Patent Publication Number: US-10765916-B2

Title: Swim Shoe

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention concerns a swimming shoe for learning and/or for support of the leg kick for breaststroke swimming and a swimming shoe production process. 
     Related Technology 
     Such swimming shoes are for example known from the documents DE 26 58 584 A1 and DE 10 2007 003 508 B3. They are used as swimming and learning aids, to make it easier to learn to swim, on the one hand, and also to practice as well to continually check for the correct breaststroke swimming technique, on the other hand. 
     These known swimming shoes have a sole flap, which can be swiveled to the outer side of the foot by means of a kind of hinge design. In the case of this shoe, the flap goes up when the stroke is executed, so that it becomes immediately noticeable whether the foot position is correct or not by way of the thereby increased kicking area of the feet. If the legs, more accurately said the lower legs, are drawn toward to the buttocks during the continued swimming movement, the flap swiveling with almost no resistance then closes because of the drag. In the subsequent rotary swinging movement until the legs stretch out, the flap opens up again, so that better propulsion comes about due to the increased repelling area of the feet. The person wearing the swimming shoe thus feels very soon while performing the breaststroke kick whether his foot position is correct or wrong. If the wearer of the swimming shoe gets different feedback signals from his left and his right swimming shoe, he can conclude very quickly that his left and his right legs do not move symmetrically, and he can immediately correct this. 
     Such swimming shoes have a good record in practice. With further development in accordance with DE 10 2007 003508 B3, a further improvement was achieved, in that an adjustment of the maximum swiveling angle of the sole flap was made possible so as to adjust the supporting effect of the swimming shoe in this way, and to allow for safe walking with the swimming shoe outside of the water. The hinge-like joint configuration provided by two textile straps in this known case, with one textile strap located at the inside of the hinge at the sole of the shoe body and the top of the sole flap and the other textile strap positioned at the outside of the hinge at a flap nose and at the side surface of the shoe body. The textile straps are, e.g., attached to the respective sections with a high-strength adhesive. 
     Aside from the fact that the known structure of the hinge joint design is relatively complex and that it is therefore more difficult to produce, it is found that, with prolonged use, the sole flap is not always reliably pressed against the soles because of the pre-tensioning of the joint. This known swimming shoe therefore has manually actuated fixer equipment, by means of which the sole flap is held parallel to the floor surface when walking outside the pool. This makes the construction of the swimming shoes slightly more elaborate. 
     SUMMARY 
     It is therefore the object of this invention to further develop a generic swimming shoe, such that it assures long term functionality with great ease of use by way of a simplified design. 
     According to the invention, an elastic strap is used, through which the sole flap is connected with the shoe body, whereby the strap presses the sole flap flexibly with pre-tensioning against the floor space of the shoe body. When the sole flap swivels away from the shoe body, the elastic strap stores energy in the form of a pre-tensioning force, which is used to swing the sole flap back onto the shoe body. With the strap pressing the sole flap against the floor space of the shoe body, this has the benefit that walking with the swimming shoe outside of the water is facilitated. This is because the flexible strap prevents the sole flap from unintentionally moving and/or swinging away. Without water resistance, the sole flap always rests against the floor space of the shoe body with sufficient pre-tensioning of the strap. The size of the strap can be varied over a wide range. This enables a robust construction of the swimming shoe of this invention, its long-term functionality being assured. 
     According to this invention, it is furthermore not necessary to provide any additional immobilization of the sole flap for walking outside of the water. This is because the sole flap always automatically rests against the floor space of the shoe body because of the pre-tensioning of the strap. According to this invention, the sole flap basically no longer requires a stop. For, because of the pre-tension, a sufficient feed force can be generated by way of the leg kick before a limiting swivel angle is reached. 
     This has the additional advantage that it remains economical to produce the swimming shoe. For the elastic strap can be produced either simply as an integral part of the shoe body or separately by an injection molding process. 
     In one embodiment, the entire length of the strap can be used to provide the joint function. The swiveling section swivels along with the sole flap because of the water resistance, and then presses the sole flap to the floor space of the shoe body with pre-tensioning. Such a simple construction enables the swiveling of the sole flap, while the size of the strap can influence the pre-tensioning force. 
     In another embodiment, the swivel angle is limited by the impact of the sole flap or the strap on the shoe body, but not by the elastic limit of the strap. This has the advantage that the strap does not reach its elastic limit and the service life of the strap is thus extended. 
     It is through the strap constituting an integral part of the shoe body that, the strap may be produced as part of the shoe body. This reduces the production effort as well as the cost. 
     In an embodiment, the strap is attached separately to the shoe body. This has the advantage that the strap and the shoe body can be made of different materials. The strap can, e.g., be made of a reinforced and possibly more expensive material so as to provide reliable functioning, while the shoe body can be made of an unreinforced and thus usually more economical material optimized for wearing comfort. This enables economical production. 
     The swivel section can be subdivided into several fastening tongues with different assigned functions. A further increase in the flexibility of the design is thus achieved. 
     The strap can may be successfully firmly connected with the sole flap since the fastening tongue is positioned in a sandwich-like manner between the bridge and the outer section the sole flap. The assembly is furthermore simplified, since the bridge controls the position of the strap and its attachment point. This additionally provides for a better appearance. 
     In an embodiment, the construction of the sole flap is simplified. It is through the interlacing of the fastening tongues of the strap into the sole flap that the link is stabilized. 
     In a further embodiment, the pre-tensioning tongue provides additional supporting force, which acts on the sole flap, so that it is possible to do without fastening the pre-tensioning tongue to the sole flap. 
     The sole flap may be installed and exchanged with the strap. 
     An embodiment, according to which numerous ribs are installed at the bottom of the sole flap, has the advantage that the sole flap is prevented from changing its shape when it is deflected or swings out. The ribs can, in addition, be given an anti-sliding function. 
     In an embodiment, the ribs preferably extend in the cross direction of the shoe body. With this direction of extension of the ribs the sole flap gets the rigidity required for supporting the leg kick, while it does not obstruct a rolling movement of the swimming shoe while running. User safety is therefore improved. 
     The weight of the sole flap can be reduced via the further development in an embodiment wherein the sole flap furthermore has two recesses at the outer section. 
     The strap does not necessarily have to have the same wall thickness everywhere. For example, a rib extending along the swiveling axis can be formed at the location between the swiveling and the non-swiveling section. This location can thus become heavier if the strap is in a bent condition. This location is therefore strengthened by the rib. Long-term functionality is therefore improved. 
     Experiments have shown that just one strap of a material may suffice to create sufficient pre-tensioning, with a strap thickness of 3 mm to 5 mm being sufficient. This offers the possibility of making the strap and the shoe bodies of one and the same material, preferably by injection molding. 
     If the shoe body is configured symmetrically so that it is symmetrical with respect to a longitudinal center axis, the swimming shoe can be produced economically, for example by injection molding. This is because only a single injection mold is needed for a pair of swimming shoes, for both the right shoe body and the left shoe body. 
     The production process in accordance with claim  18  enables may enable economic production. This is because the strap is, on the one hand, produced via the injection molding process as an integral part of the shoe body, and only one injection mold is needed for both shoe bodies, the right and the left shoe body, of a pair of swimming shoes. This results in economical production. If, on the other hand, the strap and the shoe body are produced separately by an injection molding process, they can be made of different materials. This production process as well requires only one shoe body, only one strap and —for the second embodiment with the interlaced fastening tongues —only one sole flap is required, which can be used for both shoes, the left shoe as well as the right shoe. This leads to an additional simplification of the production process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the invention are hereinafter described in greater detail by means of schematic drawings, which show: 
         FIG. 1  a perspective view of a swimming shoe according to this invention for the right foot in accordance with a first embodiment; 
         FIG. 2  a view from below of the swimming shoe in accordance with the first embodiment; 
         FIG. 3  the cross-section A-A in  FIG. 2 , wherein the nib is omitted; 
         FIG. 4  a perspective view of a swimming shoe according to this invention in a mounted condition in accordance with the first embodiment, in which the sole flap is omitted; 
         FIG. 5  a perspective view of a shoe body and a strap in the raw form in accordance with the first embodiment after it is taken out of an injection mold; 
         FIG. 6  a perspective view from a top side of a sole flap for a swimming shoe in accordance with the first embodiment; 
         FIG. 7  a perspective view from the bottom of a sole flap of the swimming shoe in accordance with the first embodiment; 
         FIG. 8  a perspective view of a swimming shoe for the right foot in accordance with a second embodiment; 
         FIG. 9  a view from the bottom of the swimming shoe in accordance with the second embodiment; 
         FIG. 10  the cross-section B-B in  FIG. 9 ; 
         FIG. 11  a perspective view of a swimming shoe according to this invention in a mounted condition in accordance with the second embodiment, in which the sole flap is omitted; 
         FIG. 12  a perspective view from a top side of a sole flap for the swimming shoe in accordance with the second embodiment; 
         FIG. 13  a perspective view of an alternative of the second embodiment of the sole flap similar to  FIG. 12  at a somewhat magnified scale; and 
         FIG. 14  the perspective view of the sole flap in accordance with  FIG. 13  as seen from below. 
     
    
    
     DETAILED DESCRIPTION 
     A swimming shoe, particularly the right swimming shoe, for learning and/or for support of the leg kick for breaststroke swimming is assigned the reference number  10  in the figures. No description of the left swimming shoe is provided here, since it is a mirror image of the right swimming shoe. 
     The swimming shoe is described in accordance with a first embodiment is hereinafter described with reference to  FIGS. 1 to 7 . 
     As shown in  FIG. 1 , the swimming shoe  10  mainly consists of two parts, i.e. the actual shoe body  12  and a sole flap  14  shown separately in  FIGS. 6 and 7 , which is attached thereto via a hinge coupling  18 , which is to be described in greater detail. The hinge coupling  18  has an elastic strap  20  by means of which the sole flap  14  is connected with the shoe body  12 , such that, through its elastic bending deformation, the strap  20  flexibly presses the sole flap  14  with pre-tension against a floor space  32  of the shoe body  12 . When the swimming shoe is used as a swimming aid and/or as an aid in learning to swim, the flexible strap  20  builds up a pre-tension via additional elastic bending deformation when the sole flap  14  is swung away from the shoe body  12 , and this pre-tension is used to swing the sole flap  14  back onto the shoe body. 
     In this embodiment, the strap  20  is produced as an integral part of the shoe body  12  by injection molding, i.e. it is molded onto the shoe body. The shoe body  12  with the strap  20  is made of a thermoplastic elastomer, preferably a thermoplastic elastomer based on urethane (TPU). The sole flap  14  is configured as a synthetic injection molded part. 
       FIG. 5  shows the flexible strap  20  in a relaxed state, for example in the form in which it comes out of the injection mold together with the shoe body. The sole flap is not mounted yet. The strap is as yet unprocessed. In this relaxed state, a part of the flexible strap  20  projects over the floor space  32  of the shoe body  12 . 
     As shown in  FIGS. 3 and 4 , the section of the strap  20  protruding above the floor space is bent outward in the mounted state of the sole flap and is connected with the sole flap  14 . It is because of this elastic bending deformation of the strap  20  that a pre-tension builds up, through which the sole flap  14  is flexibly pressed against the floor space  32  of the shoe body  12 . This projecting section of the strap  20  forms a swivel section  30 , which can swivel along with the sole flap  14  due to water resistance when kicking. The section protruding over the floor space  32  forms a not swiveling or non-swiveling section  28 , which is connected with the shoe body  12 . A swivel axis  16  of the hinge coupling  18  lies between the swiveling section  30  and the non-swiveling section  28 . The entire length of the strap can thus be used for providing the hinge function. 
     The strap  20  in the form of a piece of cloth has a uniform wall thickness and—depending on the material—a thickness din the range of 3 mm to 5 mm. It can be shown in experiments that long-term functionality can be ensured. 
     The strap does not necessarily have to be made with same wall thickness everywhere. A reinforcing ridge  60 , which extends along the swivel axis  16  (this alternative is shown with cross-hatches in  FIG. 5 ), can, for example, be placed between the swiveling section  30  and the non-swiveling section  28 ). 
       FIG. 2  shows a view of the swimming shoe  10  in accordance with the first embodiment as seen from below. The sole flap  14  has an outer section  22  to which the swiveling section  30  of the strap  20  is fastened and an inner section  24 , which rests against the floor space  32  of the shoe body  12  when it is at rest. The sections  22  and  24  are separated from each other by the swivel axis  16 . 
     The nature of the connection between the strap  20  and the sole flap  14  in accordance with the first embodiment is hereinafter described in greater detail. 
     As shown best by  FIGS. 6 and 7 , the sole flap  14  has a bridge  26 , which projects upward from the sole flap  14  and contains a first end section  34 , a second end section  36  and a base plate  38 , whereby a slot  40  is formed between the bridge  26  and the outer section  22 , into which the swivelable section  30  of the strap  20  can be introduced as a fastening tongue  42 , as shown in  FIGS. 3 and 4 . 
     To fasten the sole flap  14 , the fastening tongue  42  is inserted into the slot  40  from inside. The outer contour of the fastening tongue  42  thus follows the contour of the slot  40 . The fastening tongue  42  and thus the strap  20  can be detachably connected to the sole flap  14 . In the embodiment shown, there are three drilled cutouts and/or drill holes  58  in the base plate  38  of the bridge  26  of the sole flap  14 , three drilled cutouts and/or drill holes  61  in the outer section  22  of the sole flap  14  and three drilled cutouts and/or drill holes  59  in an end section  43  of the fastening tongue  42  of the strap  20 , which are mutually aligned and can be respectively introduced into a nib and/or a stud. The cutouts  58 ,  59 ,  61  are aligned with each other regarding their position, such that as shown in  FIG. 3  the sole flap  14  lies flat on the floor space  32 . The three connecting points are essentially located along the longitudinal direction of the swimming shoe  10 . The strap  20  is thus positioned by the bridge  26  and is attached to the sole flap  14  in a sandwich-like manner. 
       FIG. 3  shows the state of the swimming shoe  10  with the mounted sole flap  14 . One can see that the sole flap  14  is pressed against the floor space  32  of the shoe body  12  by pre-tension, with the swiveling section  30  of the strap  20  bent outward at about 90°. The sole flap  14  can also jut out slightly beyond the floor space on the side opposite the hinge configuration. If the leg kick is performed correctly, the sole flap goes up because of the water resistance. As long as the water pressure is higher than the pre-tensioned force of the strap  20 , the water is pushed into the space between the sole flap  14  and the floor space  32  of the swimming shoe  10 , whereby the sole flap  14  is pushed to about 90° by the water resistance and a topside  27  of the bridge  26  strikes the sidewall of the shoe body  12 . When the legs, more accurately the shanks, are pulled toward the buttocks, the sole flap  14 , which essentially experiences no resistance, closes because of the drag and the pre-stressed state of the strap  20 , while the water is displaced from the space between the sole flap  14  and the floor space  32  of the swimming shoe  12 . The sole flap  14  is again opened up during the subsequent rotary swinging movement until the legs stretch out. The swimmer thus feels very soon whether his foot position is correct or wrong. 
     The sole flap  14  according to this embodiment furthermore has numerous ribs  44 . These ribs  44  are located at the bottom  47  of the sole flap  14  and extend across the longitudinal axis of the shoe body  12 . Selected ribs  62  of the ribs  44  extend through the three junction points. When the swimmer wears the swimming shoes and walks outside of the water, the sole flap with pre-tensioning of the strap rests against the floor space of the shoe body. The pre-tensioning of the strap and the ribs extending in the transverse direction prevent the sole flap from unintentionally moving and/or swinging out, while a rolling motion of the swimming shoe is not obstructed because the ribs extend in the transverse direction. 
     As shown in  FIG. 2 , the outer section  22  of the sole flap  14  furthermore has two recesses  46 , which are located under the bridge  26  between the three ribs  62  extending through the three junction points. 
     As can be concluded best from  FIG. 3 , the shoe body  12  is designed so that it is symmetrical with respect to a longitudinal center axis MA. This makes it possible to use an identical injection molding tool for a left and a right swimming shoe. 
     The details provided hereinafter refer to the  FIGS. 8 to 12  of the swimming shoe in accordance with the second embodiment. For purposes of simplifying the description, those components that correspond to the components of the first embodiment are assigned similar reference numbers, which are however prefixed by “1”. 
       FIG. 8  shows a perspective view of a swimming shoe  10  for the right foot in accordance with a second embodiment. As shown in  FIG. 8 , the swimming shoe  10  mainly consists of two parts, i.e. the actual shoe body  12  and a sole flap  114  shown separately in  FIG. 12 , which is connected with the shoe body  12  via a hinge coupling  18  still to be described in greater detail. The hinge coupling  18  has a flexible strap  120  by means of which the sole flap  114  is connected with the shoe body  12 , with the strap  120  flexibly pressing the sole flap  114  with pre-tension against a floor space  32  of the shoe body  12 . 
     In this embodiment, the strap  120  is again produced by injection molding as an integral part of the shoe body  12 . The shoe body  12  with the strap  120  is made of a thermoplastic elastomer, preferably a thermoplastic elastomer based on urethane (TPU). The sole flap is a synthetic injection molded part. 
     As shown in  FIGS. 8 and 10 , the section of the strap  120  projecting over the floor space is bent outward in the mounted state of the sole flap and is connected with the sole flap  114 . This is the swiveling section  130 , which can swivel with the leg kick along with the sole flap  114  due to water resistance. The section that does not project over the floor space  32  constitutes a not swiveling and/or non-swiveling section  128 , which is connected with the shoe body  12 . A swivel axis  116  of the hinge coupling  18  lies between the swiveling section  130  and the not-swiveling section  128 . The entire length of the strap can thus be used to provide the hinge function. 
     The strap  120  made of a piece of cloth has a uniform wall thickness and—depending on the material—a thickness din the range of 3 mm to 5 mm. 
       FIG. 9  shows a view of the swimming shoe  10  in accordance with the second embodiment as seen from below. The sole flap  114  has an outer section  122 , to which the swiveling section  130  of the strap  120  is attached, and an inner section  124 , which rests against the floor space  32  of the shoe body  12  when it is at rest. The sections  122  and  124  are separated from each other by the swivel axis  116 . 
     The nature of the connection between the strap  120  and the sole flap  114  in accordance with the second embodiment is described in greater detail below. 
     As shown in  FIG. 12 , the sole flap  114  has two rows of long holes, which respectively contain an inner oblong hole  50  and an outer oblong hole  52  in the transverse direction of the longitudinal direction of the shoe body. The swiveling section  130  of the strap  120  furthermore has two fastening tongues  142 . 
     The fastening tongue  142  is laced into the long holes so as to fasten the sole flap. More accurately, the fastening tongues  142  are respectively inserted from above into the appropriate inner long hole  50  and then from below into the corresponding outer long hole  52 . The fastening tongues  142  and thus the strap  120  can be loosely connected with the sole flap  114 . In the embodiment shown here, there are two drilled cutouts and/or drilled holes  161  on the outer section  122  of the sole flap  114  and two drilled cutouts and/or drilled holes  159  at an end section  143  of the fastening tongue  142  of the strap  120 , which are mutually aligned and can be respectively introduced into a nib and/or a stud. The cutouts  159 ,  161  are aligned with each other regarding their position, such that—as shown in  FIG. 10 —the sole flap  114  lies flat on the floor space  32 . The two connecting points are essentially located along the longitudinal direction of the swimming shoe  10 . 
     The resistance of the water can push the sole flap  114  along with the swiveling section  130  of the strap  120  to an angle of at most 90°, until a top side  48  of the end section  143  of the fastening tongue  142  strikes the shoe body  12 . 
     The swiveling section  130  furthermore has a pre-tensioning tongue  56 . The pre-tensioning tongue  56  is located between the two fastening tongues  142  and rests under bending pre-stress in a mounted state of the sole flap  114  against the top side  54  of the outer section  122  of the sole flap  114 . It is possible to do without fastening the pre-tensioning tongue  56  to the sole flap  114 . 
     In accordance with the embodiment shown here, the sole flap  114  furthermore has numerous ribs  144 . These ribs  144  are located at the bottom  147  of the sole flap  114  and extend across the longitudinal axis of the shoe body  12 . 
     As can best be concluded from  FIG. 10 , the shoe body  12  is positioned symmetrically with respect to a longitudinal center axis MA. It is in this way that it is possible to use the same injection molding tool for a left and a right swimming shoe. 
     A variant of the sole flap in accordance with  FIGS. 8 to 12  is hereinafter described in greater detail with reference to the  FIGS. 13 and 14 . For purposes of simplifying the description, those components that correspond to the components of the previously described second embodiment are assigned similar reference numbers in which the prefix “1” is replaced by “2”. 
     Deviating from the embodiment according to  FIGS. 8 to 12 , the sole flap  214 , which is preferably designed as an injection molded part, has a cutout  253 , over the approximate center of which a bridge  255  extends, in place of the long holes  50 ,  52 . The fastening tongues  142  not shown in greater detail and forming the outer strap segments can thus—as shown in  FIGS. 10 and 11 —be woven into the sole flap  214 . The reference number  261  refers to cutouts, which serve the purpose of taking up rivets by means of which the woven-in fastening tongues are connected with the sole flap  214 . The reference number  263  refers to a cutout for producing of a further riveted joint with the pre-tensioned tongue  56 , which takes care of an additional pre-tensioning force for pressing the sole flap against the floor space of the shoe body under flexible elastic pre-tension. 
     In further deviation from the embodiment according to  FIGS. 8 to 12 , the ribs  244  are installed on the side of the sole flap  214  facing the shoe body. A fixing flap  270  serving a cutout  272  for receiving a pushbutton connecting element not shown, with which the sole flap  214  can be affixed so that it is separable from the shoe body when the hinge function is deactivated is lastly fitted onto the sole flap  214  on the side opposite to the cutouts  253 . In this way, the sole flap can additionally be affixed to the shoe body by means of a separate holding device if the shoe is to be used outside of the water. The pushbutton connection can, for example, be implemented in a manner such as that, e.g., shown in FIG. 8 of the German patent DE 2007 003508 B3 or as described in the older German patent application DE 10 2015 101287 with reference to the  FIGS. 1 to 7 . The disclosure in these older patent applications of relevance here likewise becomes the subject of the present application by reference. 
     The strap  270  can be stowed away to save space in the “swimming mode”, which is suggested by the dash-dotted line in  FIG. 13 . A pushbutton connection, for which a cutout  274  is provided in the sole body  214 , can be used in this case as well. This configuration is achieved in that the folded up strap  270 ′, which is fixed in place via the pushbutton connection, does not extend over the ribs  244 , and in that the pushbutton connecting components also do not extend over the ribs, so that the sole flap  214  is pressed against the floor area of the shoe body without any gap, and neither the strap  270  nor the push-button connection is felt when walking with the shoe. 
     It can be deduced from the view of the sole flap  214  from below in accordance with  FIG. 14  that the bottom has numerous nubs  278 , which provide for a skid-proof hold when walking with the swimming shoe. It is furthermore evident that the cutouts  261 ,  263  and  274  are configured so that the pushbutton connecting components can be taken up in the sole body  214  in a positive locking and as far as possible recessed manner so that they do not show and do not impair the function of the sole flap  214 . 
     Experiments have shown that the construction of the swimming shoe of this invention with both embodiments ensures that heretofore unachievable long term functionality can be achieved via good user friendliness. In other words, the function supporting the leg kick of the person learning to perform the breast stroke is sustained for the long term via the simplified construction of the flexible strap. The swimming shoe can, at the same time, be kept relatively small, and the production of the swimming shoe is further simplified compared with past solutions. Due to the construction of the hinge design with the flexible strap, the sole flap in the non-swiveled condition remains safely in a neutral position near the shoe body, even when walking outside of the water, so that the hinge is treated with care and the risk of falling is reduced. The swimming shoe is lastly characterized by being comfortable to wear, particularly when walking with the swimming shoes on. 
     The production of the swimming shoe is described below. 
     In the first step, the shoe body ( 12 ) that is integrated with a left strap and a right strap, which respectively extend over a floor space ( 32 ) of a shoe body ( 12 ) with a swivel section ( 30 ;  130 ), is preferably produced by an injection molding process. As an alternative to the first step, the shoe body ( 12 ) can be produced with identical fastening sections for the separate strap ( 20 ;  120 ) on both of its sides, preferably by the injection molding process. The left strap or the right strap is cut off in the second step. As an alternative to the second step, the separate strap ( 20 ;  120 ) can be attached to the fastening section of the shoe body ( 12 ). At the end, the sole flap ( 14 ;  114 ) is attached to the swiveling section ( 30 ;  130 ), in that it is bent outward. The swimming shoe of this invention can be produced by this simplified production process. 
     Modifications of the embodiments shown are of course possible without departing from the basic concept of this invention. 
     The long-term functionality can be improved by different modifications based on the first embodiment. The material TPU can thus be replaced with other materials having similar physical characteristics. 
     The flexible strap also does not have to be of one piece with the shoe body. The non-swiveling section of the strap can, for example, be attached to the shoe body via a separable connection. The production process can accordingly be varied. The swimming shoe thus consists of three parts, i.e. of a shoe body, a strap and a sole flap, which can be used for both shoes, the left shoe and the right shoe. 
     An additional strap whose length is adjustable can, for example, be used for fastening the sole flap as described with reference to the FIGS. 6, 7, 9 and 10 of the German patent DE 2007 003508 B3. The relevant disclosure of the German patent DE 2007 003508 B3 is hereby expressly referred to in the present application. 
     The pin-like connection between the strap and the sole flap can also be established by means of an adhesive or a pushbutton connection. 
     The number of connecting points can of course also be varied. 
     It is possible to vary the number of rows of long holes and the number of fastening tongues based on the second embodiment. A row of long holes and fastening tongues or several sets of long holes and several fastening tongues can accordingly be installed. The number of pre-tensioning tongues can be also varied and can be zero or more than two. 
     The position of the strap can also be varied. In the embodiments described above the strap is located on the side wall of the shoe body. The strap can also be located within the side wall of the shoe body.