Abstract:
The present invention provides a stabilizing device that helps to prevent over-pronation or over-supination and a shoe which includes such a stabilizing device. The stabilizing device is provided along a side of the midsole and preferably extends laterally between about 20% and about 35% of a width of the sole towards the opposite side thereof. The stabilizing device includes an elongated portion and a sidewall portion that extends transversely from the elongated portion. The sidewall portion forms part of an outer peripheral wall of the shoe. The sidewall portion has a stiffness which varies along the length of the stabilizing device to provide a predetermined support profile along the side of the sole. The elongated portion can also vary in stiffness along its length. The stabilizing device can be formed of a resilient material using an injection molding procedure or similar technique.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional patent application Ser. No. 61/133,282, filed Jun. 26, 2008, the entirety of which is incorporated herein by reference thereto. 
     
    
     FIELD OF INVENTION 
       [0002]    This invention relates generally to a stabilizing element for a shoe, and a shoe containing said stabilizing device and, more specifically, to a stabilizing device for controlling the rolling motion of a wearer&#39;s foot over a foot strike path. 
       BACKGROUND 
       [0003]    The complex motions of the foot that can occur during a gait cycle of a wearer have been the focus of a multitude of biomechanical studies with a goal toward injury prevention and generally improved walking and running performance shoes. In particular, it has been an objective in the design of modern athletic shoes to provide support and cushioning where needed over a typical gait cycle. Typically, cushioning is provided in areas of a midsole of a shoe under the heel region to help minimize the impact of initial heel strike. Additional support elements are also typically provided to reduce excessive rolling of the foot toward the inner (medial) side or outer (lateral) side during a gait cycle by appropriate positioning of stiffening materials and structures. 
         [0004]    The tendency to roll toward the medial side after initial heel impact, or pronation, is a normal movement of the foot that occurs during walking or running. Immediately following the initial heel strike, the joint between the foot bones called the subtalar joint is unlocked, allowing pronation, a coordinated triplane motion of the foot, to occur during the forefoot lowering events of the loading period of the so-called stance phase. The triplane motions are: (1) abduction, in which the front of the foot is turned outwards at the subtalar joint and away from the line of progression of the wearer; (2) dorsiflexion, in which the front of the foot is angled upwards relative to the heel of the foot at the ankle, or talocrural joint; and (3) eversion, in which the sole of the foot is turned outward relative to the heel of the foot at the subtalar joint. With this coordinated combination of three planes of motions, the foot typically rolls from the lateral side toward the medial side of the foot as the medial aspect of the midfoot area of the foot comes into contact with the running surface. This triplane rolling of the foot as the wearer&#39;s body weight begins to move forward allows the foot to transfer some of the loading force to the waling or running surface. The foot remains in a pronated position throughout the mid-stance phase. 
         [0005]    Supination typically follows pronation. As one&#39;s body weight moves forward over the foot, the subtalar joint locks and a reversal of the events that occurred during the loading period occurs. Supination involves the motions of: (1) adduction, in which the locking of the subtalar joint allows the foot to turn inward toward the line of progression; (2) plantarflex, in which the forefoot is flexed downward relative to the heel at the ankle; and (3) inversion, in which the sole of the foot is turned inward at the subtalar joint relative to the heel. With the combination of these three motions, the foot continues rolling forward onto the toes. During motion through ball and toe contact, the foot rolls outward just before the toes start to leave the ground. The combination of these motions allows the foot to be converted from a mobile adaptor to a rigid lever, which is essential for the forward propulsion of the body. 
         [0006]    Though pronation and supination are natural motions, both excessive pronation, often caused by high pronation velocity, and excessive supination are undesirable and can lead to injury. Various approaches have been used in footwear design to control these rotational motions to avoid injury. Traditional so-called medial “post” or “posting” systems typically use a firmer density of ethylene vinyl acetate (“EVA”) or polyurethane (“PU”) foam on the medial side of a shoe in a rearfoot portion of a midsole to control pronation. However, it is difficult to control the density and hardness of such foams. For example, manufactured foams are often softer than specified in production. In addition, it takes more time and costs more to make the denser EVA foams. Such medial posts often use two densities of foam in a wedged configuration to provide a smoother transition for the foot as it rolls from heel to toe. However, both the relative density and thickness of these foams are difficult to control during manufacturing, and the positioning of a wedge of rigid foam over a softer foam does not provide a truly continuous transition of stiffness from heel strike to toe-off. 
         [0007]    Prior devices address motion control primarily by altering compression resistance underneath the foot using discrete rigid posts and plates or dual density midsole foams. The prior devices provide little or no transition of compression resistance. In addition, such transition is offered only under the foot and in only one direction—transverse to the longitudinal axis of the shoe. None of the prior devices discloses or suggests a device for precisely and smoothly controlling the motion of the foot along a foot strike path or providing a continuous transition in compression resistance as the foot traverses a strike path. 
         [0008]    Accordingly, there is a need, which has not been adequately addressed in the prior art, for a device for precisely and smoothly controlling the motion of a foot along a foot strike path and that also provides a continuous and smooth transition in compression resistance along the foot strike path. 
       SUMMARY OF THE INVENTION 
       [0009]    A stabilizing device of the present invention addresses the deficiencies of the prior art by precisely and smoothly controlling the motion of the foot along a foot strike path by providing a continuous variation in stiffness along a medial or lateral side of a wearer&#39;s foot. A shoe sole and a shoe which include the stabilizing device are also formed in accordance with the present invention. 
         [0010]    In one embodiment, a stabilizing device for use in a shoe sole has a first end and a second end. The first end is adapted to be mounted in the rearfoot region of the shoe and the second end is adapted to be mounted in the arch region of the shoe. The stabilizing device has an elongated portion positioned between the first end and the second end that will extend along a periphery of a shoe sole from the rearfoot region into the arch region. The stabilizing device also has a sidewall portion that extends from the rearfoot region into the arch region. The sidewall portion extends transversely from the elongated portion along the length of the elongated portion. The sidewall portion is adapted for forming a portion of a peripheral wall on either the medial or lateral side of the shoe. The sidewall portion has a stiffness that varies continuously from the first end toward the second end. 
         [0011]    In one embodiment, the stiffness of the sidewall portion decreases continuously from the first end toward the second end. In another embodiment, the stiffness of the sidewall portion increases continuously from the first end toward the second end. 
         [0012]    In another embodiment the cross-sectional area formed from the sidewall portion and the elongated portion varies continuously from the first end toward the second end. In accordance with this embodiment, the cross-sectional area can also decrease continuously from the first end toward the second end. In another embodiment, the cross-sectional area increases continuously from the first end toward the second end. 
         [0013]    In a further embodiment, a stiffness of the elongated portion varies continuously from the first end toward the second end. In accordance with this embodiment, the stiffness of the elongated portion can also decrease continuously from the first end toward the second end. In another embodiment, the stiffness of the elongated portion increases continuously from the first end toward the second end. 
         [0014]    In still another embodiment, the stabilizing device is adapted to extend from either the medial or lateral side of the shoe across 20% to 35% of the width of the shoe at the arch region. 
         [0015]    In one embodiment, the elongated portion has a surface adapted for being positioned flush with an upper surface of the shoe sole. 
         [0016]    In another embodiment, the sidewall portion has a lower portion that is adapted to extend from the elongated portion towards a ground engaging surface of the shoe. In accordance with this embodiment, a lower extension portion can also extend transversely from an end of the lower portion of the sidewall portion away from the elongated portion. 
         [0017]    The stabilizing device of the above embodiments may be integrally formed of a thermoplastic material. The thermoplastic material may be injection molded thermoplastic. 
         [0018]    In one embodiment, the stabilizing device of any of the above embodiments is adapted to be positioned along the medial side of the shoe. In another embodiment, the stabilizing device is adapted to be positioned along the lateral side of the shoe. 
         [0019]    The stabilizing device may further include an extended heel portion. The extended heel portion includes an extended elongated portion. The extended elongated portion is integrally connected to the elongated portion of the stabilizing device. The extended heel portion also includes an extended sidewall portion. The extended sidewall portion is integrally connected to the sidewall portion of the stabilizing device. The extended sidewall portion has a stiffness that varies continuously. The extended heel portion is adapted to extend from one the medial or later side of the shoe, around the heel end of the shoe, to the other of the medial or lateral side of the shoe. 
         [0020]    In one embodiment, the stiffness of at least one of the extended sidewall portion and the extended elongated portion increases continuously along the medial and lateral sides toward the rear of the extended heel portion. In another embodiment, the stiffness of at least one of the extended sidewall portion and the extended elongated portion decreases continuously along the medial and lateral sides toward the rear of the extended heel portion. 
         [0021]    A shoe formed in accordance with the present invention includes a stabilizing device. The shoe has an upper and a shoe sole. The stabilizing device is disposed along either the medial or lateral side of the shoe sole. The stabilizing device has a first end and a second end. The first end is mounted in the rearfoot region of the shoe and the second end is mounted in the arch region of the shoe. The stabilizing device has an elongated portion positioned between the first end and the second end that extends along a periphery of the shoe sole from the rearfoot region into the arch region. The stabilizing device also has a sidewall portion that extends from the rearfoot region into the arch region. The sidewall portion extends transversely from the elongated portion. The sidewall portion forms a portion of a peripheral wall on either the medial or lateral side of the shoe. The sidewall portion has a stiffness that varies continuously from the first end toward the second end. 
         [0022]    In one embodiment, the stiffness of the sidewall portion decreases continuously from the first end toward the second end. In another embodiment, the stiffness of the sidewall portion increases continuously from the first end toward the second end. 
         [0023]    In another embodiment the cross-sectional area formed from the sidewall portion and the elongated portion varies continuously from the first end toward the second end. In accordance with this embodiment, the cross-sectional area can decrease continuously from the first end to the second end. In another embodiment, the cross-section area increases continuously from the first end to the second end. 
         [0024]    In a further embodiment, a stiffness of the elongated portion varies continuously from the first end toward the second end. In accordance with this embodiment, the stiffness of the elongated portion can decrease continuously from the first end toward the second end. In another embodiment, the stiffness of the elongated portion increases continuously from the first end toward the second end. 
         [0025]    In still another embodiment, the stabilizing device extends from either the medial or lateral side of the shoe across 20% to 35% of the width of the shoe at the arch region. 
         [0026]    In one embodiment, the elongated portion has a surface positioned flush with an upper surface of the shoe sole. 
         [0027]    In another embodiment, the sidewall portion has a lower portion that extends from the elongated portion towards a ground engaging surface of the shoe. In accordance with this embodiment, a lower extension portion can also extend transversely towards the center of the shoe sole from an end of the lower portion away from the elongated portion. 
         [0028]    The stabilizing device of the above embodiments can be integrally formed of a thermoplastic material. The thermoplastic material can be injection molded thermoplastic. 
         [0029]    In one embodiment, the stabilizing device is positioned along the medial side of the shoe. In another embodiment, the stabilizing device is positioned along the lateral side of the shoe. 
         [0030]    The stabilizing device may further include an extended heel portion. The extended heel portion includes an extended elongated portion. The extended elongated portion is integrally connected to the elongated portion of the stabilizing device. The extended heel portion also includes an extended sidewall portion. The extended sidewall portion is integrally connected to the sidewall portion of the stabilizing device. The extended sidewall portion has a stiffness that varies continuously. The extended heel portion extends from one the medial or later side of the shoe, around the heel end of the shoe, to the other of the medial or lateral side of the shoe. 
         [0031]    In one embodiment, the stiffness of at least one of the extended sidewall portion and the extended elongated portion increases continuously along the medial and lateral sides toward the rear of the extended heel portion. In another embodiment, the stiffness of at least one of the extended sidewall portion and the extended elongated portion decreases continuously along the medial and lateral sides toward the rear of the extended heel portion. 
         [0032]    When positioned on a medial side of the shoe, the stabilizing device reduces pronation velocity of the subtalar joint by providing a precisely controlled stiffness that continuously decreases from the rearfoot region to the arch region along the longitudinal axis and on the medial side of the shoe. When positioned on a lateral side of the shoe, the stabilizing device reduces supination velocity of the subtalar joint by providing a precisely controlled stiffness that continuously decreases from the rearfoot region to the arch region along the longitudinal axis on the lateral side of the shoe. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIGS. 1A and 1B  are side views of the medial and lateral sides respectively of a skeleton of a human foot. 
           [0034]      FIG. 2  is a perspective view of an embodiment of a stabilizing device. 
           [0035]      FIG. 3  is a cross-sectional view of the stabilizing device of  FIG. 2 . 
           [0036]      FIG. 4  is a schematic top view of an embodiment of a shoe sole with the stabilizing device of  FIG. 2  positioned on a medial side of a shoe. 
           [0037]      FIG. 5  is a medial side view of the shoe sole and motion control device of  FIG. 4 . 
           [0038]      FIG. 6  is a cross-sectional view of the shoe sole and stabilizing device of  FIG. 4   
           [0039]      FIG. 7  is a medial side view of another embodiment of a shoe sole with another embodiment of a stabilizing device. 
           [0040]      FIG. 8  is a cross-sectional view of the shoe sole and motion control device of  FIG. 7 . 
           [0041]      FIG. 9  is a schematic top view of an embodiment of a shoe sole with an embodiment of a stabilizing device on the medial side and an embodiment of a stabilizing device on the lateral side. 
           [0042]      FIG. 10  is a schematic top view of an embodiment of a shoe sole with an embodiment of a stabilizing device with an extended heel portion. 
           [0043]      FIG. 11  is a schematic top view of an embodiment of a shoe sole with an embodiment of a stabilizing device with an extended heel portion. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]      FIGS. 1A and 1B  show a medial and lateral side view, respectively, of the skeleton of a human foot  100 . The forefoot region  101  of a foot corresponds generally with the phalanges (toes)  102  and metatarsals  103 . The rearfoot region  104  of the foot, also referred to as the heel region, corresponds generally to the calcaneous bone  105 . The arch region of the foot generally overlaps a portion of the forefoot including the metatarsals  103  (but not the phalanges  102 ) and encompasses the tarsals  107  in between the calcaneous bone  105  and the metatatarsals  103 . Referring to  FIG. 1A , a medial longitudinal arch region  107  is formed between the medial tubercle of calcaneous  105  to the head of the first, second and third metatarsals  103 - 1 ,  103 - 2 ,  103 - 3 . As shown in  FIG. 1B , a longitudinal arch region  106  on the lateral side of the foot  100  is formed generally between the lateral tubercle of the calcaneous  105  to the head of the fourth  103 - 4  and fifth metatarsals  103 - 5 . The regions of a shoe sole are generally divided into relative sections to correspond generally to these regions of the human foot, with the heel or rearfoot region of a shoe sole generally known as the area corresponding to the calcaneous bone  105 , and the forefoot region of a shoe sole corresponding to the area underlying at least the phalanges  102 . The arch region of a shoe sole may be formed to encompass the entire anatomical arch of a foot, particularly for use in sports creating high stress on the arches of the foot. Herein, we refer to an arch region of a shoe sole as encompassing the area forward of the rearfoot region and including the metatarsals  103 . 
         [0045]    Referring to  FIGS. 2 and 3 , an embodiment of a stabilizing device  201  for use in a shoe is made from a unitary piece of material, such as plastic. The stabilizing device  201  has a first end  202  and a second end  203  for mounting the device in a shoe. The first end  202  is adapted for mounting in the rearfoot region of a shoe. The second end  203  is adapted for mounting in the arch region of a shoe. The stabilizing device  201  includes an elongated portion  204  that is positioned between the first end  202  and the second end  203 . In one embodiment, the first end  202  for mounting corresponds to an end of the elongated portion  204  and the second end  203  for mounting corresponds to the other end of the elongated portion  204 . 
         [0046]    The stabilizing device  201  also includes a sidewall portion  205  that extends transversely from the elongated portion  204  along the length of the elongated portion  204  and preferably beyond. The sidewall portion  205  is adapted to form a portion of an outer peripheral wall on either the medial or lateral side of the shoe in which it is positioned. The sidewall portion  205  has a stiffness that varies continuously from the first end  202  toward the second end  203 . In one embodiment, the stiffness of the sidewall portion  205  decreases continuously from the first end  202  toward the second end  203 . In another embodiment, the stiffness of the sidewall portion  205  increases continuously from the first end  202  toward the second end  203 . 
         [0047]    The elongated portion  204  is adapted for mounting no further forward than the arch region of the shoe. By restricting the elongated portion  204  of the stabilizing device  201  to the arch and heel region, the phalanges  102  of the foot  100  are allowed to flex while the wearer is walking or running, which assists in pushoff and enables more efficient movement. 
         [0048]    In addition to varying the stiffness of the sidewall portion  205 , the stiffness of the elongated portion  204  can also be varied continuously from the first end  202  toward the second end  203 . In one embodiment, the stiffness of the elongated portion  204  decreases continuously from the first end  202  toward the second end  203 . In another embodiment, the stiffness of the elongated portion  204  increases continuously from the first end  202  toward the second end  203 . 
         [0049]    In order to control the stiffness of the sidewall portion  205  and/or the elongated portion  204 , the cross-sectional area formed from the sidewall portion  205  and the elongated portion  204  can be varied continuously from the first end  202  toward the second end  203 . In one embodiment, this cross-sectional area decreases continuously from the first end  202  toward the second end  202 . In another embodiment, this cross-section area increases continuously from the first end  202  toward the second end  203 . 
         [0050]    In another embodiment, the sidewall portion  205  has a lower portion  207  that is adapted to extend from the elongated portion  204  towards a ground engaging surface of the shoe. In yet another embodiment, as best shown in  FIG. 3 , a lower extension portion  208  extends preferably transversely along the length of the end of the lower portion  207  of the sidewall portion  205  away from the elongated portion  204 . The lower extension portion  208  is adapted to be mounted into or between two layers of the sole of the shoe. 
         [0051]    The stabilizing device  201  is adapted to be positioned along the medial side of the shoe or along the lateral side of the shoe. Referring to  FIG. 4 , when positioned on a medial side of the shoe, the stabilizing device  201  reduces pronation velocity of the subtalar joint by providing a precisely controlled stiffness that continuously decreases from the rearfoot region  224  to the arch region  226 . In a different embodiment, the stabilizing device  201  can be positioned along the medial side of the shoe and formed so that its stiffness increases continuously from the rearfoot region to the arch region. When positioned on a lateral side of the shoe, the stabilizing device  201  reduces supination velocity of the subtalar joint by providing a precisely controlled stiffness that continuously increases from the rearfoot region to the arch region. In another embodiment, the stabilizing device  201  can be positioned along the lateral side of the shoe and formed with a stiffness that decreases continuously from the rearfoot region  224  to the arch region  226 . 
         [0052]      FIGS. 4 ,  5 , and  6  depict a shoe sole  200  containing the stabilizing device  201 . A shoe formed in accordance with the present invention can include an upper and the shoe sole  200 . The stabilizing device  201  is disposed along either the medial or lateral side of the shoe sole  200 . The first end  202  of the stabilizing device  201  is mounted in the rearfoot region  104  of the shoe sole  200 . The second end  203  of stabilizing device  201  is mounted in the arch region  106  of the shoe sole  200 . The sidewall portion  205  of the stabilizing device  201  preferably forms a portion of a peripheral wall  209  on either the medial or lateral side of the shoe sole  200 . In addition, the elongated portion  204  has an upper surface  206  that can be positioned flush with an upper surface  212  of the shoe sole  200 . 
         [0053]    In one embodiment, the lower portion  207  of the sidewall portion  205  extends from the elongated portion  204  towards a ground engaging surface  210  of the shoe sole  200 . A lower extension portion  208  extends transversely from the lower portion  207 . The lower extension portion  208  can be mounted between two layers of the shoe sole  200 , for example, ground engaging surface  209  and midsole  210 , as shown in  FIG. 6 . 
         [0054]    In one embodiment, shown in  FIG. 9 , a stabilizing device  201  adapted to be a medial device and a stabilizing device  201  adapted to be a lateral stabilizing device are positioned on the medial and lateral sides respectively in the same shoe  200 . 
         [0055]    The elongated portion  204  of the stabilizing device  201  extends along a periphery of the shoe  200  and extends from either the medial side or the lateral side of the shoe toward, but not past, the longitudinal centerline of the shoe. In other embodiments, the stabilizing device  201  also extends along the peripheral rear of the shoe, encompassing the heel ( FIGS. 9-11 ). In one embodiment, the stabilizing device  201  extends from either the medial or lateral side of the shoe sole  200  across between 15% to 40% of the shoe sole  200  at the narrowest cross section of the sole  200 . Most preferably, the device  201  extends across 20% to 35% of the width of the shoe sole  200  at the narrowest cross section of the sole  200 . 
         [0056]    One end  202  of the elongated portion  204  is positioned in the rearfoot region of the shoe  200 . In one embodiment, the first end  202  is adapted to be positioned in a portion of the sole situated below the talus bone of the wearer&#39;s foot. In another embodiment, the first end  202  is located a distance from the rear end  216  of the shoe  200  that is between about 5% and 35% of the length of the shoe. Most preferably the distance is between about 10% and 20%. In another embodiment, the distance is between about 12% and 18%. 
         [0057]    The second end  203  is positioned in the arch region of the shoe  200 . For a stabilizing device  201  located on a medial side of the shoe  200 , the second end  203  is preferably located a distance from the rear end  216  of the shoe  200  that is between about 50% and 80% of the length of the shoe. Most preferably, the distance is between about 60% to 75% of the length of the shoe. For a stabilizing device  201  located on the lateral side of the shoe  200 , the second end  203  is preferably located a distance from the rear end  216  of the shoe that is between about 50% and 80% of the length of the shoe  200 . Most preferably the distance is between about 60% to 75% of the length of the shoe  200 . 
         [0058]      FIGS. 7 and 8  show an alternative embodiment of a stabilizing device  701  and a shoe sole  700  containing the stabilizing device  701 . The stabilizing device  701  is made from a unitary piece of material, such as plastic. The stabilizing device  701  includes an elongated portion  704  that extends from a first end  702  positioned in the rearfoot to a second end  703  positioned in the arch region. The stabilizing device  701  also includes a sidewall portion  705  that extends between the first end  702  and the second end  703 . The sidewall portion  705  extends transversely from the elongated portion  704  along the length of the elongated portion  704 . The sidewall portion  705  preferably forms a portion of an outer peripheral wall  709  on either the medial or lateral side of the shoe sole  700  in which it is positioned. The stiffness and cross-sectional area of the sidewall portion  705  and elongated portion  704  are varied as described above with respect to  FIGS. 2-6  in accordance with at least one of the embodiments described. 
         [0059]    As compared with the stabilizing device  201  shown in  FIG. 4 , the sidewall portion  705  of the stabilizing device  701  does not contain a lower portion  207  or a lower extension portion  208 . The elimination of the lower portion  207  of the continuous sidewall  704  lessens the stiffening caused when this lower portion  207  is present and offers greater overall control of the stiffness profile of the motion control device  701 . 
         [0060]      FIG. 10  shows an alternate embodiment of the stabilizing device of the present invention. The stabilizing device  301  includes an extended heel portion  213 . The extended heel portion  213  is integrally extended from a stabilizing device  201  positioned on at least one of a medial and lateral side. In  FIG. 10 , the stabilizing device  301  includes both a medial and lateral stabilizing device  201 , however a stabilizing device including an extended heel portion  213  connected to only one of a lateral or medial stabilizing device  201  is also contemplated. The extended heel portion  213  is located in the rearfoot region  224  of the sole and includes an extended elongated portion  214  that is integrally connected to the elongated portion  204  of the stabilizing device  201 . The elongated portions extend into the arch region  226 . The extended heel portion  213  also includes an extended sidewall portion  215  that is integrally connected to the sidewall portion  205  of the stabilizing device  201 . The extended heel portion  213  is adapted to be positioned in the rearfoot portion of the shoe  200 . It is adapted to extend from the medial side of the shoe, around the heel portion of the shoe, to the lateral side of a shoe  300 . 
         [0061]    In one embodiment, the stiffness of the extended sidewall portion  215  or the extended elongated portion  214 , or both increases continuously along the medial and lateral sides toward the rear of the extended heel portion  213 . In another embodiment, the stiffness of the extended sidewall portion  215 , the extended elongated portion  214 , or both decreases continuously along the medial and lateral sides toward the rear  216  of the extended heel portion  213 . 
         [0062]      FIG. 11  shows another embodiment of a stabilizing device  401  mounted in a shoe  400  with an extended heel portion  213  wherein the elongated portion  204  and sidewall portion  205  are positioned along both the medial and lateral sides of the shoe  400 . The extended elongated portion  214  is integrally formed with elongated portions  204  located on both the medial and the lateral side. The extended sidewall portion  215  is integrally formed with the sidewall portions  205  on the medial and lateral sides. In this embodiment, the sidewall portions extend into the forefoot region. 
         [0063]    As can be seen most clearly in  FIG. 3 , the stabilizing device of the present invention is preferably formed as a monolithic seamless piece, with the elongated portion ( 204 ,  704 ) gradually curving upward to blend into the upper portion of the sidewall portion ( 205 ,  705 ). Preferably, the stabilizing device of the present invention is formed using an injection molding process that allows precise formation of a predetermined continuously and smoothly varying stiffness profile. The stabilizing device is preferably formed of a thermoplastic material, most preferably, a soft thermoplastic injection molded material, such as thermoplastic polyurethane (“TPU”). However, any other material which exhibits well-defined stiffness and resilience properties can also be used, which can be precisely formed into a device having a predetermined continuously and smoothly varying stiffness profile. 
         [0064]    The stiffness of the stabilizing devices of the present invention can be directionally varied as needed by changing the thickness of the thermoplastic material. Accordingly, forces created on the shoe by a wearer&#39;s foot striking the ground will impact on different thicknesses in various directions along the foot strike path. Regions of thicker material will have a higher stiffness and are positioned where greater resistance is needed compared to thinner regions. In this way, the stabilizing device can be precisely shaped and formed to provide a continuous stiffness profile along a side of a shoe to control the motion of a wearer&#39;s foot along a foot strike path and a smooth transition in resistance as the foot rolls from its lateral side on heel strike toward the medial side prior to toe-off. 
         [0065]    It is also contemplated that the density of the thermoplastic material itself can be varied to control the stiffness of the stabilizing device of the present invention. One skilled in the art will appreciate that a combination of density and thickness can also be precisely varied to form a stabilizing device having the desired continuous stiffness profile. Accordingly, the stabilizing device of this invention can be formed with any stiffness profile to provide a continuously varying stiffness in any direction to control the motion of a wearer&#39;s foot along a predetermined foot strike path. 
         [0066]    Though in the embodiments shown, the stabilizing device is positioned in a midsole of the shoe, it is understood that the device can be adapted for mounting in any part or parts of a sole of a shoe, which may include an insole, an outsole, a midsole, or any combination of the foregoing. Generally, the stabilizing device is adapted for positioning anywhere below a plane of a wearer&#39;s foot with a sidewall extending above the sole and along the side of a wearer&#39;s foot. The sidewall preferably extends along a portion of an upper of the shoe. 
         [0067]    Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention and claims are not limited to those precise embodiments, and that various other changes and modifications may be applied therein by one skilled in the art without departing from the scope or spirit of the invention. As will also be apparent to those skilled in the art, various combinations of the embodiments and features taught in the foregoing description are possible and can result in preferred executions of the present invention. Accordingly, it is intended that such changes and modifications fall within the scope of the present invention as defined by the claims appended hereto.