Patent Publication Number: US-10758001-B2

Title: Energy return footwear plate

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to U.S. Application No. 62/436,527 filed Dec. 20, 2016, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present teachings generally include a sole plate for an article of footwear. 
     BACKGROUND 
     Footwear typically includes a sole assembly configured to be located under a wearer&#39;s foot to space the foot away from the ground. Sole assemblies in athletic footwear may typically be configured to provide one or more of cushioning, motion control, and resiliency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration in perspective view of a top side of a first embodiment of an energy return sole plate for an article of footwear in a first orientation. 
         FIG. 2  is a schematic illustration in perspective view of a bottom side of the energy return sole plate of  FIG. 1 . 
         FIG. 3  is a schematic illustration in front view of the energy return sole plate of  FIG. 1 . 
         FIG. 4  is a schematic illustration in front view of the energy return sole plate of  FIG. 1  inverted under loading. 
         FIG. 5  is a schematic illustration in side view of an alternative embodiment of an energy return sole plate. 
         FIG. 6  is a schematic illustration in bottom view of another alternative embodiment of an energy return sole plate. 
         FIG. 7  is a schematic illustration in perspective view of the energy return sole plate of  FIG. 6 . 
         FIG. 8  is a schematic illustration in bottom view of another alternative embodiment of an energy return sole plate. 
         FIG. 9  is a schematic illustration in perspective view of the energy return sole plate of  FIG. 8 . 
         FIG. 10  is a schematic illustration in perspective view of an article of footwear including the energy return sole plate of  FIG. 1  in a first orientation. 
         FIG. 11  is a schematic cross-sectional illustration of the article of footwear of  FIG. 10  taken at lines  11 - 11  in  FIG. 10 . 
         FIG. 12  is a schematic cross-sectional illustration of the article of footwear of  FIG. 11  with the sole plate inverted under loading. 
         FIG. 13  is a schematic illustration in perspective view of an article of footwear including an alternative embodiment of an energy return sole plate in a first orientation. 
         FIG. 14  is a schematic cross-sectional illustration of the article of footwear of  FIG. 13  taken at lines  14 - 14  in  FIG. 13 . 
         FIG. 15  is a schematic cross-sectional illustration of the article of footwear of  FIG. 14  with the sole plate inverted under loading. 
         FIG. 16  is a schematic cross-sectional illustration of an article of footwear with an alternative embodiment of an energy return sole plate in a first orientation. 
         FIG. 17  is a schematic illustration in perspective view of an alternative embodiment of an energy return sole plate in a first orientation. 
         FIG. 18  is a schematic illustration in front view of the energy return sole plate of  FIG. 17 . 
         FIG. 19  is a schematic illustration in side view of an article of footwear including the sole plate of  FIG. 17  in a first orientation. 
         FIG. 20  is a schematic illustration in side view of the article of footwear of  FIG. 19  with the energy return sole plate under loading. 
         FIG. 21  is a flow diagram of a method of manufacturing an article of footwear. 
         FIG. 22  is a schematic illustration in perspective view of a sheet of material with an outline of a sole plate shown in phantom indicating where a sole plate will be stamped in from the sheet. 
         FIG. 23  is a schematic illustration in perspective view of a sole plate with a cutting tool cutting an opening in the sole plate. 
         FIG. 24  is a schematic illustration in plan view of an alternative embodiment of an energy return sole plate. 
         FIG. 25  is a schematic illustration in plan view of an alternative embodiment of an energy return sole plate. 
         FIG. 26  is a schematic illustration in plan view of an alternative embodiment of an energy return sole plate. 
     
    
    
     DESCRIPTION 
     A sole plate for an article of footwear comprises a plate body having a first side, a second side, an outer perimeter, at least one opening extending through the plate body from the first side to the second side, and an inner perimeter bounding the at least one opening. The plate body is biased to a first orientation of the inner perimeter relative to the outer perimeter. The plate body inverts at the inner perimeter relative to the outer perimeter under a dynamic load applied to the second side, storing elastic energy. The plate body resiliently returns to the first orientation upon removal of the dynamic load, releasing the stored energy. In addition, the return of the plate body to the first orientation is rapid, occurring while the article of footwear is still in contact with the ground, enabling the energy return to be of benefit to propulsion or cushioning. For example, the at least one opening may be in a forefoot region of the plate body, in which case the released elastic energy contributed to propulsion of the foot during toe-off. Alternatively, the at least one opening may be in the heel region of the plate body, in which case the elastic deformation under dynamic load attenuates impact to protect the calcaneus and the ankle, for example. 
     In an aspect of the disclosure, the first side of the sole plate is concave in the first orientation, and the first side is convex under the dynamic load. In one or more embodiments, the plate body slopes in a first direction from the outer perimeter to the inner perimeter in the first orientation, and the plate body slopes in a second direction opposite from the first direction from the outer perimeter to the inner perimeter under the dynamic load. 
     In an aspect of the disclosure, the at least one opening comprises a plurality of openings. Alternatively, the at least one opening may be a single opening. Under either alternative, the plate body may include a continuous band extending from a medial side of the plate body to a lateral side of the plate body. The outer perimeter is an outer edge of the continuous band, and the inner perimeter is an inner edge of the continuous band. 
     In an aspect of the disclosure, the outer perimeter may extend from a medial side of the plate body to a lateral side of the plate body, and the first side of the plate body has an asymmetrical concave curvature with an apex that is offset toward the lateral side or the medial side. 
     In an aspect of the disclosure, the plate body has a forefoot region, a heel region and a midfoot region disposed between the forefoot region and the heel region. The at least one opening is in the forefoot region, and the heel region of the plate body includes a flange extending from a medial side of the plate body to a lateral side of the plate body. 
     In an aspect of the disclosure, the plate body comprises any one of carbon fiber, spring steel, fiberglass, nylon, a polyether block amide, or a superelastic metal including nitinol. 
     A sole structure for an article of footwear comprises a sole plate having a forefoot region, a lower side, an upper side, an outer perimeter, at least one opening extending through the sole plate from the lower side to the upper side in the forefoot region, and an inner perimeter bounding the at least one opening. The sole plate is biased to a first orientation in which the inner perimeter is raised relative to the outer perimeter. A sole layer overlies the upper side of the sole plate. The sole layer transmits an applied dynamic load to the upper side of the sole plate, resiliently deforming the sole plate to a second orientation in which the inner perimeter is below the outer perimeter under the dynamic load. The sole plate resiliently returns to the first orientation upon removal of the dynamic load. 
     In an aspect of the disclosure, the sole layer has a forefoot region, a heel region, and a midfoot region disposed between the forefoot region of the sole layer and the heel region of the sole layer. The sole plate and the sole layer are fixed to one another in at least one of the heel region of the sole layer and the midfoot region of the sole layer, and the forefoot region of the sole layer is moveable relative to the forefoot region of the sole plate. 
     In an aspect of the disclosure, the sole plate has a heel region, and a midfoot region disposed between the forefoot region of the sole plate and the heel region of the sole plate. The heel region of the sole plate includes a flange extending upward at a rear of the sole plate from a medial side of the sole plate to a lateral side of the sole plate. The flange may be secured to a footwear upper. 
     In an aspect of the disclosure, the sole plate slopes upward from the outer perimeter to the inner perimeter in the first orientation, and slopes downward from the outer perimeter to the inner perimeter in the second orientation when under the dynamic load. 
     In an aspect of the disclosure, the outer perimeter extends around a front of the sole plate from a medial side of the sole plate to a lateral side of the sole plate, and the lower side of the sole plate has an asymmetrical concave curvature with an apex that is transversely offset toward the lateral side or the medial side. 
     In an aspect of the disclosure, the sole plate has a continuous band extending along a front of the sole plate from a medial side of the sole plate to a lateral side of the sole plate in the forefoot region. The outer perimeter is an outer edge of the continuous band. The inner perimeter is an inner edge of the continuous band. 
     In an aspect of the disclosure, the lower side of the sole plate is concave in the forefoot region in a transverse direction of the sole plate in the first orientation. The lower side of the sole plate is convex in the forefoot region in the transverse direction under the dynamic load. 
     In an aspect of the disclosure, the sole plate has a forward extremity that extends forward beyond the sole layer. The sole layer transmits an applied dynamic load to the upper side of the sole plate such that the sole plate bends in the longitudinal direction under the dynamic load, thereby decreasing the curvature of the sole plate and extending the forward extremity of the sole plate further forward relative to the sole layer. 
     In an aspect of the disclosure, the sole structure further comprises an outsole secured to the lower side of the sole plate. The outsole may include a plate with tread elements such as cleats extending from a lower side of the plate, or the outsole may be cleats or one or more discrete outsole elements secured directly to the sole plate. 
     An article of footwear comprises a sole plate having a lower side, an upper side, an outer perimeter, at least one opening extending through the sole plate from the lower side to the upper side, and an inner perimeter bounding the at least one opening. The sole plate is biased to a first orientation in which the inner perimeter is raised relative to the outer perimeter. A sole layer overlies the upper side of the sole plate and has a foot-facing surface. A footwear upper is secured to the sole layer to secure a foot in position above the foot-facing surface. The sole layer transmits a dynamic load applied on the foot-facing surface to the upper side of the sole plate, resiliently deforming the sole plate to a second orientation in which the inner perimeter displaces to below the outer perimeter under the dynamic load. The sole plate resiliently returns to the first orientation upon removal of the dynamic load. The return of the sole plate to the first orientation is rapid, occurring while the article of footwear is still in contact with the ground, enabling the energy return to be of benefit to propulsion or cushioning. 
     In an aspect of the disclosure, the sole layer has a forefoot region, a heel region, and a midfoot region disposed between the forefoot region of the sole layer and the heel region of the sole layer. The at least one opening is in the forefoot region, and the sole plate and the sole layer are fixed to one another in at least one of the heel region of the sole layer and the midfoot region of the sole layer. The forefoot region of the sole layer is moveable relative to the forefoot region of the sole plate. 
     In an aspect of the disclosure, the sole plate has a forefoot region, a heel region, and a midfoot region disposed between the forefoot region of the sole plate and the heel region of the sole plate. The heel region of the sole plate includes a flange extending upward at a rear of the sole plate from a medial side of the sole plate to a lateral side of the sole plate. 
     In an aspect of the disclosure, the sole layer is one of a footbed plate or a foam midsole layer. In an aspect of the disclosure, the sole plate slopes upward from the outer perimeter to the inner perimeter in the first orientation, and slopes downward from the outer perimeter to the inner perimeter in the second orientation when under the dynamic load. 
     In an aspect of the disclosure, the outer perimeter extends around a front of the sole plate from a medial side of the sole plate to a lateral side of the sole plate. The lower side of the sole plate has an asymmetrical concave curvature with an apex that is transversely offset toward the lateral side or the medial side. 
     In an aspect of the disclosure, the sole plate has a continuous band extending along a front of the sole plate from a medial side of the sole plate to a lateral side of the sole plate. The outer perimeter is an outer edge of the continuous band. The inner perimeter is an inner edge of the continuous band. The lower side of the sole plate is concave in a transverse direction of the sole plate in the first orientation. The lower side of the sole plate is convex in the transverse direction under the dynamic load. 
     In an aspect of the disclosure, the sole plate has a forward extremity that extends forward beyond the sole layer in the first orientation. The sole layer transmits the applied dynamic load to the upper side of the sole plate such that the sole plate bends in the longitudinal direction under the dynamic load, thereby decreasing a curvature of the sole plate and extending the forward extremity of the sole plate further forward relative to the sole layer in the second orientation than in the first orientation. 
     In an aspect of the disclosure, the article of footwear further comprises an outsole secured to the lower side of the sole plate. The outsole may include a plate with tread elements such as cleats extending from a lower side of the plate, or the outsole may be cleats or one or more discrete outsole elements secured directly to the sole plate. 
     A method of manufacturing an article of footwear comprises providing a sole plate that includes a plate body, a first side, a second side, an outer perimeter, at least one opening extending through the plate body from the first side to the second side, and an inner perimeter bounding the at least one opening. The plate body is biased to a first orientation of the inner perimeter relative to the outer perimeter. The plate body inverts at the inner perimeter relative to the outer perimeter to a second orientation when under a dynamic load applied to the second side. The plate body resiliently returns to the first orientation upon removal of the dynamic load. The return of the plate body to the first orientation is rapid, occurring while the article of footwear is still in contact with the ground, enabling the energy return to be of benefit to propulsion or cushioning. 
     In an aspect of the disclosure, providing the sole plate comprises molding the sole plate by one of compression molding or injection molding. Molding the sole plate may provide the at least one opening. 
     In an alternative aspect of the disclosure, providing the sole plate comprises stamping the sole plate from a sheet of a material larger than the sole plate. Stamping the sole plate may provide the at least one opening. 
     In an aspect of the disclosure, forming the at least one opening in the sole plate may be by cutting away a portion of the sole plate. In an aspect of the disclosure, the method may comprise securing an outsole to the lower side of the sole plate. 
     For consistency and convenience, directional adjectives are employed throughout this detailed description corresponding to the illustrated embodiments. The term “longitudinal” as used throughout this disclosure refers to a direction extending a length of a component (e.g., an upper or sole structure). In some cases, the longitudinal direction may extend from a forefoot portion to a heel portion of the component. Also, the term “laterally” or “transversely” as used throughout this disclosure refers to a direction extending along a width of a component. In other words, the lateral direction may extend between a medial side and a lateral side of a component. Furthermore, the term “vertical” as used throughout this disclosure refers to a direction generally perpendicular to a lateral and longitudinal direction. For example, in cases where an article is planted flat on a level ground surface, the vertical direction may extend from the ground surface upward. Additionally, the term “inner” refers to a portion of a component disposed closer to an interior of the component, or closer to a foot when the component is assembled in an article of footwear worn on the foot. Likewise, the term “outer” refers to a portion of a component disposed farther from the interior of the component or from the foot. Thus, for example, the inner surface of a component is disposed closer to an interior of the component than the outer surface of the component. This detailed description makes use of these directional adjectives in describing an article and various components of the article, including an upper, a sole structure and/or a sole plate. The term “forward” is used to refer to the general direction from a heel portion toward a forefoot portion, and the term “rearward” is used to refer to the opposite direction, i.e., the direction from the forefoot portion toward the heel portion. The term “anterior” is used to refer to a front or forward component or portion of a component. The term “posterior” is used to refer to a rear or rearward component of portion of a component. 
     The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the best modes for carrying out the present teachings when taken in connection with the accompanying drawings. 
     Referring to the drawings, wherein like reference numbers refer to like components throughout the views,  FIG. 1  shows an embodiment of a sole plate  10  for an article of footwear  12 , such as the article of footwear  12  of  FIG. 10 . The sole plate  10  and other sole plates  210 ,  310 ,  410 ,  510 ,  610 ,  910 ,  1010 , and  1110  described herein are configured to return energy to the foot during a stride. More specifically, the sole plates described herein are biased to a first orientation, and invert to a second orientation when under a dynamic load storing elastic energy, but resiliently return to the first orientation when the dynamic load is removed, releasing the stored elastic energy (which may be referred to herein as spring energy). 
     As used herein, the term “plate”, such as in sole plate, refers to a member of a sole structure that is generally horizontally disposed when assembled in an article of footwear that is resting on the sole structure on a level ground surface, and is generally used to provide structure and form rather than cushioning. A plate need not be a single component but instead can be multiple interconnected components. Portions of a plate can be flat, and portions can be pre-formed with some amount of curvature and variations in thickness when molded or otherwise formed in order to provide a shaped footbed and/or increased thickness for reinforcement in desired areas. 
     With reference to  FIG. 1 , the sole plate  10  has a plate body  14  with a forefoot region  16 , and a midfoot region  18 , and a heel region  20 , and as such is referred to as a full-length sole plate  10 . Alternatively, the sole plate  10  could include only a forefoot region  16  or only a forefoot region  16  and midfoot region  18  and still function as described. In other embodiments within the scope of the present disclosure in which an opening as described in the heel region  20  rather than the forefoot region  16 , a sole plate could have only a heel region  20 , or only a heel region  20  and a midfoot region  18 . 
     The forefoot region  16  generally includes portions of the sole plate  10  corresponding with the toes and the joints connecting the metatarsals with the phalanges of the human foot (interchangeably referred to herein as the “metatarsal-phalangeal joints” or “MPJ” joints). The midfoot region  18  generally includes portions of the sole plate  10  corresponding with an arch area of the human foot, including the navicular joint. The heel region  20  generally includes portions of a sole plate corresponding with rear portions of a human foot, including the calcaneus bone, when the human foot is supported on the sole structure and is a size corresponding with the sole structure. The forefoot region, the midfoot region, and the heel region may also be referred to as a forefoot portion, a midfoot portion, and a heel portion, respectively, and may also be used to refer to corresponding regions of an upper and other components of an article of footwear. The midfoot region  18  is disposed between the forefoot region  16  and a heel region, such as heel region  20 , such that the forefoot region  16  is forward of (i.e., anterior to) the midfoot region  18  and the heel region is rearward of (i.e., posterior to) the midfoot region  18 . 
     The sole plate  10  of  FIG. 1  has a first side  22  shown in  FIG. 2 , also referred to as a lower side  22 . The lower side  22  faces away from a foot when a foot is received in the article of footwear. The sole plate  10  has a second side  24  shown in  FIG. 1 . The second side  24  is also referred to as an upper side  24 , and faces toward the foot and is above the lower side  22  when the sole plate  10  is assembled in an article of footwear worn on a foot. The sole plate  10  has a medial side  23  and a lateral side  25 . The sole plate  10  of  FIGS. 1-4  is a sole plate for a left foot. It should be understood that a sole plate for a right foot is a mirror image of the sole plate  10 . 
     The sole plate  10  has an outer perimeter  26  that extends entirely around the sole plate  10 . For example, the outer perimeter  26  extends around a forward portion  27  of the sole plate  10  from the medial side  23  to the lateral side  25 . At least one opening  28  extends through the plate body  14  from the first side  22  to the second side  24 . Stated differently, the at least one opening  28  passes entirely through the thickness of the sole plate  10 . In the embodiment shown, the opening  28  is in the forefoot region  16 . Alternatively, the at least one opening  28  may be in the heel region  20  of the plate body  14 , in which case the elastic deformation under dynamic load attenuates impact to protect the calcaneus and/or ankle, for example. In the embodiment of  FIGS. 1-5 , the at least one opening  28  is a single opening. An inner perimeter  30  of the plate body  14  bounds the opening  28 . The plate body  14  is formed as a continuous band  29  between the outer perimeter  26  and the inner perimeter  30  at the forefoot portion  16  extending from the medial side  23  of the plate body  14  to the lateral side  25  of the plate body  14  in the forefoot region  16 . The outer perimeter  26  is an outer edge of the continuous band  29 , and the inner perimeter  30  is an inner edge of the continuous band  29 . Stated differently, the sole plate  10  is a continuous closed structure from the inner perimeter  30  to the outer perimeter  26 . The plate body  14  passes completely around the opening  28 , and continuously bounds the opening and defines the inner perimeter  30  at the opening  28 . In other embodiments, the band could be non-continuous. 
     The plate body  14  is specifically configured so that it is biased to a first orientation of the inner perimeter  30  relative to the outer perimeter  26 , with the inner perimeter  30  raised entirely above the outer perimeter  26  in the first orientation. The first orientation is illustrated in  FIGS. 1, 3, 4 and 5 , and may be referred to as a steady state orientation. The plate body  14  is in the first orientation when it is in an unstressed state and when it is bearing load, but the load is a steady state load less than a predetermined maximum steady state load, such as when the sole plate  10  is supporting the weight of a wearer of an article of footwear, but is not undergoing dynamic loading during a foot stride. Under a dynamic load of sufficient magnitude applied to the upper side  24 , the plate body  14  inverts at the inner perimeter  30  relative to the outer perimeter  26  to take on a second orientation, also referred to as a dynamically-loaded or inverted orientation. The second orientation is best shown in  FIG. 4 . In one non-limiting example, the predetermined maximum steady state load may be 1.5 times a population-average body weight for a foot size to which the article of footwear is dimensioned. Alternatively, the maximum steady state load may be 1.5 times the ninety-ninth percentile body weight of the population for the standard foot size for which the article of footwear is dimensioned. Accordingly, when the athlete is loading his/her whole body weight on one foot, the sole plate  10  will not invert. When the athlete is in motion, the dynamic load may increase above the numerical value of the predetermined maximum steady state load, causing the sole plate  10  to invert to the second orientation. 
     With reference to  FIG. 3 , the lower side  22  of the forefoot region  16  is concave in the first orientation, and the upper side  24  is convex in the first orientation. The plate body  14  slopes in a first direction from the outer perimeter  26  to the inner perimeter  30  in the first orientation. The first direction is a direction that has a positive vertical component, as shown in  FIG. 3 , and may be referred to as a direction with a positive slope from the outer perimeter  26  to the inner perimeter  30  relative to a level ground plane G. Ray A in  FIG. 3  extends transversely through the sole plate  10  from the outer perimeter  26  to the inner perimeter  30  and slopes in the first direction. Stated differently, in the first orientation, the inner perimeter  30  is raised relative to the outer perimeter  26 . The distance between the top and bottom of the lateral-medial curvature of the sole plate  10  may be referred to as an offset height OH, and is shown in  FIG. 3 . The offset height OH may be between about 5 millimeters (mm) and 15 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm. Additionally, the size of the opening  28  and the resulting width of the continuous band  29  between the inner perimeter  30  and the outer perimeter  26  affects the ease with which the plate body  14  inverts under the dynamic load (with a wider opening  28  and narrower continuous band  29  promoting inversion relative to a narrower opening  28  and wider continuous band  29 ). The length of the opening  28  and the length relative to width also affect the ease of inversion. For example, a greater length of the area bounded by the inner perimeter  30  and/or a greater length relative to width of the inner perimeter  30  generally increases ease of inversion. The area bounded by the inner perimeter  26  is the area of the opening  28  in embodiments with a single opening (see, e.g.,  FIG. 1 ), and is the area bounding the multiple openings in embodiments having multiple openings as in any of  FIG. 8 or 24-26 . 
     The lower side  22  of the forefoot region  16  is convex in the second direction under the dynamic load, and the upper side  24  is concave, as best shown in  FIG. 4 . The plate body  14  slopes in a second direction opposite from the first direction from the outer perimeter  26  to the inner perimeter  30  in the second orientation when under the dynamic load. The second direction is a direction that has a negative vertical component, as shown in  FIG. 4 , and may be referred to as a direction with a negative slope from the outer perimeter  26  to the inner perimeter  30  relative to a level ground plane G. Ray B in  FIG. 4  extends transversely through the sole plate  10  from the outer perimeter  26  to the inner perimeter  30  and slopes in the second direction. Stated differently, in the second orientation, the outer perimeter  26  is raised relative to the inner perimeter  30 . 
     Inversion of the plate body  14  in this manner causes resilient deformation, which stores elastic energy (also referred to as spring energy). The plate body  14  resiliently returns to the first orientation upon removal of the dynamic load, releasing the stored elastic energy in doing so. The release of the elastic energy urges the plate body  14  back toward the first orientation, moving the inner perimeter  30  relative to the outer perimeter  26  in a direction generally toward the foot supported above the second side  24 , urging the desired direction of movement of the foot during toe-off. 
     In order to be sufficiently biased to the first orientation and to resiliently deform as described, the sole plate  10  has a sufficient thickness between the first and second sides  22 ,  24 , and is of a material that has a sufficient bending stiffness. For example, a carbon fiber plate with a thickness of 0.03-0.05 inches provides desirable energy return under an expected range of dynamic loads produced by a wearer having a population average body weight for a standard footwear size for which the sole plate  10  is designed, and for which the dynamic load may reach, for example, three times the body weight. Non-limiting examples of materials suitable for the sole plate  10  include any one of carbon fiber, spring steel, fiberglass, nylon, a thermoplastic elastomer, such as polyether block amide, or a superelastic metal including nitinol. One example polyether block amide is commercially available under the tradename PEBAX®, from Arkema Inc. in King of Prussia, Pa. USA. 
     With reference to  FIG. 10 , the sole plate  10  is shown assembled in the article of footwear  12 . When so assembled, the sole plate  10  is included in a sole structure  40  of the article of footwear  12 . The sole structure  40  includes a sole layer  42  overlying the upper side  24  of the sole plate  10 . The sole layer  42  has a forefoot region  16 A, a midfoot region  18 A, and a heel region  20 A which correspond with the forefoot region  16 , midfoot region  18 , and heel region  20 , respectively, as described with respect to the sole plate  10 . These regions are illustrated relative to one another in  FIG. 10 . The sole layer  42  may be referred to as a footbed plate, as it is positioned between the foot and the sole plate  10  and may have a curved or contoured geometry that may be similar to the lower contours of the foot. 
     The sole layer  42  may be a compliant, elastic layer, such as a foam layer, to moderate pressure between the foot and the sole plate  10 , or may be a plate formed from a more rigid material such as any of the materials described herein as suitable for the sole plate  10 . An additional layer, such as an insole, may overlie the sole layer  42  and be positioned between the sole layer  42  and the foot, or the sole layer  42  may directly support the foot. A footwear upper  44  is directly or indirectly secured to the sole layer  42  and forms a foot-receiving cavity  45  or void configured to receive a foot, such as through an ankle opening  43 . The upper  44  secures and positions the foot relative to the sole structure  40  and, in the embodiment shown, also includes a forefoot region  16 B, a midfoot region  18 B, and a heel region  20 B. 
     The sole plate  10  and the sole layer  42  are fixed to one another in at least one of the heel region  20  and the midfoot region  18  of the sole layer  42 . In the embodiment of  FIG. 10 , the sole layer  42  is fixed to the sole plate  10  only in the heel region  20 . The heel region  20 A of the sole layer  42  is secured to the heel region  20  of the sole plate  10 . As used herein, the sole plate  10  and the sole layer  42  are fixed to one another in regions where relative movement is not permitted. For example, the sole plate  10  and the sole layer  42  may be secured to one another in the heel region  20 , such as by adhesive, thermally bonding, or ultrasonic welding. 
     The sole plate  10  and the sole layer  42  are connected to one another in the forefoot region  16  of the sole plate  10 , but are done so such that the forefoot region  16 A of the sole layer  42  is moveable relative to the forefoot region  16  of the sole plate  10  over a restricted range of movement. For example, a highly compressible foam or other elastic material  46  can be secured to both a lower side of the sole layer  42  and the upper side  24  of the sole plate  10 . The interface of the sole plate  10  and the sole layer  42  in the forefoot region  16  such as via elastic material  46  allows some amount of restricted relative fore-aft motion between the sole plate  10  and the sole layer  42  in the forefoot region  16 , while limiting or preventing side-to-side motion (also referred to as transverse or lateral motion). The relative fore-aft motion occurs during dorsiflexion and resulting bending in the forefoot region  16 ,  16 A of the sole plate  10  and sole layer  42 , respectively, which are at different positions relative to the same bend axis, and therefore require some relative fore-aft motion as the sole plate  10  moves between the first orientation and the second orientation. 
     The sole structure  40  also includes an outsole  48  secured to and underlying the lower side  22  of the sole plate  10 . The outsole  48  may have tread elements  49 , such as cleats or spikes that at least partially define a ground-engaging surface. In other embodiments, tread elements or spikes could be directly secured to or formed integrally with the sole plate  10  at the lower side  22 . In some embodiments, such as where the article of footwear  12  is a track shoe, the outsole  48  may extend under the sole plate  10  but not under the opening  28 . 
       FIG. 11  shows the sole plate  10  in the first orientation, such as when the sole structure  40  is under steady-state loading. The sole layer  42  overlies the upper side of the sole plate  10 . The concave curvature of the lower side  22  of the sole plate  10  is generally symmetrical between the medial side  23  and the lateral side  25  in the first orientation, with an apex A 1  generally centered between the medial side  23  and the lateral side  25 . The upper side of the plate body  14  of the sole plate  10  is spaced apart from a lower side of the sole layer  42  between the inner perimeter  30  and the outer perimeter  26  in a transverse direction of the plate body  14  in the first orientation as shown in  FIG. 11 . The sole layer  42  transmits an applied dynamic load F of the wearer to the upper side  24  of the sole plate  10 , resiliently deforming the sole plate  10  to the second orientation shown in  FIG. 12  with the inner perimeter  30  inverting relative to the outer perimeter  26  so that the upper side of the plate body  14  abuts the lower side of the sole layer  42  between the inner perimeter  30  and the outer perimeter  26  in the transverse direction of the plate body  14 . The loading may occur during a stride when the wearer&#39;s weight is substantially shifted to the forefoot region  16 , such as during toe-off or when landing on the forefoot region  16  during sprinting or the like. When the dynamic load is removed, the internal bias of the sole plate  10  to its undeformed state causes the sole plate  10  to return to the first orientation of  FIG. 11 . The sole plate  10  thus “pops” upward (generally in the direction opposite to the force F) at the inner perimeter  30  when returning to the first orientation upon removal of the dynamic load, applying energy on the foot in the upward direction, and thus returning the deformation energy to the foot. The sole plate  10  cyclically moves between the first orientation and the second orientation with repetitive foot strides. 
       FIG. 5  is an alternative embodiment of a sole plate  110  that has identical features as sole plate  10  which are indicated with like reference numbers. Sole plate  110  has a forefoot portion  16  and a midfoot portion  18 , but no heel portion. When the sole plate  110  is secured within an article of footwear similar to the position and securement of sole plate  10  in  FIG. 10 , the midfoot portion  18  of the sole plate  110  is secured to the sole layer  42  such as by adhesive, thermally bonding, or ultrasonic welding. The elastic material  46  can be secured to both a lower side  22  of the sole layer  42  and the upper side  24  of the sole plate  110  as described with respect to sole plate  10  in  FIG. 10 . 
       FIGS. 6-7  show an embodiment of a sole plate  210  that is configured identically to sole plate  10  of  FIG. 1  except that the heel region  20  of the plate body  14  includes a flange  50  extending upward relative to the second side  24  at the outer perimeter  26  and around a rear portion  52  of the sole plate body  14  from the medial side  23  of the plate body  14  to the lateral side  25  of the plate body  14 . The flange  50  has an inner surface  54  which in one or more embodiments is secured to an outer surface of the footwear upper  44 . If the footwear upper  44  includes a heel counter, the outer surface of the footwear upper  44  to which the flange  50  may be adhered may be the heel counter. Alternatively, the footwear upper  44  may not have a separate heel counter, and the flange  50  may serve as the heel counter. The plate body  14  at the heel region  20  is also secured to the footwear upper  44  as in the embodiment of sole plate  10  shown in  FIG. 10 . 
       FIGS. 8-9  show an embodiment of a sole plate  310  that is configured identically to sole plate  210  of  FIGS. 6-7  except that a plurality of openings  228  (instead of a single opening  28 ) extend through the plate body  14  of the sole plate  310  from the top side  24  to the bottom side  22  instead of a single opening  28 . The plurality of openings  228  are clustered together and are bounded by a perimeter  330  indicated in phantom. The clustered openings  228  lessen the material of the plate body  14  bounded by the perimeter  330  sufficiently to cause the perimeter  330  to invert relative to the outer perimeter  26  under dynamic loading as described with respect to the inner perimeter of the sole plate  10  of  FIG. 1 . In another embodiment, the opening  28  of  FIG. 1  could be filled with an elastic material that flexes and stretches during movement of the perimeter  330  relative to the outer perimeter  26  as the sole plate  310  moves from the first orientation to the second orientation or from the second orientation to the first orientation. 
       FIGS. 24-26  illustrate embodiments of sole plates  910 ,  1010 , and  1110 , each of which is configured identically to sole plate  210  of  FIGS. 6-7  except that each of these embodiments also has a plurality of openings (instead of a single opening  28 ). FIG.  24  shows a sole plate  910  with a plate body  914  having a plurality of openings  928  that extend through the forefoot region  16  of the plate body  914  from the top side  24  to the bottom side  22 . The plurality of openings  928  are clustered together and are bounded by a perimeter  930  indicated in phantom. The plurality of openings include a variety of differently sized circular openings, with larger circular openings clustered generally in the center of the perimeter  930  and slightly toward the medial side  23 . The sole plate  910  inverts from the first orientation shown in  FIG. 24  (in which the inner perimeter  930  is displaced above the outer perimeter  26 ) to the second orientation as shown and described with respect to sole plates  10 ,  410 , and  510 , and may have an apex A 3  offset toward the medial side  23  as described with respect to sole plate  410  and generally centered under the big toe, where the foot pushes off. The lessening of material is thus focused near the largest opening  928 A and the apex A 3 . When the dynamic load is released, the sole plate  910  returns energy at the apex A 3 , encouraging the foot in the desired push-off direction. 
       FIG. 25  shows a sole plate  1010  with a plate body  1014  having a plurality of openings  1028  that extend through the forefoot region  16  of the plate body  1014  from the top side  24  to the bottom side  22 . The plurality of openings  1028  include a central opening  1028 A and a plurality of peripheral opening  1028 B bounding the central opening  1028 A. The openings  1028  are bounded by a perimeter  1030  indicated in phantom. The plurality of openings  1028  may be slightly toward the medial side  23 . The sole plate  1010  inverts from the first orientation shown in  FIG. 25  (in which the inner perimeter  1030  is displaced above the outer perimeter  26 ) to the second orientation as shown and described with respect to sole plates  10 ,  410 , and  510 , and may have an apex A 3  offset toward the medial side  23  as described with respect to sole plate  410  and generally centered under the big toe, where the foot pushes off. When the dynamic load is released, the sole plate  1010  returns energy at the apex A 3 , encouraging the foot in the desired push-off direction. Alternatively, the apex may be centered at the central opening  1028 A. In either case, the plate body  1014  creates a webbing  1025  between the openings  1028  the spring effect. 
       FIG. 26  shows a sole plate  1110  with a plate body  1114  having a plurality of openings  1128  that extend through the forefoot region  16  of the plate body  1114  from the top side  24  to the bottom side  22 . The plurality of openings  1128  are arranged as slots extending generally rearward from the medial side  23  to the lateral side  25 . The openings  1128  are bounded by a perimeter  1130  indicated in phantom. The sole plate  1110  inverts from the first orientation shown in  FIG. 26  (in which the inner perimeter  1130  is displaced above the outer perimeter  26 ) to the second orientation as shown and described with respect to sole plates  10 ,  410 , and  510 , and may have an apex A 3  offset toward the medial side  23  as described with respect to sole plate  410  and generally centered under the big toe, where the foot pushes off. When the dynamic load is released, the sole plate  1110  returns energy at the apex A 3 , encouraging the foot in the desired push-off direction. 
     In any of the embodiments of sole plates shown and described herein, the sole layer  42  overlying the specific sole plate and/or the outsole  48  disposed adjacent the lower side  22  of the sole plate may be a transparent material so that the specific opening or openings in the plate body are visible there through and provide an aesthetically pleasing quality. 
       FIG. 13  shows an alternative embodiment of an article of footwear  412  that has many of the same components as the article of footwear  12  of  FIG. 10 , which is referenced with identical reference numbers in  FIG. 13 . As evident in  FIG. 14 , the article of footwear  412  includes a sole structure  440  with a plate body  414  that is used in place of plate body  14  in  FIG. 10 . The plate body  414  has the same features and functions as plate body  14 , except that the first side  422  of the plate body  414  has an asymmetrical concave curvature with an apex A 2  that is offset toward the medial side  23 , instead of a symmetrical concave curvature with a centered apex A 1  shown in  FIG. 11 . The second side  424  has an asymmetrical convex curvature centered at apex A 3 . The sole layer  42  is tangent to the second side  424  at the apex A 3 . 
     A downward dynamic load in the vertical direction V applied on the second side  424  of the sole plate  410  has a component F normal to the plate body  414 . For example, the force F may be exerted by an athlete on the sole layer  42  and sole plate  410  during running on a banked track or surface (referred to as “banking”). The force F as shown in  FIG. 14  causes the plate body  414  to invert at the inner perimeter  30  relative to the outer perimeter  26 , as shown in  FIG. 15 . The first side  422  has an asymmetrical convex curvature offset toward the medial side  23  in the second orientation of  FIG. 15 , and the second side  424  has an asymmetrical concave curvature. When the dynamic load F is removed, the plate body  414  resiliently returns to the first orientation. A return force RF of the plate body  414  on the sole layer  42  is normal to the tangent of the plate body  414  and the sole layer  42 . The return force RF thus urges the sole layer  42  (and the foot supported on the sole layer  42  within the upper  44 ) toward the lateral side  25  as is desirable when running on a banked track that slopes upward from the lateral side to the medial side  23  of the article of footwear  412  which is for a left foot. 
       FIG. 16  shows an alternative embodiment of an article of footwear  512  that has many of the same components as the article of footwear  12  of  FIG. 10 , which is referenced with identical reference numbers in  FIG. 13 . As evident in  FIG. 16 , a plate body  514  is used in place of plate body  14  in  FIG. 10 . A sole plate  510  has a plate body  514  that has the same features and functions as plate body  14 , except that the first side  522  of the plate body  514  has an asymmetrical concave curvature with an apex A 4  that is offset toward the lateral side  25 , instead of a symmetrical concave curvature with a centered apex A 1  shown in  FIG. 11 . The second side  524  has an asymmetrical convex curvature centered at apex A 5 . The sole layer  42  is tangent to the second side  524  at the apex A 5 . Similar to plate body  414  of  FIG. 14 , a dynamic load on the plate body  514  will be returned along a line normal to the sole layer  42  at the apex A 5 , urging the sole layer  42  upward and slightly toward the medial side  23 , as is desirable when running on a banked track that slopes upward from the medial side  23  toward the lateral side  25 . 
       FIGS. 17-18  show an alternative embodiment of a sole plate  610  and  FIGS. 19-20  show the sole plate  610  assembled in an article of footwear  612 . The sole plate  610  has many of the same components and features as the sole plate  10  of  FIG. 1 , and these are referenced with identical reference numbers. The sole plate  610  has a plate body  614  with a single opening  628  that extends entirely through the forefoot portion  16  from a first side  622  (lower side) to a second side  624  (upper side). An inner perimeter  630  bounds the at least one opening  628 . The outer perimeter  626  extends from the medial side  23  of the plate body  614  to the lateral side  25  of the plate body  614 . As such, the plate body  614  includes a continuous band  629  extending from the medial side  23  to the lateral side  25 . The outer perimeter  626  is an outer edge of the continuous band  629 , and the inner perimeter  630  is an inner edge of the continuous band  629 . 
     The sole plate  610  is biased to a first orientation in which the inner perimeter  630  is raised relative to an outer perimeter  626  of the sole plate  610 . Stated differently, the sole plate  610  slopes upward from the outer perimeter  626  to the inner perimeter  630  in the first orientation shown in  FIG. 18 , and slopes downward from the outer perimeter  626  to the inner perimeter  630  in the second orientation when under the dynamic load similar to as shown in  FIG. 4  and as indicated in  FIG. 20 . The lower side  622  of the forefoot region  16  of the sole plate  610  is concave in a transverse direction of the sole plate in the first orientation, and the lower side  622  of the forefoot region  16  of the sole plate  610  is convex in the transverse direction under the dynamic load. 
     A sole layer  642  overlies the upper side  624  of the sole plate  610 . The sole layer  642  may be a footbed plate or a foam midsole layer. The sole layer  642  transmits an applied dynamic load F indicated in  FIG. 20  to the upper side  624  of the sole plate, resiliently deforming the sole plate  610  to the second orientation. The sole plate  610  resiliently returns to the first orientation upon removal of the dynamic load. The sole plate  610  and the sole layer  642  are fixed to one another in the heel region  20  such as by adhesive, ultrasonic welding or thermal bonding, and the forefoot region  16 A of the sole layer  642  is moveable relative to the forefoot region  16  of the sole plate  610  as indicated by the relative positions in  FIGS. 19 and 20 . 
     The heel region of the sole plate  610  includes a flange  650  extending upward at a rear of the sole plate  610  from the medial side  23  to the lateral side  25 . The flange  650  extends upward relative to the second side  624  at the outer perimeter  626  and around a rear portion of the sole plate body  614  from the medial side  23  of the plate body  614  to the lateral side  25  of the plate body  614 . The flange  650  has an inner surface  654  which in one or more embodiments is secured to an outer surface of the footwear upper  44 . If the footwear upper  44  includes a heel counter, the outer surface of the footwear upper  44  to which the flange  650  may be adhered may be the heel counter. Alternatively, the footwear upper  44  may not have a separate heel counter, and the flange  650  may serve as the heel counter. 
     The forefoot region  16  of the sole plate  610  is able to move relative to the sole layer  642 . Elastic material  46  such as shown in  FIG. 10  may be used to allow some amount of restricted relative fore-aft motion between the sole plate  610  and the sole layer  642  in the forefoot region  16 , while limiting or preventing side-to-side motion. The plate body  614  at the heel region  20  is also secured to the footwear upper  44  as shown in  FIG. 19 . The heel region  20 A, midfoot region  18 A, and forefoot region  16 A of the sole plate  642  are secured to the footwear upper  44  at the heel region  20 B, the midfoot region  18 B and the forefoot region  16 B, respectively. 
     As best shown in  FIG. 19 , the sole plate  610  has a forward extremity  627  that extends forward beyond a forwardmost extent of the sole layer  642 . When the sole layer  642  transmits the applied dynamic load to the upper side  624  of the sole plate  610  such that the sole plate  610  bends in the longitudinal direction under the dynamic load, the curvature of the sole plate  610  decreases, as is apparent in  FIG. 20  relative to  FIG. 19 , and the forward extremity  627  of the sole plate  610  is thereby made to extend further forward relative to the sole layer  642 . 
     The added length of the sole plate  610  forward of the sole layer  642  in the loaded position of  FIG. 20  adds surface area forward of the sole plate  610  that effectively enables the plate  610  to provide a propulsion surface at the front of the article of footwear  612  equivalent to that of an article of footwear for a much larger size foot, such that the portion of sole plate  610  forward of the sole layer  642  acts as a lever, and the footwear  612  pivots forward about the forwardmost extremity  627  during toe-off rather than pivoting about a forward distal end  631  of the forefoot portion  16 A of the sole layer  642 . 
     A method of manufacturing an article of footwear that includes any of the sole plates  10 ,  110 ,  210 ,  310 ,  410 ,  510 ,  610  disclosed herein is schematically depicted in a flow diagram in  FIG. 21 . The method  700  includes block  702 , providing a sole plate  10 ,  110 ,  210 ,  310 ,  410 ,  510 ,  610  any of which includes a plate body having a forefoot region, a first side, a second side, an outer perimeter, at least one opening extending through the plate body from the first side to the second side in the forefoot region, and an inner perimeter bounding the at least one opening, as described. Any such sole plate has a plate body that is biased to a first orientation of the inner perimeter relative to the outer perimeter, inverts at the inner perimeter relative to the outer perimeter to a second orientation when under a dynamic load applied to the second side, and resiliently returns to the first orientation upon removal of the dynamic load, all as described with respect to the plate bodies  14 ,  414 ,  514 , and  614 . 
     In some embodiments, providing the sole plate with the features and functions described comprises block  704 , molding the sole plate by compression molding or injection molding. For example, the sole plate  10 ,  110 ,  210 ,  310 ,  410 ,  510 ,  610  may be a material that can be molded by one of these processes, such as fiberglass, nylon, or a polyether block amide. 
     As an alternative to molding the sole plate, the method  700  may include block  706 , providing the sole plate by stamping the sole plate from a sheet of a material larger than the sole plate. For example, with reference to  FIG. 22 , a sole plate  10  made of spring steel may be manufactured by stamping the sole plate  10  from a sheet  810  of spring steel material that is larger than the sole plate. The stamping may provide the at least one opening  28  in the sole plate. In other words, the inner perimeter  30  can be stamped either before, after or at the same time that the outer perimeter  26  is stamped, creating the opening  28 . 
     Under the method  700 , the molding itself can provide the at least one opening. Stated differently, a mold assembly can have a mold cavity that defines the opening. Similarly, if the sole plate is stamped in block  706 , the stamping itself can create the opening. Alternatively, the method  700  may include block  708 , forming the at least one opening in the sole plate by cutting away a portion of the sole plate. For example, the sole plate can be molded in block  704  or stamped in block  706  without an opening, and the sole plate can be cut to form the opening.  FIG. 23  shows a sole plate  10  with a cutting tool  815  cutting the opening  28 . The sole plate  10  would be stably supported by clamps or otherwise during the cutting process. If the sole plate  10  is customized for a specific wearer, cutting away a portion of the sole plate  10  to provide the opening  28  would allow a more tailored opening for the wearer than if a mold assembly is used, as the cost of a mold assembly is more suited for use in molding large quantities of sole plates with openings of pre-set dimensions than a custom-sized opening. 
     A sole plate provided with the features described with respect to block  702  may be secured to a sole layer in block  710 , such as to a heel portion or a midfoot portion of an overlying sole layer  42  as described with respect to  FIG. 10 . Additionally, the sole plate can be secured to a footwear upper in block  712  of the method  700 , such as if the sole plate includes the flange  650  of  FIG. 19  which can be secured to footwear upper  44 . An outsole such as outsole  48  can be secured to the lower side  22  of the sole plate  10  in block  714  of the method. The outsole can include a plate that underlies the sole plate  10  but not the opening  28 , or the outsole could be simply tread elements such as cleats  49  secured directly to the lower side  22  of the sole plate  10 . 
     “A,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that at least one of the items is present. A plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, unless otherwise indicated expressly or clearly in view of the context, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, a disclosure of a range is to be understood as specifically disclosing all values and further divided ranges within the range. All references referred to are incorporated herein in their entirety. 
     The terms “comprising,” “including,” and “having” are inclusive and therefore specify the presence of stated features, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, or components. Orders of steps, processes, and operations may be altered when possible, and additional or alternative steps may be employed. As used in this specification, the term “or” includes any one and all combinations of the associated listed items. The term “any of” is understood to include any possible combination of referenced items, including “any one of” the referenced items. The term “any of” is understood to include any possible combination of referenced claims of the appended claims, including “any one of” the referenced claims. 
     Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., may be used descriptively relative to the figures, without representing limitations on the scope of the invention, as defined by the claims. 
     While several modes for carrying out the many aspects of the present teachings have been described in detail, those familiar with the art to which these teachings relate will recognize various alternative aspects for practicing the present teachings that are within the scope of the appended claims. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not as limiting.