and almost entirely covers the areas of the tread surface 8 supporting the heel and the middle of the foot, extending at the end near the toes until the area where the bones of the foot contact the tread surface 8. This choice of the length of the stiffener plate 6 is especially favourable because it preserves advantageous characteristics related to the unstable structure of the footwear sole. The thickness of the stiffener plate 6 is chosen such that the stiffener plate 6 is capable of receiving and uniformly distributing load. The upper and bottom surfaces of the stiffener plate 6 are implemented as smooth surfaces for securely supporting the foot. The support sole 5 completely surrounds the stiffener plate 6, and thus produces a comfortable feel while walking, preserving at the same time the unstable nature of the sole structure 1. During production the material of the support sole 5 fully penetrates the holes of the stiffener plate 6, and thereby the stiffener plate 6 gets fixed in the support sole 5 allowing no further displacement. Testing the footwear under real-life circumstances has showed that the invention's advantages are most fully realised if the thickness of the support sole 5 below and above the stiffener plate 6 equals the thickness of the stiffener plate 6 itself.

It is clearly shown in Fig. 3 in the cross-sectional views of the sole structure 1 taken in different planes that the wearing layer 3 is implemented such that its end portions towards the toes and the heel are elevated to a certain extent (in a manner known from prior art) conforming to the physiology of rolling gait. The wearing layer 3 completely surrounds the sole structure 1 from below and from the sides. The support sole 5, made of polyurethane, is dimensioned to cover the entire tread surface 8. As it is shown in Fig. 6, the support sole 5 comprises a downwards extending support projection 9 that at least matches in size the print of the arch of the foot. The support projection 9 is connected to the support sole along a plane, in which plane the cross-sectional shape of the support projection is a plane figure having longer sides touching the medial edge of the sole structure 11 and the midline 10 of the sole structure 1 , a first shorter side substantially perpendicular to the midline 10, and a second shorter side terminating in a cutoff 12. The line of the cutoff 12 is set at an angle of 21° with respect to the midline 10, the cutoff being located anterior to the support point of the calcaneus. The support sole 5 and support projection 9 provide flexible support to the foot while walking, with the heel being supported by the more resilient, softer roller sole 4. The support sole 5 and the roller sole 4 are glued together. The undersurface 13 of the roller sole 4, covering the entire tread surface 8, is glued to the wearing layer 8. The sides of the roller sole 4 and support sole 5 are not glued to the wearing layer 3 and therefore both the roller sole 4 and support sole 5 can move in a vertical direction with respect to the wearing layer 3. The roller sole 4 is made of a higher-resilience polyurethane compared to the support sole 5, which provides an unstable state for the foot, successfully simulating barefoot walking.

A further advantage of the inventive footwear is that it can be applied to prevent or alleviate diseases of civilization such as fallen arches, joint problems, spine disorders, varicose veins, etc.

List of reference numerals

1 sole structure

2 upper

3 wearing layer

4 roller sole

5 support sole

6 stiffener plate

7 inner lining

8 tread surface

9 support projection

10 midline

11 medial edge of sole structure

12 cutoff

13 undersurface

Claims

1. Footwear with unstable sole structure for restoring and/or maintaining statically optimal body posture and healthy walking and running dynamics, primarily for child users, comprising an upper and a sole structure attached to the upper, where the sole structure has a wearing layer designed to conform to the physiology of normal rolling gait, a roller sole attached to the wearing layer, a support sole permanently attached to the roller sole, and a stiffener plate embedded in the support sole, with the roller sole and the support sole being made of thermoplastic plastic material, characterised by that the wearing layer (3) is implemented as a hollow body surrounding the sole structure (1), having a U-shaped cross-section and attached at its edges to the upper (2) of the footwear, with a roller sole (4) designed to conform to the physiology of rolling gait and to cover the entire tread surface (8) being fixed inside the wearing layer (3), and with a support sole (5) designed to cover the entire tread surface (8) being attached to the roller sole (4), where the support sole (5) comprises a support projection (9) adapted for preventing ankle pronation and dimensioned to at least match in size the print of the arch of the foot, with the material of the roller sole (4) being more resilient than that of the support sole (5).

2. The footwear according to Claim 1 , characterised by that the largest length of the support projection (9) equals at least the anatomic support point distance of the tread surface (8), that is, the distance between support points on the thread surface (8) of the calcaneus and the bones of the ball of the foot, and the largest width of the support projection (9) extends at least from the medial edge of the sole structure (11) to the midline (10) thereof, with the largest thickness of the support projection (9) being 60-80%, preferably three-fourths, of the largest thickness of the roller sole (4).

3. The footwear according to Claims 1 or 2, characterised by that at its end near the toes the support projection (9) is connected with a smooth transition to the support sole (5) and the other end the support projection (9) is terminated in a cutoff (12) such that it does not cover the support point of the calcaneus on the thread surface (8).

4. The footwear according to Claim 3, characterised by that the angle (α) between the cutoff (12) and the midline (10) of the sole structure is 35°.

5. The footwear according to Claim 4, characterised by that the angle (α) between the cutoff (12) and the midline (10) of the sole structure is 21°.

6. The footwear according to Claim 1 , characterised by that the roller sole (4) and the support sole (5) is made of polyurethane.

7. The footwear according to Claim 1 , characterised by that the wearing layer (3) and the undersurface (13) of the roller sole are glued together.

8. The footwear according to Claim 1 , characterised by that the stiffener plate (6) at least matches in size the print of the arch of the foot.

9. The footwear according to Claim 8, characterised by that the stiffener plate (6) terminates between the area where the bones of the ball of the foot contact the thread surface (8) and the area where the toes contact the thread surface (8).