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This application relates to a midsole structure, especially for shoes. Today it is known the patent WO2006/010025 showing a midsole for walking shoes for Masai which has an essentially curved shape with convexity facing the ground and, in the heel area, an insert made of a polyester sponge or soft polyurethane foam whose hardness falls within 15 to 30. The convex shape of the midsole is indicated as a feature that can prevent malfunctions of the musculoskeletal system and maintain a correct posture of the spine.

This known solution presents some drawbacks, however: the insert being placed in the heel area and being made of soft material, it is found that, when rolling and thus during the phase in which the sole interacts with the ground during the walk, a feeling of instability for the user is generated due just to the softness of the insert, this being able however to cause soreness in the cervical and lumbar zone and the rear muscles of the lower limbs.

It is also known the patent US2009/0056165A1 which shows an improvement of the previous solution where in the heel zone is a seat is obtained by resiliently compressible elements: even this solution has the same drawbacks mentioned before.

It is also known the patent WO2009/061103, which shows an improvement in the previous solution wherein there are a front insert and a rear insert to be positioned at the rear of seats adjacent to a central projection protruding on the bottom: even this solution has drawbacks, as the same is made up of several components, which increase its structural complexity and therefore costs. It also does not allow to be changed to reflect the changing needs of the individual user, which may be subject to different pathologies.

Finally, this solution requires to create many combinations of components, each having different characteristics, according to a desired and specific pathology of the user, and so requiring to achieve industrially multiple types of footwear to meet the many needs of such individual users; also the number of embodiments further increases in that the same should be made for different sizes.

The main object of the invention is then to solve the technical problems identified, eliminating the drawbacks of the prior art referred to above, and then devising an invention that will lead to a midsole, particularly for footwear, which is structurally simple and composed of a limited number of components, the same allowing to be adjusted quickly and easily to the specific needs of the user in order to achieve a widely use although industrially a single product for each size is manufactured.

As part of the task above, another important object of the invention is to devise a midsole that forces the user to assume a constantly erect posture and, while walking, stresses the muscles throughout the body so as not to load only on the back muscles.

Another object of the invention is to devise a midsole wherein, during the rolling of the step, the foot, and in particular the area of the metatarsal, is not stressed during such movement.

Another object of the invention is to permit the activation of small muscles responsible for stabilizing the joints so that the muscular skeletal system provides the right posture for the user. Not the least object is to obtain a device having limited implementation costs and to be produced by conventional known plants.

The task and objects abovementioned, and others which will appear more clearly hereinafter, are achieved by a midsole structure, particularly for footwear comprising an arc-like surface with the convexity directed toward the ground, characterized in that on said surface there is, in the region between the tarsus and the metatarsus, a transverse seat for a semirigid support, which accommodates at least one elastically compressible insert that can be arranged removably thereat.

Additional features and advantages of the invention will appear clearer from the more detailed description of a particular but not exclusive embodiment, illustrated, for exemplary and not limiting purposes only, in the drawings attached, in which:

Fig. 1 illustrates, in exploded view, the structure of midsole that may be combined with an insole and an outsole;

Fig. 2 illustrates, in exploded and in a section view, the rigid insert and the support it is matched to;

Fig. 3 illustrates a three-quarters side view of the insert;

Fig. 4 illustrates a three-quarters side view of the support for the insert; Fig. 5 is a view made according to the section plane V - V of Figure 4;

Fig. 6 is a view made according to the section plane Vl - Vl of Figure 5; Fig. 7 illustrates an insert on a view from above;

Fig. 8 illustrates how the coupling between the insert and its support occurs;

Fig. 9 illustrates a side view of the midsole applied to a sole with the positioning that the foot takes on the same once the shoe is assembled;

Fig. 10 shows in various stages the rolling of the step;

Fig. 11 illustrates, in a schematic side view, how the pressure at the point of barycenter obligates to an always upright posture that in the moment of swing stresses the muscles of all the body so as not to load only the back muscles;

Figs. 12-13 illustrate respectively a side and front view of a schematic view of the lower limbs of the pelvis. In the embodiments that follow individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other examples. It is also worth noting that everything in the procedure of obtaining the patent proves to be already known is supposed not to be claimed and subject to drop (disclaimer) from the claims.

With reference to the figures mentioned above, it is identified by the number (1) a midsole structure, especially for shoes, not shown, which may include an insole (2), advantageously of ergonomic type, and a sole (3), which can be made of rubber or other plastics. The structure of the midsole (1) is made of plastic and should allow to distribute the weight-load of the foot charged on it at least on the area (4) of the plantar arc, the same structure thus being feasible in a semi-rigid plastic .

The structure of midsole (1), and consequently the possible sole (3), respectively have a surface (5a, 5b) having a curved shape, with convexity facing the ground. At the surface (5a) of the midsole structure (1) there is obtained, in the area (4) of the metatarsal, a seat (6) which extends, transversely, the whole structure of midsole (1). At said seat (6) is positioned, integrally therewith, a support (7) for an insert

(8), elastically compressible, removably positioned therein. The support (7) of insert (8) are thus placed in a fixed position at the meeting point of the tarsal and metatarsal in the zone (4) of the plantar arc and thus in a zone of the barycenter of the user's foot (9). The support (7) has a central body (10) presenting an approximately elliptical shape in cross-section, and a length approximately equal to that of the seat (6). At the ends of the central body (10) are associated and project radially a pair of appendixes (11a, 11b) which are positioned at the side surfaces (12) of the midsole structure (1). The support (7) is therefore associated fixedly to the seat (6) and to the structure of midsole (1), the same being made of semi-rigid plastics to adapt, during the rolling of the foot, to the shape which the structure of midsole (1) takes. The central body (10) then presents an axial cavity (13) which is seat for the movable insertion of the insert (8). The latter is counter-shaped to the cavity (13) and is elastically deformable but yet stiff enough to create a center of pressure toward the plantar arc: the stiffness of the elastically deformable insert (8) must be such as to determine a sense of instability to the user, as shown in Figure 11 , such as if the user was standing resting the plantar arch area, and then the center of gravity of the foot, on a stick with a round section that acts as an element which the foot uses as fulcrum.

In this way the body, especially the muscles of the trunk, are induced instinctively to get going to constantly seek a balance of the body itself, causing a work for these muscles that usually are not in use. During the rolling of the step, illustrated in Fig. 10, an approximately constant zone (14) gets to be defined wherein the surface (5a) or surface (5b) are interacting with the ground: in the intermediate condition, in which the area (14) approximately finds correspondence with the area (4) of the plantar arc, all the weight of the body pivots on the barycenter passing just through the area (4) of the planar arc: the pressure of body-weight made at the point of barycenter obliges a more upright posture and therefore in the moment of swing stresses the muscles of all the body so as not to load only the back muscles. During the rolling of the step the insert (8) being elastically compressible absorbs the various pressures that stress the foot at the point of barycenter and, thus, the area (4) of the metatarsal is not stressed by the movement.

The interchangeability of the insert (8), which as said functions to restrict the semi-rigidity of support (7), allows to customize the structure of the midsole

(1) according to the weight of the user. Conveniently the midsole structure (1) presents means for removable interconnection of the insert (8) to the support (7), these means being constituted by a plurality of plugs (15) protruding inside the cavity (13) of the support (7), which interact with counter-shaped recesses (16) obtained at the surface (17) of the insert (8) placed within the cavity (13). Such plugs (15) and recesses (16) can be placed in one or more points, may be in desired number and may present the most suitable conformation.

In the particular embodiment outlined the plugs (15) are obtained both longitudinally and transversely to the central body (10) at its surface defining the cavity (13), said plugs having, in section, a rectangular and trapezoidal shape. In correspondence of the latter there is obtained a groove (18) on which a counter- shaped protrusion can removeably insist (19) obtained at the respective recess (16) present on the insert (8).

It has been found that in practice the invention has achieved the aforementioned tasks and objects, there having been obtained a structure of midsole which is structurally simple, consisting of only three components, the replacement of the insert according to the user weight allowing the user to adapt the structure of midsole quickly and easily according to specific user needs in order to find a widely use although industrially a single product for each size and only a multiplicity of inserts of varying stiffness or elasticity should be made.

It has also been made a midsole that forces the user to assume a constant upright posture and, at the time of walking, stresse the muscles of all the body so as not to load only the back muscles, and also during the rolling of step, the foot, and in particular the area of the metatarsal, is not stressed during such movement. Finally, the structure of midsole allows activation of the small muscles responsible for stabilizing the joints so that the muscular skeletal system provide the right posture for the user, the same presenting limited costs of production, storage and transport content. The used materials and the dimensions constituting the individual components of the invention may be more pertinent according to specific needs. The various means to make certain different functions need not certainly coexist only in the embodiment shown but may themselves be present in many embodiments, although not shown.

The characteristics indicated as advantageous, suitable or similar, may also be missing or be replaced by equivalents.