Patent Publication Number: US-2023142549-A1

Title: Sole structure for article of footwear

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Pat. Application 63/276,182, filed on Nov. 5, 2021, the entire contents of which is hereby incorporated by reference, for any and all purposes. 
    
    
     REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
    
    
     SEQUENCE LISTING 
     Not applicable 
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to a sole structure for an article of footwear with a flexible forefoot region to provide for improved traction. The forefoot region of the sole structure includes an upper plate that is coupled to a lower plate (i.e., an outsole) by a beam. The beam is oriented along a heel-to-toe direction (i.e., a length of the sole structure) to allow the lower plate and the upper plate to pivot in both of a lateral direction and a medial direction (e.g., about a longitudinal axis of the article of footwear). Additionally, a midsole surrounds the beam and extends between the upper and lower plates to provide a resistive force that opposes the relative rotation between the upper and lower plates. The midsole can be tuned to provide a desired amount of resistance, which may be different on each of the medial and lateral sides. 
     2. Description of the Background 
     Many conventional shoes or other articles of footwear generally comprise an upper and a sole attached to a lower end of the upper. Conventional shoes further include an internal space (i.e., a void or cavity) which is created by interior surfaces of the upper and sole that receives a foot of a user before securing the shoe to the foot. The upper generally extends upward from the sole and defines an interior cavity that completely or partially encases a foot. In most cases, the upper extends over instep and toe regions of the foot, and across medial and lateral sides thereof. Many articles of footwear may also include a tongue that extends across the instep region to bridge a gap between edges of medial and lateral sides of the upper, which define an opening into the cavity. The tongue can be disposed below a lacing or other closure system and between medial and lateral sides of the upper, to allow for adjustment of shoe tightness. The tongue may be manipulable by a user to permit entry or exit of a foot from the internal space or cavity. In addition, the lacing system may allow a user to adjust certain dimensions of the upper or the sole, thereby allowing the upper to accommodate a wide variety of foot types having varying sizes and shapes. 
     The upper may comprise a wide variety of materials, which may be chosen based on one or more intended uses of the shoe. The upper may also include portions comprising varying materials specific to a particular area of the upper. For example, added stability may be desirable at a front of the upper or adjacent a heel region so as to provide a higher degree of resistance or rigidity. In contrast, other portions of a shoe may include a soft woven textile to provide an area with stretch-resistance, flexibility, air-permeability, or moisture-wicking properties. 
     The sole is attached to a lower surface or boundary of the upper and is positioned between the upper and the ground. As a result, the sole typically provides stability and cushioning to the user when the shoe is being worn. In some instances, the sole may include multiple components, such as an outsole, a midsole, and an insole. The outsole may provide traction to a bottom surface of the sole, and the midsole may be attached to an inner surface of the outsole and may provide cushioning or added stability to the sole. For example, a sole may include a particular material or be configured in a particular shape that may increase stability at one or more desired locations along the sole, or that may reduce stress or impact energy on the foot or leg when a user is running, walking, or engaged in another activity. 
     Sole assemblies generally extend between a ground surface and the upper. In some examples, the sole assembly includes an outsole that provides abrasion-resistance and traction with the ground surface. The outsole may be formed from rubber or other materials that impart durability and wear-resistance, as well as enhancing traction with the ground surface. 
     However, while many currently available shoes have varying features related to the above-noted properties, many shoes, including athletic shoes and hiking shoes, have sole structures with bottom surfaces that are generally inflexible along a width of the sole structure (e.g., a direction extending between lateral and medial sides of the sole structure). That is, while a sole structure may offer some flexibility due to the cushioning properties of a midsole, for example, when running along a curve or over an uneven or sloped surface, a substantial portion of an outsole may remain angled to and, therefore, not in contact with the ground. As a result, the contact patch between the outsole and ground is reduced and, correspondingly, traction is also reduced. To increase traction in these types of scenarios, a user may intentionally pronate or supinate to place the outsole approximately in parallel with the ground to increase traction. Intentional pronation and supination by a user, especially when under increased loading during physical activity, can increase the possibility of injury and reduce athletic performance. 
     Therefore, articles of footwear having features that aid in stability and traction are desired. These and other deficiencies with the prior art are outlined in the following disclosure. 
     SUMMARY 
     A number of advantages of the articles of footwear described herein will be apparent to those having ordinary skill in the art. For example, an article of footwear can include an outsole configured as a lower plate, which can be pivotably connected with an upper plate by a beam. The lower plate and the upper plate can be spaced apart from one another by the beam and a midsole, which can surround the beam to provide a resistive force that opposes the movement (i.e., rotation) between the lower and upper plates about the beam. 
     According to one aspect, the present disclosure provides a sole structure for an article of footwear having an upper and defining a forefoot region, a midfoot region, and a heel region. The sole structure can include a first plate and a second plate. The first plate can extend from the forefoot region, through the midfoot region, to the heel region, and can be configured to couple to the upper. The second plate is disposed within the forefoot region and can be spaced from the first plate by a gap, the second plate being disposed within the forefoot region. A beam can extend between the first plate and the second plate so that the first plate is pivotally coupled to the second plate by the beam. 
     In some embodiments, the beam can be configured as a linear beam that is aligned along a longitudinal axis of the sole structure. The beam can define a length that is parallel to the longitudinal axis, a width that is perpendicular to the length in a lateral-to-medial direction, and a height between the first plate and the second plate that is perpendicular to both the length and the width. The length can be greater than the at least one of the width or the height. In some cases, the beam can have a rectangular cross-section taken perpendicular to the length. 
     In some embodiments, the sole structure can further include a midsole that can be disposed between the first plate and the second plate. The midsole can include a first midsole portion positioned along a lateral side of the beam and a second midsole portion positioned along a medial side of the beam. The first midsole portion can be a first cushioning member having a first density and can be coupled to at least one of the first plate or the second plate. The second midsole portion can be a second cushioning member having a second density that can be different from the first density, and can be coupled to at least one of the first plate or the second plate. 
     In some cases, the midsole can further include a third midsole portion that can be coupled to the first plate in the heel region, opposite the upper. The third midsole portion can be spaced from the first midsole portion and the second midsole portion by a gap, which can extend from a lateral side to a medial side in the midfoot region. 
     In some embodiments, the beam can be integrally formed with at least one of the first plate or the second plate. The second plate can be configured as an outsole that can include at least one ground engaging element extending from a bottom surface of the second plate. 
     In some embodiments, the beam can be configured to allow the first plate and the second plate to pivot by a first maximum angular rotation in a first direction and by a second maximum angular rotation in a second direction. Each of the first maximum angular rotation and the second maximum angular rotation can be between about 10 degrees and about 30 degrees. In some cases, the first maximum angular rotation can be different from the second maximum angular rotation. 
     According to another aspect, the present disclosure provides a sole structure for an article of footwear having an upper and defining a forefoot region, a midfoot region, and a heel region. The sole structure can include an upper plate and a lower plate that can be spaced from and pivotably coupled with the upper plate by a beam. The beam can be configured to allow the upper plate and lower plate to rotate relative to one another toward each of a lateral side and a medial side of the sole structure. A first midsole portion can be disposed on the lateral side of the beam. The first midsole portion can be coupled to each of the upper plate and the lower plate so that the relative rotation of the upper plate and the lower plate causes the first midsole portion to deform. The deformation of the first midsole portion can provide a first resistive force that opposes the relative rotation of the upper and lower plates. A second midsole portion can be disposed on the medial side of the beam. The second midsole portion can be coupled to each of the upper plate and the lower plate so that the relative rotation of the upper plate and the lower plate causes the second midsole portion to deform. The deformation of the second midsole portion can provide a second resistive force that opposes the relative rotation of the upper and lower plates. 
     In some embodiments, each of the lower plate, the first midsole portion, and the second midsole portion can extend from a first end in the forefoot region to a second end in the midfoot region. In some cases, the beam can be aligned along a longitudinal axis of the sole structure and can be disposed entirely within the forefoot region. The beam can be configured to allow the upper plate and the lower plate to rotate relative to one another by a maximum angular rotation that can be between about 15 degrees and about 35 degrees. 
     According to yet another aspect, the present disclosure provides a sole structure for an article of footwear having an upper and defining a forefoot region, a midfoot region, and a heel region. The sole structure can include an upper plate that can be configured to couple to the upper and that can extend from the forefoot region, through the midfoot region, to the heel region. A forefoot portion can be positioned predominately in the forefoot region and a heel portion positioned predominately in the forefoot region, and the forefoot portion and the heel portion can be spaced apart from one another by a gap in the midfoot region. The forefoot portion can include a first lower plate that can be spaced from and pivotably coupled with the upper plate by a beam. The beam can be configured to allow the upper plate and lower plate to rotate relative to one another toward each of a lateral side and a medial side of the sole structure. A first midsole portion can be positioned between the upper plate and the first lower plate. The first midsole portion can at least partially surround the beam, such that the first midsole portion includes a lateral midsole portion positioned along a lateral side of the beam and a medial midsole portion disposed along a medial side of the beam. The heel portion can include a second lower plate and a second midsole member than can be positioned between the upper plate and the second lower plate. 
     In some embodiments, the lateral midsole portion and the medial midsole portion can each be coupled to both the upper plate and the first lower plate. 
     In some embodiments, the first lower plate can be configured as a first outsole portion and the second lower plate can be configured as a second outsole portion. 
     Other aspects of the articles of footwear described herein, including features and advantages thereof, will become apparent to one of ordinary skill in the art upon examination of the figures and detailed description herein. Therefore, all such aspects of the articles of footwear are intended to be included in the detailed description and this summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a top, front, and lateral perspective view of a sole structure for an article of footwear according to aspects of the disclosure; 
         FIG.  2    is a lateral side view of the sole structure of  FIG.  1    with an upper of the article of footwear shown in phantom; 
         FIG.  3    is a medial side view of the sole structure of FIG. with an upper of the article of footwear shown in phantom; 
         FIG.  4    is a top plan view of the sole structure of  FIG.  1   ; 
         FIG.  5    is a cross sectional view of the sole structure of  FIG.  1    taken along line A-A; 
         FIG.  6    is a cross sectional view of the sole structure of  FIG.  5    with the sole structure being compressed along a lateral side; and 
         FIG.  7    is a cross-sectional view of another sole structure with the sole structure being compressed along a lateral side. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The following discussion and accompanying figures disclose various embodiments or configurations of a shoe having an upper and a sole structure. Although embodiments are disclosed with reference to a sports shoe, such as a running shoe, tennis shoe, basketball shoe, etc., concepts associated with embodiments of the shoe may be applied to a wide range of footwear and footwear styles, including basketball shoes, cross-training shoes, football shoes, golf shoes, hiking shoes, hiking boots, ski and snowboard boots, soccer shoes and cleats, walking shoes, and track cleats, for example. Concepts of the shoe may also be applied to articles of footwear that are considered non-athletic, including dress shoes, sandals, loafers, slippers, and heels. 
     The term “about,” as used herein, refers to variations in the numerical quantity that may occur, for example, through typical measuring and manufacturing procedures used for articles of footwear or other articles of manufacture that may include embodiments of the disclosure herein; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients used to make the compositions or mixtures or carry out the methods; and the like. Throughout the disclosure, the terms “about” and “approximately” refer to a range of values ± 5% of the numeric value that the term precedes. 
     Also as used herein, unless otherwise limited or defined, “or” indicates a non- exclusive list of components or operations that can be present in any variety of combinations, rather than an exclusive list of components that can be present only as alternatives to each other. For example, a list of “A, B, or C” indicates options of: A; B; C; A and B; A and C; B and C; and A, B, and C. Correspondingly, the term “or” as used herein is intended to indicate exclusive alternatives only when preceded by terms of exclusivity, such as “only one of,” or “exactly one of.” For example, a list of “only one of A, B, or C” indicates options of: A, but not B and C; B, but not A and C; and C, but not A and B. In contrast, a list preceded by “one or more” (and variations thereon) and including “or” to separate listed elements indicates options of one or more of any or all of the listed elements. For example, the phrases “one or more of A, B, or C” and “at least one of A, B, or C” indicate options of: one or more A; one or more B; one or more C; one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C. Similarly, a list preceded by “a plurality of” (and variations thereon) and including “or” to separate listed elements indicates options of multiple instances of any or all of the listed elements. For example, the phrases “a plurality of A, B, or C” and “two or more of A, B, or C” indicate options of: one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C. 
     Further, as used herein, unless otherwise defined or limited, directional terms are used for convenience of reference for discussion of particular figures or examples. For example, references to “downward,” or other directions, or “lower” or other positions, may be used to discuss aspects of a particular example or figure, but do not necessarily require similar orientation or geometry in all installations or configurations. 
     The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections. These elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example configurations. 
     The present disclosure relates to an article of footwear with a sole structure attached to an upper. The sole structure includes an upper plate that is coupled to the upper and outsole that is configured as a lower plate, which defines a bottom of the article of footwear. The upper plate and the lower plate can be spaced from and pivotably coupled with one another by a beam defining a length that is approximately parallel to a length of the article of footwear (i.e., a dimension taken along heel-to-toe direction). Accordingly, the upper plate and the lower plate can rotate about the length of the beam and the beam can provide a resistive moment that can oppose and control the movement (i.e., rotation) between the upper plate and the lower plate. In some embodiments, the upper plate, the lower plate, and the beam can be disposed within the forefoot region; however, other configurations are possible. Additionally, in some embodiments, the upper plate, the lower plate, and the beam can be co-molded to form a single unitary body, or they may be configured as separate components that can be coupled to one another, for example, by fasteners or an adhesive. 
     In some embodiments, a sole structure can further include a midsole that is disposed between an upper plate and a lower plate that are pivotably coupled by a beam. More specifically, at least a portion of the midsole is disposed along each of a lateral side of the beam and a medial side of the beam. In some cases, the midsole can at least partially surround the beam along its sides (e.g., the sides of the beam extending between the upper and lower plates), such that a first portion of the midsole is positioned along a lateral side of the beam and so that a second portion of the midsole is positioned along a medial side of the beam. The midsole can be made from, for example, a foam material (e.g., EVA) to provide cushioning for the user. Accordingly, as the upper plate and the lower plate rotate about the beam, at least a portion of the midsole can be compressed between the upper and lower plates. Thus, due to the resilient nature of material of the midsole, the midsole provides an opposing force that resists the movement between the upper and lower plates, thereby controlling the movement by acting as a dampener. In that regard, the specific material properties of the midsole can be chosen to tune the midsole for specific dampening and cushioning characteristics. 
     For example, in some embodiments, the midsole can be a multi-density midsole with two or more portions that can be configured to provide different amounts of cushioning. In particular, a midsole can include a first or lateral midsole portion that is disposed on a lateral side of the flexible member and a second or medial midsole portion that is disposed on a medial side of the flexible member. The lateral midsole member can have a low density to impart the lateral side of the sole structure with enhanced flexibility and cushioning, while the medial midsole member can have a comparatively high density to impart the medial side of the sole structure with increased stability. Correspondingly, such an arrangement can help to reduce pronation. In other embodiments, the midsole can be configured differently, for example, to help reduce pronation in one foot of a user while reducing supination in the other foot. 
     In addition to reducing pronation and supination, by allowing the upper and lower plates to rotate about the beam relative to one another, the sole structure can provide improved traction when moving along a curve, wherein a user’s body naturally leans into a turn, and when moving along uneven or sloped surfaces. In particular, the articulation of the upper and lower plates about the beam can compress a portion of the midsole (e.g., a lateral or medial side), while expanding (e.g., stretching) another portion of the midsole (e.g., the medial or lateral side, respectively), thereby allowing the lower plate to remain approximately parallel with the ground, thereby creating the largest possible contact patch therebetween. 
       FIGS.  1 - 6    depict an exemplary embodiment of an article of footwear  100  including an upper  102  (shown in phantom in  FIGS.  2 - 5   ) and a sole structure  104 , with the sole structure  104  being configured to extend between the upper  102  and the ground. For reference, as illustrated in  FIGS.  1 - 4   , in particular, the article of footwear  100  generally defines a forefoot region  120 , a midfoot region  122 , and a heel region  124 . The forefoot region  120  generally corresponds with portions of the article of footwear  100  that encase portions of the foot that include the toes, the ball of the foot, and joints connecting the metatarsals with the toes or phalanges. The midfoot region  122  is proximate and adjoining the forefoot region  120 , and generally corresponds with portions of the article of footwear  100  that encase the arch of a foot, along with the bridge of a foot. The heel region  124  is proximate and adjoining the midfoot region  122  and generally corresponds with portions of the article of footwear  100  that encase rear portions of the foot, including the heel or calcaneus bone, the ankle, or the Achilles tendon. 
     The article of footwear  100  also defines a lateral side  126 , and a medial side  128 . Further, the article of footwear  100  defines a longitudinal axis  130  that extends from a toe end  132  that is located at a distal end of the forefoot region  120 , to a heel end  134  that is located at a distal end of the heel region  124 , opposite the toe end  132 . The longitudinal axis  130  defines a middle of the article of footwear  100  with the lateral side  126  extending from one side of the longitudinal axis  130  and the medial side  128  extending from the other. Put another way, the lateral side  126  and the medial side  128  adjoin one another along the longitudinal axis  130 . In particular, the lateral side  126  corresponds to an outside portion of the article of footwear  100  and the medial side  128  corresponds to an inside portion of the article of footwear  100 . As such, left and right articles of footwear have opposing lateral  126  and medial  128  sides, such that the medial sides  128  are closest to one another when a user is wearing the article of footwear  100 , while the lateral sides  126  are defined as the sides that are farthest from one another while being worn. 
     The forefoot region  120 , the midfoot region  122 , the heel region  124 , the medial side  128 , and the lateral side  126  are intended to define boundaries or areas of the article of footwear  100 , and collectively span an entire length of the article of footwear  100 , from the toe end  132  to the heel end  134 . It should be appreciated that aspects of the disclosure may refer to portions or elements that are coextensive with one or more of the forefoot region  120 , the midfoot region  122 , the heel region  124 , the medial side  128 , or the lateral side  126 . The forefoot region  120  extends from the toe end  132  to a widest portion  136  of the article of footwear  100  (i.e., a distance between the medial side  128  and the lateral side  126  of the sole structure  104 ). The midfoot region  122  extends from the widest portion  136  to a thinnest portion  138  of the article of footwear  100  (i.e., a distance between the medial side  128  and the lateral side  126  of the sole structure  104 ). The heel region  124  extends from the thinnest portion  138  to the heel end  134  of the article of footwear  100 . 
     The lateral side  126  begins where the toe end  132  intersects the longitudinal axis  130  and bows outward (i.e., away from the longitudinal axis  130 ) along the forefoot region  120  toward the midfoot region  122 . At the widest portion  136 , the lateral side  126  bows inward (i.e., toward the longitudinal axis  130 ) toward the thinnest portion  138 , entering the midfoot region  122 . Upon reaching the thinnest portion  138 , the lateral side  126  bows outward and extends into the heel region  124 . The lateral side  126  then bows back inward toward the heel end  134  and terminates where the heel end  134  intersects with the longitudinal axis  130 . Similarly, the medial side  128  begins where the toe end  132  intersects the longitudinal axis  130  and bows outward (i.e., away from the longitudinal axis  130 ) along the forefoot region  120  toward the midfoot region  122 . At the widest portion  136 , the medial side  128  bows inward (i.e., toward the longitudinal axis  130 ) toward the thinnest portion  138 , entering the midfoot region  122 . Upon reaching the thinnest portion  138 , the medial side  128  bows outward and extends into the heel region  124 . The medial side  128  then bows back inward toward the heel end  134  and terminates where the heel end  134  intersects with the longitudinal axis  130 . 
     It should be understood that numerous modifications may be apparent to those skilled in the art in view of the foregoing description, and individual components thereof, may be incorporated into numerous articles of footwear. Accordingly, aspects of the article of footwear  100  and components thereof, may be described with reference to general areas or portions of the article of footwear  100 , with an understanding the boundaries of the forefoot region  120 , the midfoot region  122 , the heel region  124 , the lateral side  126 , and/or the medial side  128  as described herein may vary between articles of footwear. Furthermore, aspects of the article of footwear  100  and individual components thereof, may also be described with reference to exact areas or portions of the article of footwear  100  and the scope of the appended claims herein may incorporate the limitations associated with these boundaries of the forefoot region  120 , the midfoot region  122 , the heel region  124 , the lateral side  126 , and/or the medial side  128  discussed herein. 
     With continued reference to  FIGS.  1 - 4   , the upper  102  can be configured to at least partially enclose the foot of a user and may be made from one or more materials. As illustrated, the upper  102  is disposed above and coupled to the sole structure  104  (see  FIGS.  2  and  3   ), and can extend along the entirety of each of the lateral side  126  and the medial side  128 , as well as extending over the top of the forefoot region  120  and around the heel region  124 . Accordingly, the upper  102  defines an interior cavity  140  (see  FIGS.  5  and  6   ) into which a foot of a user may be inserted. The upper  102  can be formed from one or more layers. For example, many conventional uppers are formed from multiple elements (e.g., textiles, polymer foam, polymer sheets, leather, and synthetic leather) that are joined through bonding or stitching at a seam. In various embodiments, a knitted component may incorporate various types of yarn that may provide different properties to an upper. In other embodiments, the upper may incorporate multiple layers of different materials, each having different properties, for example, increased breathability or moisture wicking. 
     A number of other features may also be coupled to or included in an upper to provide or enhance certain properties of the upper. For example, an upper can include a tongue (not shown) that may include a tongue lining and/or a foam pad to increase comfort. The tongue may be a separate component that is attached to the upper or it may be integrally formed with one or more layers of the upper. Additionally, an upper can also include a tensioning system  123  that allows a user to adjust the upper to fit a foot of a user. The tensioning system  123  can extend through the midfoot region  122  and/or the forefoot region  120  of the upper  102  and may be attached to the upper  102  by an attachment structure. For example, an upper may include a plurality of holes (e.g., punch holes) and/or eyelets that are configured to slidably receive laces so that the user can secure (e.g., by tightening and tying the laces) the article of footwear to a foot. In other embodiments, a tensioning system may be another laceless fastening system known in the art. 
     Furthermore, an upper can include an insole (not shown) positioned within an interior cavity, which can be in direct contact with a user’s foot while an article of footwear is being worn. Moreover, an upper may also include a liner (not shown) that can increase comfort, for example, by reducing friction between the foot of the user and the upper, and/or providing moisture wicking properties. The liner may line the entirety of interior cavity or only a portion thereof. In other embodiments, a binding (not shown) may surround the opening of the interior cavity to secure the liner to the upper and/or to provide an aesthetic element on the article of footwear. 
     As mentioned above, the sole structure  104  is disposed below the upper  102  and extends between the upper  102  and the ground to support the foot of a user. In general, the sole structure  104  includes a midsole  144  disposed above an outsole  146  that defines a bottom surface  148  of the article of footwear  100 . The midsole  144  is the portion of the sole structure  104  that is disposed between the upper  102  and the outsole  146  and provides cushioning for a user by absorbing the impact that occurs when the user’s foot contacts the ground. Accordingly, the midsole  144  acts as a cushioning member for the article of footwear. In some cases, multiple cushioning members can be provided, which can collectively form the midsole, to impart specific cushioning properties at different regions of the sole structure, in the forefoot region  120 , the midfoot region  122 , the heel region  124 , the lateral side  126 , or the medial side  128 . To provide the desired cushioning characteristics, the thickness of the midsole  144  (e.g., a dimension taken along a direction that is normal to the bottom surface  148 ) can be varied, with thicker regions providing greater cushioning and stability, and thinner regions providing less cushioning and greater flexibility. 
     Additionally, midsole  144 , including any individual cushioning members that collectively form the midsole  144 , can be made of one or more materials to provide the midsole  144  with the desired cushioning characteristics. For example, a cushioning member of a midsole may be individually constructed from a thermoplastic material, such as polyurethane (PU), for example, and/or an ethylene-vinyl acetate (EVA), copolymers thereof, or a similar type of material. In other embodiments, cushioning members of a midsole may be an EVA-Solid-Sponge (“ESS”) material, an EVA foam (e.g., PUMA® ProFoam Lite™, IGNITE Foam), polyurethane, polyether, an olefin block copolymer, a thermoplastic material (e.g., a thermoplastic polyurethane, a thermoplastic elastomer, a thermoplastic polyolefin, etc.), or a supercritical foam. A cushioning member may be a single polymeric material or may be a blend of materials, such as an EVA copolymer, a thermoplastic polyurethane, a polyether block amide (PEBA) copolymer, and/or an olefin block copolymer. One example of a PEBA material is PEBAX®. 
     In embodiments where a cushioning member is formed from a supercritical foaming process, the supercritical foam may comprise micropore foams or particle foams, such as a TPU, EVA, PEBAX®, or mixtures thereof, manufactured using a process that is performed within an autoclave, an injection molding apparatus, or any sufficiently heated/pressurized container that can process the mixing of a supercritical fluid (e.g., CO 2 , N 2 , or mixtures thereof) with a material (e.g., TPU, EVA, polyolefin elastomer, or mixtures thereof) that is preferably molten. During an exemplary process, a solution of supercritical fluid and molten material is pumped into a pressurized container, after which the pressure within the container is released, such that the molecules of the supercritical fluid rapidly convert to gas to form small pockets, e.g., pockets of nitrogen gas, within the material and cause the material to expand into a foam, which may be used as the cushioning member. In further embodiments, a first cushioning member may be formed using alternative methods known in the art, including the use of an expansion press, an injection machine, a pellet expansion process, a cold foaming process, a compression molding technique, die cutting, or any combination thereof. For example, a first cushioning member may be formed using a process that involves an initial foaming step in which supercritical gas is used to foam a material and then compression molded or die cut to a particular shape. 
     The outsole  146  is disposed below the midsole  144  and is configured to contact the ground along the bottom surface  148 . Accordingly, the outsole  146  can be made of a comparatively tough material that can resist wear and provide traction for a user, for example, rubber (natural or synthetic) or rubber-like compounds and composites. Additionally, to further improve traction, some embodiments can include a plurality of ground engaging protrusions  150 , e.g., lugs or spikes. 
     In the illustrated embodiment, the sole structure  104  is configured as an articulable, i.e., flexible, sole structure that can flex perpendicularly to the longitudinal axis  130 . Because the sole structure  104  can flex perpendicularly to the longitudinal axis  130 , the bottom surface  148  of the sole structure  104  can be approximately parallel with the ground, even where the ground is sloped or the article of footwear  100  is tilted, e.g., when running along a curve, so that there is a non-zero angle between the ground and the bottom surface  148 . Put another way, the sole structure  104  can flex so that, when the bottom surface  148  and the ground are not in contact and there is a non-zero angle therebetween, any subsequent contact between the bottom surface  148  and the ground causes the sole structure  104  to flex so that bottom surface  148  is approximately parallel with the ground. In this way, the bottom surface  148  can contact the ground along an entire width, e.g., a dimension extending between the lateral side  126  and the medial side  128 , of the bottom surface  148 . 
     As discussed in greater detail below, to provide for improved flexing capabilities, the sole structure  104  can include multiple discrete sole portions that are spaced apart from one another. For example, in the illustrated embodiment, the sole structure  104  includes a first or forefoot portion  152  that is in a fixed spatial relationship with a second or heel portion  154 . That is, the forefoot portion  152  can extend throughout the forefoot region  120  and partially into the midfoot region  122  and the heel portion  154  can extend throughout the heel region  124  and partially in the midfoot region  122 , such that the forefoot portion  152  and the heel portion  154  are spaced apart by a gap  156  in the midfoot region  122 . Correspondingly, each of the forefoot portion  152  and the heel portion  154  can include respective midsole or outsole portions that are also separated from one another by the gap  156 . Here the gap  156  is positioned in the midfoot region  122 , such that the forefoot portion  152  is disposed predominately in the forefoot region  120  and the heel portion  154  is disposed predominately in the heel region  124 , although both may extend at least partially into the midfoot region  122 . Accordingly, the midsole  144  is discontinuous across at least a portion of the midfoot region  122 . More specifically, the forefoot portion  152  of the sole structure  104 , i.e., each of the first lower plate  164  and the first midsole portion  168 , extend from a first end in the forefoot region  122  to a second end in the midfoot region  122 , and the heel portion  154  of the sole structure  104  extends from a first end in the midfoot region  122  to a second end in the heel region  124 . In other embodiments, the sole structure  104  may be configured differently, for example, as a single unitary body, or to have additional sole portions, for example, another midsole portion (not shown) that is positioned between the forefoot and heel portions. 
     To secure the forefoot portion  152  and the heel portion  154  in this spaced relationship, each of the forefoot portion  152  and the heel portion  154  are fixedly coupled to an upper plate  160 . The upper plate  160  defines an upper surface of the sole structure  104 , which is configured to couple to the upper  102 . Accordingly, each of the forefoot portion  152  and the heel portion  154  extend downwardly, e.g., away from the upper  102 , from the upper plate  160  to make contact with the ground. As illustrated, the upper plate  160  is configured as a curved plate, with a concave side facing upward toward the upper  102  (see  FIGS.  5  and  6   ). In addition, the upper plate  160  extends along the length of the sole structure  104 , between the toe end  132  and the heel end  134 , and throughout a forefoot region  120 , a midfoot region  122 , and a heel region  124 . In other embodiments, the upper plate  160  can be configured differently. For example, the upper plate  160  can be curved differently or be flat, and may only extend along a portion of the sole structure  104 . 
     The forefoot portion  152  is configured to allow the sole structure  104  to flex perpendicularly to the longitudinal axis  130  of the article of footwear  100 . In particular, the forefoot portion  152  includes a first outsole portion configured as a first lower plate  164 . Correspondingly, in some cases, the first lower plate  164  can include one or more ground engaging elements  150 , e.g., cleats, studs, or spikes, that depend from a bottom surface of the first lower plate  164  to engage with the ground, thereby improving traction. In some cases, a separate outsole portion can be coupled to a lower surface of the first lower plate  164 , such as to reduce wear on the first lower plate  164  and increase traction for a user. 
     The first lower plate  164  is spaced from and pivotably coupled with the upper plate  160  by a beam  166 . That is, the first lower plate  164  is spaced below the upper plate  160  to define a gap  165  therebetween and the beam  166  extends across the gap to couple the first lower plate  164  and the upper plate  160  together. Depending on the shape of the plates  160 ,  164 , the gap  165  may be a constant or it may vary. For example, as illustrated in  FIG.  5   , the curvature of the upper plate  160  causes the gap  165  to increase moving outward from the beam  166  to each of the lateral and medial sides  126 ,  128 . Accordingly, due to the gap  165 , the upper plate  160  and the first lower plate  164  can pivot relative to one another via the beam  166 , in either a medial or a lateral direction. For example, and as will be described in greater detail below, the upper plate  160  and the first lower plate  164  can pivot in a lateral direction, i.e., a first direction, to bring their respective lateral sides closer together, while moving their respective medial sides farther apart, or in a medial direction, i.e., a second direction, to bring their respective medial sides closer together, while moving their respective lateral sides farther apart. 
     As shown in  FIG.  1   , the beam can be disposed entirely within the forefoot region  120 . However, it is also possible that the beam  166  may extend from the forefoot region  120  and into either of the midfoot region  122  or the heel region  124 . 
     In general, the sole structure  104 , e.g., the beam  166 , can be configured to allow the upper plate  160  and the first lower plate  164  to rotate relative to one another by a predetermined amount. For example, of the upper plate  160 , the first lower plate  164 , and the beam  166  (see  FIG.  5   ), the upper plate  160  and the first lower plate can be permitted to rotate relative to one another by a first maximum angular rotation in a first rotational direction and to rotate by up to a second maximum angular rotation in a second rotational direction. For example, relative to an unflexed or neutral state in which the upper plate  160  and the lower plate  164  are at a first angle  181  relative to one another (see  FIG.  5   ), the upper plate  160  and the lower plate  164  can rotate away from the neutral state to be at a second angle  183  relative to one another (see  FIG.  6   ), where the angular rotation is the magnitude of the difference between the first angle  181  and the second angle  183 . 
     The first and second maximum angular rotations may be the same angular rotations or different angular rotations, such that the first maximum angular rotation is greater than or less than the second angular rotation. Accordingly, each of the first and second maximum angular rotations may range between about 5 degrees and about 45 degrees, or more specifically, about 45 degrees, about 40 degrees, about 35 degrees, about 30 degrees, about 25 degrees, about 20 degrees, about 15 degrees, about 10 degrees, about 5 degrees, or any ranges therein (e.g., between about 15 degrees and about 30 degrees, between about 10 degrees and about 20 degrees, etc.). 
     The beam  166  is configured as a linear, elongate member with a length  167  (see  FIGS.  1  and  4   ) that is oriented in a heel-to-toe direction, e.g., approximately parallel with the longitudinal axis  130 , and a width  169  (see  FIG.  4   ) that is perpendicular to the length  167  in a lateral-to-medial direction. Further, the beam  166  defines a height  171  between the upper plate  160  and the first lower plate  164 , which is perpendicular to both the length  167  and the width  169 . The beam  166  is an elongate beam in which the length  167  is greater than both the width  169  and the height  171 . In particular, the length  167  can be at least 150%, 200%, 300%, or 400% of one of the width  169  or the height  171 . Additionally, it may be preferrable that, depending on the desired bending or flexing characteristics of the beam, the height  171  is greater than equal to the width, for example, to be at least 100%, 150%, or 300% of the width  169 , as may allow for greater bending of the beam  166 . 
     Further, as shown in  FIG.  4   , the beam  166  is generally aligned with the longitudinal axis  130  to be centered between the lateral and medial sides  126 ,  128  of the sole structure  104 . In some cases, the beam  166  may be biased to be closer to one of the lateral side  126  or the medial side  128 , as it may allow the sole structure  104  to more easily flex to either the lateral side  126  or the medial side  128 . 
     Due to the elongate shape of the beam  166 , the upper plate  160  and the first lower plate  164  can rotate (e.g., pivot or hinge) about the length the beam  166 , e.g., about an axis extending along the length of the beam  166 ), while remaining rigid in a heel-to-toe direction. Depending on the specific characteristics of the beam  166  (e.g., material properties, size, etc.), the beam  166  may flex along its height  171 , e.g., a distance between the upper plate  160  and the first lower plate  164 , or the upper plate  160  or the first lower plate  164  may flex about their respective connections to the beam  166 . 
     The beam  166  can provide a resistive moment that can help to control the movement (i.e., rotation) of the upper plate  160  and the first lower plate  164 . The moment provided by the beam  166  can be tuned in a number of ways. For example, modifying material properties of the beam  166  can either increase (e.g., by using a stiffer material) or decrease (e.g., by using a softer, less stiff material) the resistive moment that can be provided by the beam  166 . Similarly, increasing the width and/or length, and decreasing the height of the beam  166  can increase the resistive moment that can be provided by the beam  166 , while decreasing the width and/or length, and increasing the height can decrease the resistive moment that can be provided by the beam  166 . In other embodiments, other modifications to the beam  166  can also affect the resistance that can be provided by the beam  166 , for example, by including longitudinal grooves along the length of the beam  166 , or projections that extend in a medial-to-lateral direction from the beam  166 . 
     Further, the shape of the beam  166  can also be adjusted to provide a specific bending characteristic, for example, to have an equal resistance to bending in both the lateral and medial directions, or to have different resistance to bending in each of the lateral and medial directions. Further still, the cross sectional shape of the beam  166  can tuned to provide a desired bending characteristic. For example, as is best shown in  FIGS.  5  and  6   , the beam  166  can have a generally rectangular cross-sectional shape. In other embodiments, other cross-sectional shapes can also be used, including, trapezoids, parallelograms, hourglass-like (e.g., with inwardly curving sides), ellipsoids, or other types of cross-sectional shapes. 
     Moreover, the position of the beam  166  can also affect the resistance that can be provided by the beam  166 . For example, in the illustrated embodiment, the beam  166  is disposed approximately in the center of the forefoot region  120 . That is, the beam  166  is disposed between the lateral and medial sides  126 ,  128  so that a central axis running along the length of the beam is aligned with the longitudinal axis  130  of the article of footwear  100 , and so that the beam  166  is approximately equidistant from each of the toe end  132  of the forefoot region  120  and the heel end  134  of the forefoot region  120 . Accordingly, the beam  166  can provide the same effective resistance when the upper plate  160  and the first lower plate  164  rotate to come together on the lateral side  126 , as when the upper plate  160  and the first lower plate  164  rotate to come together on the medial side  126 . However, if the beam  166  were biased so as to be closer to the lateral side  126  than to the medial side  128 , the beam  166  would provide a greater effective resistance when the upper plate  160  and the first lower plate  164  rotate to come together on the lateral side  126 , as compared to when the upper plate  160  and the first lower plate  164  rotate to come together on the medial side  128 . 
     As illustrated in  FIGS.  5  and  6   , the upper plate  160 , the first lower plate  164 , and the beam  166  can be integrally formed with one another. For example, in some cases, the upper plate  160 , the first lower plate  164 , and the beam  166  can be formed as unitary body using an injection or compression molding process. Accordingly, the upper plate  160 , the first lower plate  164 , and the beam  166  can be made from a polymeric material, for example, TPU. In other cases, as may be determined by a specific use of the article of footwear  100 , the one or more of the upper plate  160 , the first lower plate  164 , and the beam  166  can be separate components that are coupled together. For example, the upper plate  160  or the first lower plate  164  can be a carbon fiber or other type of composite plate to provide rigidity and reduce weight, while the beam  166  can be made from a comparatively softer, more flexible material, such as TPU, to promote bending and flexing to allow the upper plate  160  and the first lower plate  164  to pivot relative to one another. In still other embodiments, other combinations are possible, for example, the upper plate  160  can be a separate composite plate, while the beam  166  and the first lower plate  164  can be integrally formed. 
     Additionally, the forefoot portion  152  can include a first midsole portion  168  that can provide further resistance to oppose the movement between the upper plate  160  and the first lower plate  164 , as well as to provide cushioning. As illustrated, the first midsole portion  168  is disposed between the upper plate  160  and the first lower plate  164 , and is configured to at least partially surround the beam  166 . Accordingly, a first part of the first midsole portion  168 , i.e., a lateral portion, can be positioned on a lateral side of the beam  166  to be between the beam  166  and a lateral edge of the sole structure  102 , and a second part of the first midsole portion  168 , i.e., a medial portion, can be positioned on a medial side of the beam  166  to be between the beam  166  and a medial edge of the sole structure  102 . In some cases, the first midsole portion  168  may be in contact with the beam  166 ; however, this may not always be the case. 
     As mentioned above, the first midsole portion  168  provides cushioning, whereby the first midsole portion  168  can compress or expand (i.e., stretch) in response to an impact. Accordingly, the first midsole portion  168  can deform in response to the relative movement of the upper plate  160  and the first lower plate  164  and can provide a corresponding opposing force that resists such movement. 
     For example, with specific reference to  FIG.  3   , when an external force  170  (i.e., pressure) is applied along the lateral side  126  of one or both of the upper plate  160  and the first lower plate  164 , e.g., as may occur when a user takes a step, the upper plate  160  and the first lower plate  164  are brought together along the lateral side  126 . Accordingly, where the first midsole is coupled to both the upper plate  160  and the first lower plate  164 , a first lateral midsole portion  176 , i.e., the lateral side  126  of the first midsole portion  168 , is compressed. At the same time, since the upper plate  160  and the first lower plate  164  can each rotate about the beam  166 , the upper plate  160  and the first lower plate  164  are moved apart from one another along the medial side  128 , thereby stretching a first medial midsole portion  178 , i.e., a medial side  128  of the first midsole portion  168 . The inverse occurs where pressure is applied to the medial side  128 , such that the first lateral midsole portion  176  is stretched and the first medial midsole portion  178  is compressed. As mentioned above, in some cases, the first lateral midsole portion  176  and the first medial midsole portion  178  can be separate midsole portions that collectively form the first midsole portion  168 . Correspondingly, movement of the plates  160 ,  164  relative to one another also changes the magnitude of the gap  165  on each side of the beam  166 . 
     Due to the resilient nature of the material of the first midsole portion  168 , the first midsole portion  168  produces resistive forces at each of the first lateral midsole portion  176  and the first medial midsole portion  178 . More specifically, the compression of the first lateral midsole portion  176  produces a first resistive force  172  that acts in the opposite direction of the external force  170  to push the upper plate  160  and the first lower plate  164  apart on the lateral side  126 . Conversely, the expansion (i.e., stretching) of the first medial midsole portion  178  produces a second resistive force  174  that acts in the same direction as the external force  170  to pull the upper plate  160  and the first lower plate  164  together on the medial side  128 . In this way, the resistive forces  172 ,  174  provided by the first midsole portion  168  create a moment that acts in conjunction with the moment provided by the beam  166  to counteract the external force  170 . 
     In other embodiments, it is possible that the first midsole portion  168 , i.e., either of the first lateral midsole portion  176  or the first medial midsole portion  178 , are only coupled to one of the upper plate  160  or the first lower plate  164 . In such cases, deformation of the first lateral midsole portion  176  or the first medial midsole portion  178  may only occur by compression on the side where the respective portions of the plates  160 ,  164  are moved together, e.g., on the lateral side  126  or the medial side  128 . Conversely, on the opposing side, .i.e., the other of the lateral side  126  or the medial side  128 , where the respective portions of the plates  160 ,  164  are moved apart, the unconnected plate can move independently away from the first midsole portion  168 , so as not to cause stretching of the respective part of the first midsole portion  168 . 
     In some cases, the first midsole portion  168  can be comprised of multiple portions, i.e., sub-portions. For example, the first lateral midsole portion  176  and the first medial midsole portion  178 , which are disposed along the lateral side  126  and the medial side  128  of the beam  166 , respectively, can be configured as separate portions. Each of the first lateral midsole portion  176  and the first medial midsole portion  178  can be made from the same or different materials to allow the flexibility of the sole structure  104  to be tailored for a specific application or purpose. For example, the first lateral midsole portion  176  can be made from a material having a lower density than the first medial midsole portion  178 , or vice versa. This difference in material density can allow the forefoot portion  152  to have differing amounts of flexibility to rotate in each direction. 
     That is, different material properties in the midsole portions  176 ,  178  can result in one of the lateral side  126  or the medial side  128  having a different spring constant or speed of recovery than the other. As a result, one side may be more difficult to deform, i.e., require greater force to cause an equivalent deformation, or may recover to its original shape faster than the other side As one particular example, where the first lateral midsole portion  176  has a lower density than the first medial midsole portion  178 , the lateral side  126  can remain more flexible than the medial side  128 , making it easier, e.g., by requiring less force, for the upper plate  160  and the first lower plate  164  to rotate to come together on the lateral side  126 , as shown in  FIG.  3   , as compared with the medial side  128 . This arrangement can be beneficial in reducing pronation of a foot of a user. In other embodiments, the first lateral midsole portion  176  and the first medial midsole portion  178  can be configured differently, for example, to reduce supination. 
     Additionally, in some cases, materials of the first lateral midsole portion  176  and the first medial midsole portion  178  can be selected to be more flexible in the same direction, e.g., so that a left shoe is more flexible to rotate to a lateral side and so that a corresponding right shoe is more flexible to rotate to a medial side. This may be particularly beneficial in, for example, sports shoes, such as track spikes, which can be configured for use on banked track surfaces with a known angle or range of angles. To that end, the first lateral midsole portion  176  and the first medial midsole portion  178  can be tuned to easily flex within a predetermined angular range, e.g., between about 0 degrees and about 18 degrees from an unflexed state in a first rotational direction, and to be more resilient to flexing outside of that predetermined angular range, e.g., greater than about 18 degrees or less than about 0 degrees from the unflexed state in the first rotational direction, i.e., to rotate in a second, opposite direction. To allow for such variable resistance, the first lateral midsole portion  176  or the first medial midsole portion  178  can be a multiple density cushioning element. 
     As compared with the forefoot portion  152 , the heel portion  154  is not specifically configured to flex perpendicularly to the longitudinal axis  130  of the article of footwear  100 , although it may do so in some cases. That is, the heel portion  154  includes a second outsole portion configured as a second lower plate  180  that is spaced from the upper plate  160 . However, the second lower plate  180  is not pivotably coupled with the upper plate  160  by a beam. Rather, the second lower plate  180  is coupled with the upper plate  160  by a second midsole portion  182  that extends between the second lower plate  180  and the upper plate  160 . In this regard, the heel portion  154  functions in a manner that is similar to a conventional midsole in providing cushioning for a foot of a user. 
     However, in other embodiments, the heel portion  154  can be configured similarly to the forefoot portion  152 , as described above. That is, a heel portion of a sole structure can be configured similarly to the forefoot portion  152  in that it can include a beam and a midsole that is positioned on each of a medial side and a lateral side of the beam, as described above, to provide resistance to bending. Accordingly, a heel portion can also be configured to maintain a corresponding outsole portion in contact with the ground during a heel strike by allowing an upper plate and a lower plate to pivot relative to one another about a beam connecting therebetween. 
     In yet other embodiments, a sole structure for an article of footwear may not include separate and discrete portions, e.g., the forefoot portion  152  and the heel portion  154 . Instead, a sole structure can include an upper plate and an outsole configured as a lower plate, which are joined by a midsole. Accordingly, each of an upper plate, a lower plate, and a midsole can extend throughout a forefoot region, a midfoot region, and a heel region. However, such a sole structure may still include a beam that extends between and connects the upper plate to the lower plate to help guide the sole structure, or portions thereof, to flex perpendicularly to a longitudinal axis of the article of footwear, as described above. 
       FIG.  7    shows a similar sole structure  204  that can be used with the article of footwear  100 . In general, the sole structure  204  is configured similarly to the sole structure  104  in accordance with the description above. However, as shown, the first lateral midsole portion  176  is a first cushioning member made of a first material having a first density and the first medial midsole portion  178  is a second cushioning member made of a second material having a second density. The first and second materials can be different from one another, i.e., have different chemical compositions) or they can be the same material. Likewise, the first and second densities can be different from one another or the same. The first lateral midsole portion  176  and the first medial midsole portion  178  can be connected together, e.g., by an adhesive or comolding, or spaced apart from one another. Additionally, as similarly described above, each of the first lateral midsole portion  176  and the first medial midsole portion  178  are shown being coupled to only the first lower plate  164 . Accordingly, when compressed to the lateral side  126 , the first lateral midsole portion  176  is compressed between the upper plate  160  and the first lower plate  164  on the lateral side  126 , and the upper plate  160  moves away from the first medial midsole portion  178  to define a gap  189  therebetween on the medial side  128 , such that the first medial midsole portion  178  remains in an uncompressed state. 
     Additionally, the upper plate  160  is made of a first material, e.g., a polymeric or composite material, and the first lower plate  164  and beam  166  are integrally formed from a polymeric material. Further, a separate outsole  246  is coupled to a lower surface of the first lower plate  164  to provide a ground contacting surface. 
     Any of the embodiments described herein may be modified to include any of the structures or methodologies disclosed in connection with different embodiments. For example, certain features and combinations of features that are presented with respect to particular embodiments in the discussion above can be utilized in other embodiments and in other combinations, as appropriate. Similarly, materials or construction techniques, other than those disclosed above, may be substituted or added in some embodiments according to known approaches. Further, the present disclosure is not limited to articles of footwear of the type specifically shown. Still further, aspects of the articles of footwear of any of the embodiments disclosed herein may be modified to work with any type of footwear, apparel, or other athletic equipment. 
     As noted previously, it will be appreciated by those skilled in the art that while the disclosure has been described above in connection with particular embodiments and examples, the disclosure is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. 
     INDUSTRIAL APPLICABILITY 
     Numerous modifications to the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.