Background of the Invention

The invention relates to footwear according to the preamble of claim 1, the footwear comprising a sole and the sole comprising a formation, the said footwear being used for sports that take place in water. The invention also relates to a base for water sports according to the preamble of claim 7, arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water. The invention furthermore relates to an arrangement for water sports according to the preamble of claim 18.

The invention relates to equipment used in water sports, especially footwear used in water sports and a base with which the footwear comes into contact.

There are many ways for moving in water, for instance in a swimming pool or in natural water. The most common ways of moving are probably swimming or diving, but nowadays it is also increasingly common to walk or run in water. In water walking, one proceeds in the water in a standing position by making walking movements, and in water running the movement forward takes place in a standing position by making running movements. Most often, a float attached to the waist is used as an aid. When using a float, the feet of the athlete are not supposed to touch the bottom, meaning that the movement takes place in water that is deeper than the height of the person doing the exercise. Water walking or running may of course also be practiced in shallower waters, in which case the feet of the athlete reach the bottom and he is able to kick for more speed from the bottom and move forward in similar way as during walking or running.

In water, especially in a pool, it is possible to walk by kicking the bottom for speed up to a certain point without using additional equipment. In order to increase the speed, one needs to lean forward in the water in a manner similar to running on land. As the forward lean of the athlete becomes great enough, it is no more possible to gain more speed by kicking the bottom because of the buoyancy of the water and especially because of the slipperiness of the pool bottom. As the athlete leans forward, the buoyancy of the water and the slipperiness of the bottom cause friction to diminish between the soles of his feet and the pool bottom, making it more difficult to take advantage of the pushing force against the bottom of the pool that he uses for moving forward. As the forward lean of the athlete increases, friction between the soles of the feet and the pool bottom is diminished, finally making it impossible to push against the pool bottom.

Different devices used in sports that take place in water are known. These include for instance fins that are put into the athlete's feet and that help to gain more kicking force for swimming and especially for diving. In is difficult to walk forward wearing a fin, since the long front portion of the fin easily folds under the foot. The same happens if one tries to run while wearing fins.

From JP 2000217601, swimming footwear is known that has a slip preventing function. This slip preventing function comprises a bumpy mat arranged in the sole under the ball of the foot and the heel, which causes friction between the pool bottom and the footwear and thus makes slipping less likely. In another embodiment disclosed in the citation, the bumpy mat has been arranged to cover the entire area of the footwear.

From JP 2003052403 projections that extend in an amoeba-like manner are known, the projections being located in the soles of shoes, in gloves or other applications. As a special embodiment, reference is in the publication made to footwear used in the pool or when walking on the edge of a pool. These projections that extend in an amoeba-like manner are intended to prevent slipping by increasing the roughness and unevenness of the surface and thus friction resistance.

The disadvantage of the footwear for water sports known from the above- presented citations is that in addition to preventing slipping, they have no effect on the fact that as the athlete leans forward into the direction of the motion, the slipperiness of the bottom and the buoyancy of the water result in the speed and movement being slowed down as the pushing foot slips backwards along the pool bottom. The bottom of the pool is usually slippery and the buoyancy of the water tends to lift the athlete towards the surface. The forward lean of the athlete increases and the effect of the buoyancy becomes more pronounced until the forward lean is steep enough and pushing against the bottom becomes impossible, at which moment the movement stops.

Brief Description of the Invention

The object of the invention is to solve the above-mentioned problems. The object of the invention is enable the movement of the athlete in the water in such a way that the athlete can proceed in a steeply forward-leaning position, kicking the bottom for more speed, without the slipperiness of the pool bottom and the buoyancy of the water essentially slowing down the movement. The object of the invention is achieved by the footwear for water sports according to claim 1.

The invention also relates to a base for water sports according to the preamble of claim 7, which base is arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water.

Furthermore, the invention relates to an arrangement for water sports according to independent claim 18.

The preferred embodiments of the invention have been disclosed in the dependent claims.

The object of the footwear and base according to the invention to make it possible for the athlete to move in the water by using the bottom of the pool for pushing for more speed with his feet, preferably in a steep forward lean, in such a way that the movement of the athlete is not essentially slowed down by the slipperiness of the pool bottom or the buoyancy of the water. In this case the movement more closely resembles running in a forward-leaning position than walking up straight. The athlete can be under water either entirely or in part, and the depth of the water may vary. If necessary, the athlete may be further equipped with for instance a snorkel.

As the athlete moves in the water, his position resembles the strong forward lean of a ski jumper, the purpose of which is to be as streamlined as possible. In ski jumping, the strong forward lean is made possible by the bed of air underneath the body of the jumper, against which the jumper leans. In dive running, the resistance of the water forms a similar kind of bed against which the runner leans. However, the resistance of water is so much greater than air's that considerably less speed is required in water in order for it to function as a sufficient resistance for leaning forward. Thus, the resistance of water "carries" the upper body of the runner while he is leaning forward during his exercise.

The formation of the sole of the footwear according the invention is adapted to function together with the base arranged in water. The formation of the sole of the footwear comprises one or more projections, which one or more projections may comprise a ridge or a stud or a combination thereof. The one or more projections arranged in the sole of the footway may be detachable or attached to the bottom in a permanent manner. The projection arranged in the sole of the footwear may be arranged at the toe of the footwear or near the toe in the sole of the footwear, or into the sole under the ball of the foot, or elsewhere in the sole of the footwear, and there may be one or several projections, even so that the entire sole of the footwear is covered with projections. In one solution according to the invention, one or more ridges have been provided in the footwear, preferably running in a lateral or longitudinal direction across the sole of the footwear, or the said one or more ridges may be arranged diagonally across the sole of the footwear. The ridge may be arranged in the sole of the footwear for instance at an angle with respect to the lateral direction. Preferably, the said one or more ridges protrude outwards from the sole of the footwear. Holes, grooves and recesses are formed between the projections that protrude outwards from the sole, or the edges of the holes, grooves and recesses form outward-protruding ridges. The ridge may be located at the toe of the footwear, in which case there is preferably one ridge, or in the footwear under the ball of the foot, in which case there can preferably be one or more ridges. Ridges may also have been arranged in the sole of the footwear also elsewhere than the toe of the footwear or under the ball of the foot, and the sole of the footwear may for example be entirely covered with ridges. The said ridge may comprise of one or several different parts, such as two or more adjacent studs or partial ridges, preferably forming one cross-directional ridge assembly in the lateral direction of the sole of the footwear. The ridge is preferably detachable and can for instance be replaced with a new one, or in case there is more than one ridge, the places of the ridges can the changed. Several attachment points have been arranged in the sole of the footwear for attaching one or more ridges, but a ridge does not have to be attached to every point. For instance, ridges that have a different size or profile may be attached to the sole of the footwear. The ridges may be located next to each other or in an interlaced manner, and they can be in a symmetrical or unsymmetrical order. The angle of the ridge with respect to the sole of the footwear may be altered by using the attachment points in the sole. The sole of the footwear and its ridges can also be manufactured in a fixed manner, so that the number, location or angle or the ridges cannot be changed.

In another solution according to the invention, one or more studs have been arranged in the footwear used in water sports, each stud extending outwards from the sole of the footwear. Preferably, the stud can be released and for instance replaced with a new one or, in case there is more than one stud, the places of the studs can be changed. Several attachment points have been arranged in the sole of the footwear for attaching one or more studs, but a stud does not have to be attached to every point. For instance, studs that have a different size or profile may be attached to the sole of the footwear. The studs may be located next to each other or in an interlaced manner, and they can be in a symmetrical or unsymmetrical order. The sole of the footwear and its studs can also be manufactured in a fixed manner, so that the number, location or angle or the studs cannot be changed.

In another solution according to the invention, one or more ridges and one or more studs have been arranged in the footwear used in water sports in the above-described manner.

Preferably, the sole of the footwear is made of natural rubber, synthetic rubber, a combination of natural and synthetic rubbers or of any other suitable material, and it is preferably flexible.

The base for water sports arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, is adapted to function together with the formation of the sole of the footwear used in water sports. The surface of the base comprises a structure adapted to function together with the formation of the sole of the footwear, which formation of the sole of the footwear comprises one or more projections. Therefore, the structure can be located only on the surface of the base. In another embodiment, the structure of the base comprises a structure adapted to function together with the formation of the sole of the footwear, which formation of the sole of the footwear comprises one or more projections. Therefore, the structure can extend through the entire base instead of being restricted to the mere surface part thereof, like for instance a sheet comprising thorough holes. The structure of the base can consist of grooves, ridges, holes, recesses or other forms that either perforate or do not perforate the base. The forms that do not perforate the base are typically located under the surface of the base, such as circular recesses, which however are not thorough holes. The forms that do not perforate the base can, of course, continue in part over the surface, like for instance a combination of a recess and a ridge. The base can be made of metal, natural rubber, synthetic rubber, a combination of natural and synthetic rubbers or of any other material that is suitable for the inventive purpose and, if necessary, it can be flexible. The base can be temporarily and/or detachably arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, for water sports. The base can be arranged on the bottom of a swimming pool or a corresponding space used for water sports and filled with water or on the bottom of natural water in such a way that there is also water under the base.

In one solution according to the invention, the base used in water sports is preferably detachably arranged in a swimming pool or other corresponding space suitable for water sports. Preferably, the base is arranged on the bottom of the pool or the space, but it may also be for instance be installed in a floating manner, entirely or in part, or installed on supporting structures.

The base according to the invention is preferably equipped with grooves or holes in such a way that the projection located in the sole or the athlete's footwear, for instance a ridge or a stud, can temporarily attach to the said groove or hole, so that the athlete obtains a good grip of the bottom through his footwear and is able to lean forward, even steeply, while pushing. The grooves or holes may perforate the entire base or only extend partly through the thickness of the base.

One embodiment according to the invention comprises ridges between which grooves are formed. The said ridges provided in the base extend essentially upwards from the base. The ridges run in a cross direction in the base, either in a uniform manner from one side to another, or they may consist of several shorter partial ridges, such as studs, located side by side. Between the ridges in the base, grooves are formed in a longitudinal direction, into which the ridges or studs provided in the bottom of the footwear fit. The form of the ridge provided in the base may either widen or narrow from bottom to top. The form of the ridge may also be uniform, an hourglass or any other suitable form, or the ridge may for example be formed to resemble a wave. When the ridge widens from bottom to top, it functions in a hook-like manner, in which case its form is especially preferable for diminishing the effect of buoyancy of the water on the athlete and for preventing the sole of the footwear from disengaging from the base because of the buoyancy of the water as the athlete is leaning forward. The distance between the ridges may vary.

According to another embodiment of the invention, the base contains holes that may be thorough holes or extend only through part of the thickness of the base. The holes of the base are preferably round, circular ones, but they may also have some other shape, for instance be oval or angular. The holes of the base can be in a symmetrical or unsymmetrical order, according to need. The distance of the holes from each other can vary, and they may be of the same or different size, as needed. The width of the holes of the base can narrow, widen or stay the same from bottom to top. The hole can also be wider or narrower as measured in the middle than in its bottom and top parts.

In the base according to the invention, the above-mentioned forms may also be mixed. Also other combinations are possible. Preferably, the profile of the base is such that one is able to move along it backward and forward in the same way. Also moving sideways or in an oblique direction with respect to the mat is possible depending on the arrangement, form and size of the holes and/or ridges provided in the base and/or the sole of the footwear.

The base according to the invention can be made of metal, preferably stainless steel, plastic, rubber or any other corresponding material suitable for the present use, or it may comprise a combination of two or more materials. The ridges can be obtained preferably by bending, casting, milling, cutting, injection moulding, welding or mechanically joining different parts. The height, width and thickness of the ridge as well as the distance between the ridges can vary according to need.

The base can preferably be assembled from parts, whereby the parts of the base are joined together for instance by a mechanical joint, in which case it is easy to assemble and disassemble, if necessary. The base can also be a uniform base, for instance a base that can be rolled out, in which case it is preferable that the material of the base is such that it is suitable for rolling up, such as for instance plastic or rubber. A hinged or netlike base made of metal can also be arranged for instance on the bottom of a swimming pool by rolling it out. The base can also be an integral part of the pool, such as for instance a surface formed on the pool bottom by tiling or metal lathing.

As much of the base can be arranged on the bottom of the pool or a similar space as is necessary, even covering the entire surface area of the pool bottom, or only a part of it. The base can also be arranged in a pool or a corresponding space in such a way that a layer of water remains under the base. This can be achieved for instance by various support structures. The base can be arranged in the pool in any direction, for instance in a longitudinal and/or lateral direction of the pool. The base can also be manufactured according to the measurements of the pool, if it has a less common shape, for instance if the pool is round. The base can also be arranged in natural water.

The place in held in place on the bottom of the pool or any other similar space used for water sports by its own weight, by movable and detachable separate weights or by any other mechanical means of attachment. For instance, silicone pads can be provided in the bottom of the base in order to keep the base better in place and to prevent it from sliding along the bottom.

In a preferred embodiment, a base equipped with special grooves or holes is rolled out on the bottom of the pool. In the sole of the athlete's footwear, there is pattern that connects with the base or fits into it, such as a stud or a ridge. As the pattern in the sole of the athlete's footwear hits the grooves or holes in the base, the athlete is able to push for more speed from the bottom of the pool, and at the same time the effect of the slipperiness and buoyancy on the athlete and especially his pushing foot is preferably prevented, thus preventing the foot from coming off the base. The grooves or holes of the base function like the starting block of a runner, providing good support for the pushing foot and preventing the athlete's foot from slipping backwards.

In one embodiment according to the invention, one or more walls can be detachably and movably mounted on the base, which the athlete can use for performing turns or kicking for more speed.

The invention also comprises an arrangement for water sports, the arrangement comprising footwear used in water sports and a base arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water. In the arrangement, the footwear comprises a sole the form of which is a adapted to function together with the formation of the base, and one or more projections have been provided in the sole of the footwear, which are adapted to function together with the structure of the base. The one or more projections and the structure of the base are adapted to function together in such a manner that the one or more projections provided in the sole of the footwear fit into the structure of the base.

The invention also comprises footwear used in water sports, the footwear comprising a sole, and a base for water sports arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, wherein the one or more projections provided in the sole of the footwear and the structure of the base are adapted to function together in such a manner that the one or more projections provided in the sole of the footwear can be fitted in a detachable manner into the one or more grooves, holes, recesses or any other forms that form the structure of the base and that either perforate or do not perforate the base.

The advantage gained by one preferred embodiment of the footwear and base for water sports according to the invention is that these enable the athlete to increase his forward lean without slowing down the movement due to the slipperiness of the pool and the buoyancy of the water. With the help of the base and the footwear, the athlete can proceed in a dive-like manner almost in a horizontal position by kicking for more speed from the base arranged on the bottom. The footwear and the base make it possible to obtain a similar thrusting force as when using fins, with the exception that a base arranged on the bottom of the pool is used for kicking for more speed. The footwear and the base can be used by anyone doing water sports, whether this person is a top athlete or an amateur performing fitness training. The base can be arranged in a pool which is so deep that the athlete mainly moves under the water surface using for instance a snorkel or an oxygen tank, or in a pool that is shallow, so that the athlete moves with his head above the water. The base can also be arranged in a pool in which the depth of the water varies. The base can also be arranged in natural water.

An athlete using the footwear according to the invention that comprises the sole according to the invention can engage in various kinds of water sports by using the base. One example is water running underwater, in the starting position of which the athlete is positioned his face underwater and back upwards towards the running direction. The athlete holds himself in place for instance by gripping a handle behind his back, with his feet against the wall of the pool. After receiving the starting signal, the athlete releases his grip on the handle and pushes forward with his feet. Immediately after pushing, the athlete extends his hands forward and, at the latest when reaching a specific mark, starts to run by kicking the pool bottom for more speed. When he reaches the mark, the athlete also starts to scoop with his hands so that the movement resembles running. What is important for the athlete is to find a position and movement that are as streamlined as possible. His face must stay under water the entire time. The turn at the end of the pool takes place in the same way as in swimming, by kicking against the end wall of the pool to gain more speed. After the turn, there will be a new mark before which the athlete must start treading the pool bottom and scooping with his hands.

According to the invention, there has been provided footwear used in water sports, the footwear comprising a sole, the sole comprising a formation, and which footwear is used in sports that take place in water, the formation of the sole of the footwear comprising one or more projections, the one or more projections being adjusted to function together with the structure of the base arranged in water in such a way that the one or more projections are supported on the structure of the base and the footwear is prevented from slipping backwards.

According to the invention, there has been provided a base arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, wherein the surface or construction of the base comprises a structure adapted to function together with the formation of the sole of the footwear used in water sports, the formation of the sole of the footwear comprising one or more projections.

According to the invention, there has been provided an arrangement for water sports, the arrangement comprising footwear used in water sports, the footwear comprising a sole, and a base for water sports arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, wherein one or more projections have been provided in the sole of the footwear and the base has a structure and wherein the one or more projections provided in the sole of the footwear are adapted to function together with the structure of the base. In the arrangement, the one or more projections provided in the sole of the footwear and the structure of the base are adapted to function together in such a way that the one or more projections provided in the sole of the footwear fit into the structure of the base. The one or more projections provided in the sole of the footwear and the structure of the base are adapted to function together in such a way that the one or more projections provided in the sole of the footwear can be detachably fitted manner into one or more grooves, holes, recesses or any other forms that either perforate or do not perforate the base.

In an arrangement according to one embodiment, the said one or more projections provided in the sole of the footwear comprise a ridge.

In an arrangement according to one embodiment, the said one or more projections provided in the sole of the footwear comprise a stud.

In an arrangement according to one embodiment, the projection provided in the sole of the footwear is releasable.

In an arrangement according to one embodiment, the projection provided in the sole of the footwear has been provided at the toe of the footwear.

In an arrangement according to one embodiment, the projection provided in the sole of the footwear has been provided in the footwear under the ball of the foot.

In an arrangement according to one embodiment, the structure of the base consists of grooves.

In an arrangement according to one embodiment, the structure of the base consists of ridges.

In an arrangement according to one embodiment, the structure of the base consists of holes.

In an arrangement according to one embodiment, the structure of the base consists of recesses or other forms which are located on the surface of the base but do not perforate the base.

In an arrangement according to one embodiment, the base is made of natural rubber, synthetic rubber, or a combination of natural and synthetic rubbers.

In an arrangement according to one embodiment, the base is made of metal. In an arrangement according to one embodiment, the base is flexible.

In an arrangement according to one embodiment, the base is temporarily arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, for water sports.

In an arrangement according to one embodiment, the base is detachably arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water.

In an arrangement according to one embodiment, the base is arranged in a swimming pool or a corresponding space used for water sports and filled with water, or in natural water, in such a way that there is also water under the base.

List of Figures

In the following, some preferred embodiments of the invention are presented in more detail by referring to the attached figures in which

Fig. 1 shows a preferred embodiment of the sole the footwear according to the invention and used in water sports,

Fig. 2 shows a side view of the sole of the footwear presented in Fig. 1,

Fig. 3 shows the sole of the footwear presented in Fig. 1 as viewed from an upward angle,

Fig. 4 shows another preferred embodiment of the footwear according to the invention and used in water sports,

Fig. 5 shows a side view of the sole of the footwear presented in Fig. 4, Fig. 6 shows the sole of the footwear presented in Fig. 4 as viewed from a upward angle,

Fig. 7 shows a preferred embodiment of the sole the footwear according to the invention and used in water sports,

Fig. 8 shows the base presented in Fig. 7 as viewed from a downward angle,

Fig. 9 shows another embodiment of the base according to the invention and used in water sports,

Fig. 10 shows a third embodiment of the base according to the invention and used in water sports,

Fig. 11 shows a side view of the base presented in Fig. 10,

Fig. 12 shows a fourth embodiment of the base according to the invention and used in water sports,

Fig. 13 show a further embodiment of the base according to the invention and used in water sports, Fig. 14 shows a side view of the sole of the footwear presented in Fig. 1 and the base presented in Fig. 12,

Fig. 15 shows the sole of the footwear and the base presented in Fig. 14 as viewed from a downward angle, and

Fig. 16 shows a side view of the sole of the footwear presented in Fig. 1 and the base presented in Fig. 11.

Detailed Description of the Invention

Fig. 1 shows one embodiment of the footwear according to the invention and used in water sports, in which Figure only the sole 1 of the footwear has been depicted. In this embodiment, three ridges 2 extend outwards from the sole 1 of the footwear, these being located in the front part of the sole 1 of the footwear essentially under the ball of the foot. There may also be some other number of ridges 2 besides three, for instance even one is enough, and on the other hand the entire sole 1 of the footwear may be covered with ridges 2.

Fig. 2 shows a side view of the sole 1 of the footwear according to Fig. 1.

In this embodiment, the profile of the ridge is uniform and rounded at the end, but it may also have some other shape. As was stated above, the amount of ridges 2 can vary from one to several according to need. If there is only one ridge 2, this one ridge is preferably located in the front part of the sole 1 of the footwear, preferably at or near the toe. Of course, the ridge 2 can also be located elsewhere in the sole 1 of the footwear.

Fig. 3 shows a further view of the sole of the footwear according to Fig. 1 as seen from an upward angle. This figure shows that the ridges 2 preferably cover the entire sole 1 of the footwear in the lateral direction and have been formed in a uniform manner. The ridge 2 may also comprise of several successive parts, or the ridge may only cover part of the sole 1 of the footwear in the lateral direction. The ridge 2 may for instance be located only in the middle part of the sole 1 of the footwear, in which case the edge zones of the sole 1 of the footwear remain ridge-free.

Fig. 4 shows a further embodiment of the footwear for water sports according to the invention, in which figure only the sole 1 of the footwear has been depicted. In this embodiment, one stud 3 extends outwards from the sole 1 of the footwear, this being located in the sole 1 approximately under the ball of the foot, in the middle. In this embodiment, the stud 3 is rounded at its ends, but it can also have some other shape, for example be mushroom-like with a straight stem, the head of the stud 3 forming a cap on the top of the stem. Fig. 5 shows a side view of the sole 1 of the footwear according to Fig. 4. As can be seen from the figure, the stud 3 can have a uniform thickness and it can be rounded at the ends. The stud 3 can also have some other shape, for instance be somewhat mushroom-like, with the head of the stud being wider than the stem. Also other forms are possible.

Fig. 6 shows a further view of the sole of the footwear according to Fig. 4 as seen from an upward angle. As was stated above, the sole of the footwear can comprise one or more studs 3. Even when there is only one stud 3 in the sole 1, this may be located elsewhere instead of under the ball of the foot, like for instance at the toe of the sole 1 of the footwear.

Fig. 7 shows a preferred embodiment of the base 4 used for water sports according to the invention, which base 4 can be installed on the bottom of a swimming pool or some other space suitable for water sports. In this embodiment, the base 4 is preferably formed by bending a metal sheet in order to obtain a profile where bottom parts 5 alternate with ridges 6. In this embodiment, the ridge 6 can preferably widen upwards, forming a slightly hooklike structure together with the bottom part 5. The ridge 6 may also have some other shape, for instance be uniform or wavy.

Fig. 8 shows two bases 4 according to Fig. 7 attached to each other. In this example, the bases 4 have been attached, with respect to the ridges 6, to each other from their sides A, B in such a way that side A of one base 4 is attached to side B of another base 4. The attachment can achieved through separate mechanical means of attachment, such as different clamps, or some kind of mounting slot can be provided at the edge of side A, B, which slot, as it meets side B of the other base 4, joins the bases 4 together. In that case, the sides A, B, which run transversely with respect to the ridges 6 of the base 4, need to be slightly different from each other in order for them to be able to function together as they meet. The bases 4 can also be attached to each other from sides C, B, running in the same direction as the ridge 6. Also this attachment can be made by mechanical means of attachment, or by mounting slots provided in the base 4, or by some other means.

Fig. 9 shows a further embodiment of the base 4 according to the invention, which base 4 is used for water sports and can be installed on the bottom of a swimming pool or in some other space suitable for water sports. In this embodiment, the base 4 is preferably formed by bending a metal sheet in order to form a profile in which bottom parts 5 alternate with ridges 6. The profile of the ridges 6 is different from the profile shown in Fig. 7, since in this embodiment the profile of the ridge 6 is slightly tapered upwards. Fig. 10 shows a further embodiment of the base 4 according to the invention, which base 4 is used for water sports and can be installed on the bottom of a swimming pool or in some other space suitable for water sports. In this embodiment, the base 4 is preferably formed of injection moulded plastic or some other suitable material, so that it has a profile in which bottom parts 5 alternate with ridges 6. In this figure, two bases 4 are located next to each other, and these have preferably been attached to each other. The attachment can be permanent, or it may be arranged in a detachable manner. The attachment that joins the two bases 4 together can take place from the sides A, B running transversely with respect to the ridges, or the two bases 4 can be joined together from the sides C, D, which run parallel with the ridges. The attachment of the base 4 on the bottom of a pool or a corresponding space can be accomplished for instance by using suction cups or weights.

Fig. 11 shows a side view of the base according to Fig. 10. In this embodiment, the profile of the ridge 6 is slightly tapered upwards.

Fig. 12 shows a further embodiment of the base 4 according to the invention, which base 4 is used for water sports and can be installed on the bottom of a swimming pool or in some other space suitable for water sports. The base 4 had preferably been formed by injection moulding suitable material, such as plastic or a vinyl plastic compound. In this embodiment, the profile of the ridge 6 forms a slightly hook-like structure in the upper part of the ridge 6.

Fig. 13 shows a still further embodiment of the base 4 according to the invention, the base 4 being provided with holes 7. Preferably, the holes are preferably circular, but they may also have some other shape, for instance be oval or angular. The arrangement of the holes 7 in the base can be symmetrical or unsymmetrical. In this Figure, the holes 7 are thorough holes, but they may in some other embodiment only extend through part of the thickness of the base 4. The figure shows four square-shaped bases 4 attached to each other. Preferably, the bases 4 have been attached to each other in a detachable manner. The base 4 may also have some other shape than square. For instance, the base 4 can be a long mat rolled out on the bottom of the pool.

Fig. 14 shows a side view of both the embodiment of the sole 1 of the footwear used in water sports according to Fig. 1 and the embodiment of the base 4 used in water sports according to Fig. 12 as seen together. The ridges 2 in the sole 1 of the footwear fit into the grooves provided in the base 4, and as the athlete wishes to move forward, he can kick for more speed by using the ridge 6 provided in the base 4, the profile of the ridge preferably being adjusted to diminish the effect of the buoyancy of the water on the athlete, thus making it easier for him to move forward underwater. In this embodiment of the base 6, the profile of the ridge is preferably hook-like, in which case the ridge 2 of the sole 1 of the footwear functions together with the hook-like profile of the ridge 6 of the base, thus diminishing the effect of the buoyancy of the water on the athlete.

Fig. 15 shows the sole 1 of the footwear and the base 4 according to Fig. 14. as viewed from an downward angle. The Figure shows how the shape of the profile of the ridge 6 functions together with the ridge of the sole 1 of the footwear, diminishing the effect of the buoyancy of the water on the athlete.

Fig. 16 shows a side view of both the embodiment of the sole 1 of the footwear used in water sports according to Fig. 1 and the embodiment of the base 4 used in water sports according to Fig. 11. In this embodiment, the profile of the ridge 6 of the base 4 is different than in the embodiment shown in Fig. 14; i.e., it is tapered upwards. The ridge 2 of the sole 1 of the footwear also functions together with such a profile of the ridge 6 of the base 4, providing the athlete with a contact surface that he may use to push forward.

It is obvious for a person skilled in the art that as the technique advances, the basic principle of the invention may be implemented in several different ways. The invention and its embodiments are therefore not restricted to the above- described examples but may be varied within the scope of the claims.