Patent Publication Number: US-10314367-B2

Title: Sole structure for an article of footwear with extended plate

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims the benefit of priority to U.S. application Ser. No. 14/612,971, filed on Feb. 3, 2015, which claims the benefit of priority to U.S. Provisional Application Ser. No. 61/937,068, filed on Feb. 7, 2014, both of which are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present teachings generally include a sole structure and an article of footwear having the sole structure. 
     BACKGROUND 
     Footwear typically includes a sole configured to be located under a wearer&#39;s foot to space the foot away from the ground or floor surface. Sole structure can be designed to provide a desired level of cushioning. Athletic footwear in particular sometimes utilizes polyurethane foam or other resilient materials in the sole structure to provide cushioning. It is also beneficial for the sole structure for an article of athletic footwear to have a ground contact surface that provides sufficient traction and durability for a particular athletic endeavor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration in side view of an article of footwear with a sole structure that has a plate with an extension portion. 
         FIG. 2  is a schematic illustration in side view of the article of footwear of  FIG. 1  at a first stage of motion. 
         FIG. 3  is a schematic illustration in side view of the article of footwear of  FIG. 1  at a second stage of motion. 
         FIG. 4  is a schematic illustration in side view of the article of footwear of  FIG. 1  at a third stage of motion. 
         FIG. 5  is a schematic illustration in bottom view of the article of footwear of  FIG. 1 . 
         FIG. 6  is a schematic illustration in exploded side view of the plate of  FIG. 1 . 
         FIG. 7  is a schematic illustration in fragmentary plan view of a traction element also shown secured to the plate of the article of footwear in  FIG. 5 . 
         FIG. 8  is a schematic illustration in cross-sectional view of the traction element of  FIG. 7  taken at lines  8 - 8  in  FIG. 7 . 
         FIG. 9  is a schematic illustration in bottom view of an article of footwear having a plate with an alternative extension portion. 
         FIG. 10  is a schematic illustration in bottom view of an article of footwear having a plate with another alternative extension portion. 
         FIG. 11  is a schematic illustration in side view of an article of footwear having a plate with an alternative extension portion. 
         FIG. 12  is a schematic illustration in side view of an article of footwear having a plate with another alternative extension portion. 
         FIG. 13  is a schematic illustration in fragmentary plan view of another alternative extension portion for the plate of  FIG. 1 . 
         FIG. 14  is a schematic illustration in fragmentary plan view of another alternative extension portion for the plate of  FIG. 1 . 
         FIG. 15  is a schematic illustration in fragmentary side perspective view of an article of footwear with a sole structure that has an extension portion. 
         FIG. 16  is a schematic illustration in front perspective view of the article of footwear of  FIG. 15 . 
         FIG. 17  is a schematic illustration in fragmentary bottom view of the article of footwear of  FIG. 15 . 
         FIG. 18  is a schematic illustration in fragmentary cross-sectional view of the article of footwear of  FIG. 15  taken at lines  18 - 18  in  FIG. 17 . 
         FIG. 19  is a schematic illustration in side view of the article of footwear of  FIG. 15 . 
         FIG. 20  is a schematic illustration in side view of the article of footwear of  FIG. 15  at a first stage of motion. 
         FIG. 21  is a schematic illustration in side view of the article of footwear of  FIG. 15  at a second stage of motion. 
         FIG. 22  is a schematic illustration in side view of the article of footwear of  FIG. 15  at a third stage of motion. 
         FIG. 23  is a schematic illustration in side view of an article of footwear with a sole structure that has an extension portion. 
         FIG. 24  is a schematic illustration in side view of an article of footwear with a sole structure that has an extension portion. 
         FIG. 25  is a schematic illustration in side view of an article of footwear with a sole structure that has an extension portion. 
     
    
    
     DETAILED DESCRIPTION 
     An article of footwear has a sole structure with an extension portion that provides a surface area for forward propulsion that maintains contact with the ground during a forward stride, extending the time period for deceleration of loads applied to the sole structure. The article of footwear comprises an upper and a sole structure. The upper has a forefoot region with a foremost extent. The sole structure has a forefoot portion underlying the forefoot region of the upper, and an extension portion extending forward from the forefoot portion. The extension portion extends forward of the foremost extent of the upper from a forward edge of the forefoot portion to a distal end, and a top side of the extension portion is spaced apart from the upper between the forward edge of the forefoot portion and the distal end. The extension portion establishes a propulsion surface beyond the foremost extent of the upper during a forward stride. 
     In an aspect of the disclosure, the forward edge of the forefoot portion has a first width, and the extension portion has a second width greater than the first width. The extension portion thus flares laterally outward relative to the forefoot portion, increasing the surface area of the forefoot portion. 
     In an aspect of the disclosure, the sole structure includes a resilient sole component disposed between the upper and the extension portion. For example, the resilient sole component may be an elastic foam midsole. The resilient sole component extends forward of the upper on the top side of the extension portion. The extension portion may extend forward beyond a forward-most extent of the resilient sole component. The bladder may extend forward beyond a forward-most extent of the resilient sole component. 
     The cushioning component may further comprise an outsole underlying the extension portion. The outsole has a ground contact surface that includes the propulsion surface. Stated differently, the extension portion allows for a greater ground contact surface than a sole structure than terminates at the forefoot portion. 
     In an embodiment of the disclosure, the sole structure includes a bladder having a fluid-filled chamber disposed at least partially in the extension portion. In one or more embodiments, the bladder may also extend in the forefoot portion, at least partially in the midfoot portion, but not in the heel portion. The bladder may include a tether element that spans the fluid-filled chamber from a lower inner surface of the bladder to an upper inner surface of the bladder. 
     The bladder may be disposed at least partially in the forefoot portion of the sole structure and may extend laterally outward of a lateral side of the upper in the forefoot region and medially outward of a medial side of the upper in the forefoot region. In addition to underlying the bladder in the extension portion, the outsole underlies the bladder where it extends laterally outward of the upper. Accordingly, in addition to extending the ground contact surface forward of the forefoot portion, the sole structure has increased ground contact surface in the transverse direction. 
     In an aspect of the disclosure, the sole structure includes an additional plate extending at least partially in the extension portion and disposed adjacent the bladder such that the plate interfaces with the bladder during the forward stride. The additional plate may underlie the bladder and interface with a lower surface of the bladder. The additional plate may overlie the bladder and interfaces with an upper surface of the bladder. There may be two additional plates, a first additional plate that underlies the bladder and interfaces with a lower surface of the bladder, and a second additional plate that overlies the bladder and interfaces with an upper surface of the bladder 
     In an aspect of the disclosure, the extension portion and the forefoot portion have a substantially equal radius of curvature along a length of the sole structure. 
     In an aspect of the disclosure, the sole structure includes a plate and a resilient sole component. The plate has a top side and a bottom side opposite the top side. The top side is nearer to the upper than the bottom side. The resilient sole component is disposed between the upper and the top side of the plate and extends forward of the foremost extent of the upper. The extension portion establishes a ground-contacting propulsion surface beyond the foremost extent of the upper during a forward stride. The plate may be a bladder having a fluid-filled chamber disposed at least partially in the extension portion. 
     In an aspect of the disclosure, the forward edge of the forefoot portion has a first width, and the extension portion has a second width greater than the first width. 
     In an aspect of the disclosure, the sole structure includes an outsole on the bottom side of the plate and underlying the extension portion, and wherein the outsole has a ground contact surface that includes the propulsion surface. 
     In an aspect of the disclosure, the plate includes a bladder having a fluid-filled chamber disposed at least partially in the extension portion. In an aspect of the disclosure, the bladder includes a tether element spanning the fluid-filled chamber from a lower inner surface of the bladder to an upper inner surface of the bladder. 
     In an aspect of the disclosure, the bladder is disposed at least partially in the forefoot portion of the sole structure and extends laterally outward of a lateral side of the upper in the forefoot region and medially outward of a medial side of the upper in the forefoot region. 
     In an aspect of the disclosure, the sole structure has a midfoot portion rearward of the forefoot portion, and a heel portion rearward of the midfoot portion, and the bladder extends only in the midfoot portion, the forefoot portion, and the extension portion. 
     In an aspect of the disclosure, the sole structure includes an additional plate overlying the bladder. In an aspect of the disclosure, the bladder extends forward beyond a forward-most extent of the resilient sole component. 
     In an aspect of the disclosure, the resilient sole component is an elastic foam midsole. In an aspect of the disclosure, the extension portion and the forefoot portion have a substantially equal radius of curvature along a length of the sole structure. 
     In an aspect of the disclosure, an article of footwear comprises an upper having a forefoot region with a foremost extent, and a sole structure having a forefoot portion underlying the forefoot region of the upper, and an extension portion extending forward from the forefoot portion. The extension portion extends forward of the foremost extent of the upper from a forward edge of the forefoot portion to a distal end, and a top side of the extension portion is spaced apart from the upper between the forward edge of the forefoot portion and the distal end. The extension portion establishes a propulsion surface beyond the foremost extent of the upper during a forward stride. 
     In an aspect of the disclosure, the sole structure includes a plate extending at least partially in the extension portion adjacent the bladder and interfacing with an outer surface of the bladder. The plate may overlie the bladder and the outer surface may be an upper surface of the bladder. Alternatively, the bladder may overlie the plate and the outer surface may be a lower surface of the bladder. Still further, the plate may be a first plate that overlies the bladder, the outer surface may be a lower surface of the bladder, and the sole structure may include a second plate extending at least partially in the extension portion adjacent the bladder with the bladder overlying the second plate and the second plate interfacing with a lower surface of the bladder. 
     The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the modes for carrying out the present teachings when taken in connection with the accompanying drawings. 
     “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., are used descriptively relative to the figures, and do not represent limitations on the scope of the invention, as defined by the claims. 
     Referring to the drawings, wherein like reference numbers refer to like components throughout the several views,  FIG. 1  shows an article of footwear  10  that has a sole structure  12 . The article of footwear  10  may include a footwear upper  14  attached to the sole structure  12  and dimensioned according to a specific size chart for a human foot. As shown, the article of footwear  10  is an athletic shoe, such as for running track and field. In other embodiments, the article of footwear  10  could be a dress shoe, a work shoe, a sandal, a slipper, a boot, or any other category of footwear. The article of footwear  10  has a heel region  16 , a midfoot region  18 , and a forefoot region  20 . The heel region  16  generally includes portions of the article of footwear  10  corresponding with rear portions of a human foot of the size of the article of footwear  10 , including the calcaneus bone. The midfoot region  18  generally includes portions of the article of footwear  10  corresponding with an arch area of the human foot of the size of the article of footwear  10 . The forefoot region  20  generally includes portions of the article of footwear  10  corresponding with the toes and the joints connecting the metatarsals with the phalanges of the human foot of the size of article of footwear  10 . 
     The sole structure  12  may also be referred to as a sole assembly, as it may include multiple components. For example, the sole structure  12  may include a resilient sole component  22  attached to the footwear upper  14  and positioned under the footwear upper  14  when the sole structure  12  is resting on a level ground plane G. The sole component  22  may be a material that combines a desired level of resiliency and support, such as, in one example, an ethylene vinyl acetate (EVA) foam. 
     The sole structure  12  includes a plate  24  secured to a first side  26  of the sole component  22  that faces away from the upper  14 . The plate  24  has a heel portion  30 , a midfoot portion  32 , a forefoot portion  34 , and an extension portion  36 . The heel portion  30 , the midfoot portion  32 , and the forefoot portion  34  correspond with the heel region  16 , the midfoot region  18 , and the forefoot region  20 , respectively, of the article of footwear  10 . The heel portion  30  of the plate  24  is defined as the rear third of the sole structure  12 , and is shown in  FIG. 1  as extending from a rear distal end  37  of the sole structure  12  at line A to line B. The midfoot portion  32  of the plate  24  is defined as the middle third of the sole structure  12 , and is shown in  FIG. 1  as extending from line B to line C. The forefoot portion  34  of the plate  24  is defined as the front third of the sole structure  12 , and is shown in  FIG. 1  as extending from line C to line D. For purpose of example only, lines B and C divide the article of footwear  10  lengthwise into equal thirds. 
     The extension portion  36  of the plate  24  extends from the forefoot portion  34  forward to a front distal end  40  of the article of footwear  10 . The extension portion  36  extends further forward than both the sole component  22  and the foremost extent  38  of the upper  14 . In the embodiment of  FIG. 1 , the curvature C 1  of the extension portion  36  is the same as the curvature of the forefoot portion  34 . In other words, the curvature C 1  of the extension portion  36  follows the side profile of the forefoot portion  34 , and the extension portion  36  and the forefoot portion  34  have a substantially equal radius of curvature R. As best shown in  FIG. 5 , the extension portion  36  increases the available surface area of the plate  24  that can be used as a ground contact surface during use of the article of footwear  10 . More specifically, a conventional plate for the sole structure  12  would have a forward distal end  45  at a forward edge  42  of the forefoot portion  34  indicated with a phantom line. The forward distal end  45  of the forefoot portion  34  and a forward distal end  46  of the sole component  22  are both at line D. The extension portion  36  extends forward of the forefoot portion  34  by a first distance D 1  extending from the forward distal end  45  to the distal front end  40 . The first distance D 1  may be from 5 percent to 30 percent of the length L from the rear distal end  37  of the heel portion  30  to the forward distal end  45  of the forefoot portion  34 . Thus, the conventional plate would have a surface area of surface S 1 , rearward of forward edge  42 . The extension portion  36 , however, adds the additional surface area of surface S 2  that extends forward of the forward edge  42  of the forefoot portion to the distal front end  40  of the plate  24 . The plate  24  thus extends from the rear distal end  37  of the sole structure  12  to the front distal end  40  and has a surface area that is the sum of the surface area of surface S 1  and the surface area of surface S 2 . The rear distal end  37  of the sole structure  12  can also be referred to as the rear distal end of the plate  24 . 
     When the article of footwear  10  is worn for certain activities, such as for track and field or other activities involving running, the article of footwear  10  progresses through the stages of motion in order from  FIGS. 1-4 . Alternatively, if the wearer&#39;s running motion is such that the heel portion  30  does not touch the level ground plane G for a period of time, i.e., remains above the ground surface, then the stages of motion may proceed from the stage of  FIG. 2 , through the stages of  FIGS. 3 and 4 , in order. In  FIGS. 3 and 4 , the stages of motion of the article of footwear  10  are such that the extension portion  36  alone establishes a ground contact surface with the level ground plane G. In fact, only a portion of the surface S 2  serves as the ground contact surface during the stages of motion in  FIGS. 3-4 . 
     The plate  24  is specifically configured so that the extension portion  36  has a sufficient stiffness to enable the forefoot portion  34 , the midfoot portion  32 , and the heel portion  30  to be elevated above the level ground plane G while the extension portion  36  lifts from a rear extent of the extension portion  36  (i.e., from the phantom line representing the forward edge  42  at the forward distal end  45  of the forefoot portion) to the front distal end  40  as the article of footwear  10  moves from the stage of motion of  FIG. 3  to the stage of motion of  FIG. 4 . The stiffness of the extension portion  36  is sufficient to support a wearer of the article of footwear  10  in this manner when the article of footwear  10  is subjected to a predetermined range of forces correlated with an expected range of weights of the wearer of the article of footwear  10 . The stiffness of the extension portion  36  allows the article of footwear  10  to effectively pivot forward during the stage of motion in  FIG. 4  about the front distal end  40  rather than pivoting about a forward distal end  45  of the forefoot portion  34 , as would be the case with a conventional plate. 
     To achieve the requisite stiffness to enable the extension portion  36  to function as described while at the same time limiting added weight, the plate  24  may be formed of a composite material. Examples of composite materials include, but are not limited to fiber-reinforced composite materials (including short fiber-reinforced materials and continuous fiber-reinforced materials), fiber-reinforced polymers (including carbon-fiber reinforced plastic and glass-reinforced plastic), carbon nanotube reinforced polymers, as well as any other type of composite materials known in the art. 
     In one embodiment, shown in  FIG. 6 , the plate  24  is made of multiple layers of composite material, such as multiple layers  44 A- 44 M of carbon-reinforced plastic. More specifically, the layers are of different lengths from the rear distal end  37  to the front distal end  40 . Five of the layers  44 A- 44 E extend the entire length of the plate  24 . Four of the layers  44 F- 44 I extend only in the midfoot portion  32 , the forefoot portion  34 , and the extension portion  36 . Two of the layers  44 J- 44 K extend only in the forefoot portion  34  and the extension portion  36 . Two of the layers  44 L- 44 M extend only in the extension portion  36 . Accordingly, in the embodiment shown, the heel portion  30  has five layers, the midfoot portion  32  has nine layers, the forefoot portion  34  has eleven layers, and the extension portion  36  has thirteen layers. In one embodiment, the layers  44 A- 44 M are each of substantially the same thickness and are of the same composite material. The heel portion  30  thus has a first stiffness, the midfoot portion  32  has a second stiffness, the forefoot portion  34  has a third stiffness, and the extension portion  36  has a fourth stiffness. The fourth stiffness is greater in magnitude than the third stiffness, which is greater in magnitude than the second stiffness, which is greater in magnitude than the first stiffness. Each stiffness has a related spring constant and/or other spring characteristic. Thus, the graduated stiffness of the plate  24  in the lengthwise direction, allows the extension portion  36  to have minimal flexing relative to the forefoot portion  34  as the article of footwear  10  rolls forward on the plate  24  from the heel portion  30  to the extension portion  36 . The added length of the extension portion  36 , and the associated added surface area of surface S 2  forward of the forefoot portion  34  relative to a conventional plate effectively enables the plate  24  to provide a propulsion surface at the front of the article of footwear  10  equivalent to that of an article of footwear for a much larger size foot, such that the extension portion  36  acts as a lever. 
     Referring again to  FIG. 5 , the plate  24  has a bottom side  50  that generally faces the level ground plane G and is configured to serve as the ground contact surface. The bottom side  50  is shown in  FIG. 1  opposite a top side  52  of the plate  24 . The sole component  22  is attached to the top side  52  of the plate  24 . The bottom side  50  is also referred to herein as a first side, and the top side  52  is also referred to herein as the second side. Several traction elements  54 A,  54 B,  54 C are secured to the bottom side  50 . A first traction element  54 A is secured to the bottom side  50  at the extension portion  36 . One or more additional traction elements may be secured to the plate  24  at other locations. For example, a second traction element  54 B is secured to the bottom side  50  at the forefoot portion  34 , and extends partially on the midfoot portion  32  of the plate  24 . A third traction element  54 C is secured to the bottom side  50  at the heel portion  30 . The traction elements  54 A- 54 C can be secured to the bottom side  50  by any suitable means such as by the use of adhesives or thermal bonding, depending on the material of the traction elements  54 A- 54 C and of the plate  24 . 
     The plate  24  is generally smooth on the bottom side  50 , and has a relatively low first coefficient of friction. The traction elements  54 A- 54 C are configured with a second coefficient of friction greater than the first coefficient of friction. For example, the plate  24  can be a composite material as discussed herein, and the traction elements  54 A- 54 C can be rubber. Thus, the traction elements  54 A- 54 C provide increased grip of the sole structure  12  to the level ground plane G that prevents the sole structure  12  from slipping relative to the level ground plane G during the phases of motion in  FIGS. 1-4 . The traction elements  54 A- 54 C also minimize lateral rotation of the sole structure  12  relative to the level ground plane G during wear. For example, when the article of footwear  10  is used during running around a curved track, each stride forward by the runner requires some lateral force to be imparted on the sole structure  12 . By increasing traction, the traction elements  54 A- 54 C prevent the lateral force from causing the sole structure  12  to turn clockwise or counterclockwise about a vertical axis through the plate  24  as the lateral force is reacted through one or more of the traction elements  54 A- 54 C.  FIG. 5  shows that the plate  24  has molded mounts  56  configured to retain spikes  58  that serve as additional traction elements. The traction elements  54 A,  54 B,  54 C are shown as discontinuous from one another. In other embodiments, the traction elements  54 A,  54 B and/or  54 C can be interconnected, or fewer or more similar traction elements can be secured to other areas of the bottom side  50 . 
     In the embodiment of  FIGS. 1-8 , the plate  24  serves as an outsole of the article of footwear  10 , as it at least partially establishes the ground contact surface S 1 , S 2 . In other embodiments within the scope of the present teachings, the plate  24  may be positioned elsewhere within the sole structure  12  or within other embodiments of sole structure while still providing the functions described herein with respect to plate  24 . For example, an alternative plate could be positioned within a midsole, such as between layers of a midsole. Still further, an alternative plate could be positioned between an outsole and a midsole. In such embodiments, additional components of the sole structure, such as one or more midsole layers or an outsole, would extend with the plate  24  forward of the foremost extent  38  of the upper  14 . Additionally, in any embodiment, an alternative plate could be multiple components and/or could extend rearward from the extension portion only to the forefoot portion (i.e., so the plate included only an extension portion and a forefoot portion), only to the midfoot portion (i.e., so the plate included only an extension portion, a forefoot portion, and a midfoot portion), or all of the way to the heel portion (i.e., so the plate included an extension portion, a forefoot portion, a midfoot portion, and a heel portion). 
     The traction elements  54 A- 54 C are shown with one example configuration referred to as a lattice pattern. As best shown in  FIG. 7 , the lattice pattern of a portion of traction element  54 A has a first set of substantially parallel elongated strips  60  extending in a first direction, and a second set of substantially parallel elongated strips  62  extending in a second direction substantially perpendicular to the first direction. As used herein, the strips  60  are substantially parallel to one another if adjacent ones of the strips  60  extend lengthwise at less than a 5 percent angle from one another, and the strips  62  are substantially parallel to one another if adjacent ones of the strips  62  extend lengthwise at less than a 5 percent angle from one another. As used herein, the strips  60  are substantially perpendicular to the strips  62  if the strips  60  extend lengthwise at an angle to the strips  62  of between 85 to 95 degrees. The traction element  54 A can be configured so that the strips  60 ,  62  are molded to one another, or the strips  60 ,  62  can be adhered to one another.  FIGS. 7 and 8  show that the traction element  54 A has nubs  64  that extend outward from the strips  60 ,  62 . For example, the nubs  64  extend downward toward the level ground plane G in  FIG. 1 . The nubs  64  can be the same material as the strips  60 ,  62 , or can be a different material, that may be a harder or softer material than the material of the strips  60 ,  62 . The nubs  64  extend from alternating intersections of the strips  60 ,  62  in a repeating pattern in  FIG. 7 . The traction elements  54 A- 54 C could be configured in other patterns or in other arrangements than that shown, and additional or fewer traction elements can be used. 
       FIG. 9  shows an alternative article of footwear  10 A alike in all aspects to the article of footwear  10  shown and described with respect to  FIGS. 1-8 , except having a plate  24 A that has a longer extension portion  36 A than the extension portion  36 . A first traction element  54 D is accordingly longer than first traction element  54 A. The plate  24 A is otherwise alike in all aspects to plate  24 .  FIG. 10  shows an alternative article of footwear  10 B alike in all aspects to the article of footwear  10  shown and described with respect to  FIGS. 1-8 , except having a plate  24 B that has a shorter extension portion  36 B than the extension portion  36  and a first traction element  54 E accordingly longer than first traction element  54 A. The plate  24 B is otherwise alike in all aspects to plate  24 . By way of non-limiting example, a comparison of the extension portions  36 ,  36 A,  36 B of  FIGS. 1, 9, and 10  shows that the extension portion used can extend from 5 percent to 30 percent of the length L of the plate  24 ,  24 A, or  24 B, where the length L extends from the rear distal end  37  to the front distal end  45  of a conventional plate. The length L, indicated in  FIG. 1 , is also the distance from A to D. 
       FIG. 11  shows another alternative embodiment of an article of footwear  10 C that is alike in all aspects to the article of footwear  10  shown and described with respect to  FIGS. 1-8 , except having a plate  24 C that has an extension portion  36 C with a curvature C 2  different than the curvature C 1  of the forefoot portion  34 . The plate  24 D is otherwise alike in all aspects to plate  24 . The curvature C 1  following the profile of the forefoot portion  34  has a radius of curvature R that falls above the second side  52  of the plate  24 C, while the curvature C 2  of the extension portion  36 C has a radius of curvature R 1  that falls below the first side  50  of the plate  24 C. Additionally, the radius of curvature R 1  is smaller than the radius of curvature R. 
       FIG. 12  shows another alternative embodiment of an article of footwear  10 D that is alike in all aspects to the article of footwear  10  shown and described with respect to  FIGS. 1-8 , except having a plate  24 D that has an extension portion  36 D that has a curvature C 3  different than the curvature C 1  of the forefoot portion  34 . The plate  24 D is otherwise alike in all aspects to plate  24 . The curvature C 1  following the profile of the forefoot portion  34  has a radius of curvature R that falls above the second side  52  of the plate  24 D. The curvature C 3  of the extension portion  36 D has a radius of curvature R 2  that also falls above the second side  52  of the plate  24 D, but the radius of curvature R 2  is smaller than the radius of curvature R. 
       FIG. 13  shows a fragmentary plan view of a bottom side of a different extension portion  36 E that can be used with the plate  24  as an alternative to the extension portion  36 . The extension portion  36 E has a plurality of fingers  70  having different shapes.  FIG. 14  shows a fragmentary plan view of a bottom side of another different extension portion  36 F that can be used with the plate  24  as an alternative to the extension portion  36 . The extension portion  36 F flares outward laterally relative to the forefoot portion  34 . Specifically, the extension portion  36 F flares outward both on a lateral side  74  and on a medial side  76 . The flared extension portion  36 F provides enhanced lateral stability. As used herein, a lateral side of a component for an article of footwear, such as lateral side  74  of the extension portion  36 E, is a side that corresponds with the side of the foot of the wearer of the article of footwear  10  that is generally further from the other foot of the wearer (i.e., the side closer to the fifth toe of the wearer). The fifth toe is commonly referred to as the little toe. A medial side of a component for an article of footwear  10 , such as medial side  76  of the extension portion  36 E, is the side that corresponds with an inside area of the foot of the wearer and is generally closer to the other foot of the wearer (i.e., the side closer to the hallux of the foot of the wearer). The hallux is commonly referred to as the big toe. The forefoot portion  34  has a first width W 1  at the forward edge  42 , and the extension portion  36 F has a second width W 2  greater than the first width W 1 . The second width W 2  is shown as the greatest width of the extension portion  36 E, as the extension portion  36 F varies in width, first increasing in width from the forward edge  42  to the greatest width W 2 , then decreasing in width to a front distal end  40 F of the extension portion  36 F, which is also the front distal end of the article of footwear that includes the plate  24 . 
       FIGS. 15-22  show another alternative embodiment of an article of footwear  110  that is alike in many aspects to the article of footwear  10  shown and described with respect to  FIGS. 1-8 . Features and components that are identical to those of the article of footwear  10  are indicated with like reference numbers. The article of footwear  110  has a sole structure  112  and may include a footwear upper  114  attached to the sole structure  112 . In the embodiment shown, the upper  114  is knit in one or more pieces that may be sewn together at seams such as seam  115  shown in  FIG. 18 . 
     The sole structure  112  has a heel portion  130 , a midfoot portion  132 , a forefoot portion  134 , and an extension portion  136  as best shown in  FIG. 19 . The heel portion  130 , the midfoot portion  132 , and the forefoot portion  134  correspond with the heel region  16 , the midfoot region  18 , and the forefoot region  20 , respectively, of the article of footwear  110 . The heel portion  130  of the sole structure  112  is defined as the rear third of the sole structure  112 , and is shown in  FIG. 19  as extending from a rear distal end  137  of the sole structure  112  at line AA to line BB. The midfoot portion  132  of the sole structure  112  is defined as the middle third of the sole structure  112 , and is shown in  FIG. 19  as extending from line BB to line CC. The forefoot portion  134  of the sole structure  112  is defined as the front third of the sole structure  112 , and is shown in  FIG. 19  as extending from line CC to line DD. For purpose of example only, lines BB and CC divide the article of footwear  110  lengthwise into equal thirds. 
     The extension portion  136  of the sole structure  112  includes a resilient sole component  122  secured to the footwear upper  114 , and a bladder  124 . Both the resilient sole component  122  and the bladder  124  extend in the extension portion  136 . In the embodiment of  FIG. 19 , the bladder  124  also extends in the midfoot portion  132 , and the resilient sole component  122  extends in the midfoot portion  132  and the heel portion  130 . For example, in  FIG. 18 , the resilient sole component  122  is an elastic foam midsole. The upper  114  is secured to a top side  125  (i.e., a top surface) of the resilient sole component  122 . The bladder  124  is secured to a bottom side  126  (i.e., a bottom surface) of the resilient sole component  122  that faces away from the upper  114 . Stated differently, the resilient sole component  122  overlies the bladder  124 . A top side  152  (i.e., a top surface) of the bladder  124  is secured to the bottom side  126  of the resilient sole component  122 , such as by thermal bonding or adhesive. 
     As is evident in  FIGS. 15-17 , the top side of the extension portion  136  (which is the top side  125  of the resilient sole component  122 ) is spaced apart from the upper  114  between the forward edge  142  of the forefoot portion  20  and the distal end  140 . Both the top side  125  of the resilient sole component  122  and the top side  152  of the bladder  124  are spaced apart from the upper  114 . 
     The forefoot portion  134  of the sole structure  112  underlies the forefoot region  120  of the upper  114 . The extension portion  136  extends forward from the forefoot portion  134 . More specifically, the extension portion  136  extends forward of the foremost extent  138  of the upper  114  from a forward edge  142  of the forefoot portion  134  to a distal end  140 . The forward edge  142  of the forefoot portion  134  is indicated with a phantom line in  FIG. 17  and represents where a forward edge of a sole structure  112  without an extension portion  136  would lie and corresponds with the foremost extent  138  of the upper  114  in the embodiment shown. The forefoot portion  134  has a forward distal end  145  which falls along the forward edge  142  and is a forward-most extent of the forefoot portion  134 . The forward distal end  145  of the forefoot portion  134  is at line DD. The bladder  124  extends forward of the forward distal end  145  of the forefoot portion  134  by a first distance D 1  to a distal front end  140 . In one or more embodiments, the first distance D 1  may be from about 2 percent to 30 percent of the length L from the rear distal end  137  of the heel portion  130  to the forward distal end  145  of the forefoot portion  134  shown in  FIG. 19 . For example, the first distance D 1  may be 2 percent, 3 percent, 4 percent, 5 percent, 6 percent, 7 percent, 8 percent, 9 percent, 10 percent, 11 percent, 12 percent, thirteen percent, 14 percent, 15 percent 16 percent, 17 percent, 18 percent, 19 percent, 20 percent, 21 percent, 22 percent, 23 percent, 24 percent, 25 percent, 26 percent, 27 percent, 28 percent, 29 percent, or 30 percent. In some embodiments, the first distance D 1  may be from about 5 percent to about 30 percent of the length L. For example, in one embodiment in which the length L is about 300 millimeters, the first distance D 1  may be about 2 millimeters. 
     The resilient sole component  122  also extends forward of the forward distal end  145  of the forefoot portion  134  to a foremost extent  139 , but by a second distance D 2  that is less than the first distance D 1 . Stated differently, the bladder  124  extends forward of the resilient sole component  122 . Thus, a sole structure without an extension portion  136  would have a surface area of surface S 1 , rearward of forward edge  142 . The extension portion  136 , however, adds the additional surface area of surface S 2  that extends forward of the forward edge  142  to the distal front end  140 . The sole structure  112  thus extends from the rear distal end  137  to the front distal end  140  and has a surface area that is the sum of the surface area of surface S 1  and the surface area of surface S 2 . 
     The bottom side  150  of the bladder  124  generally faces the level ground plane G. The bottom side  150  is also referred to herein as a first side, and the top side  152  is also referred to herein as the second side. The sole structure  112  includes an outsole  170  that is secured to the bottom side  150  and includes traction elements  154 . The outsole  170  extends under the heel portion  130 , the midfoot portion  132 , the forefoot portion  134 , and the extension portion  136 , and has a ground-contact surface S 1 , S 2  that includes the surfaces S 1 , S 2 . The outsole  170  is thus configured to serve as the ground contact surface of the sole structure  112 . The extension portion  136  includes the surface S 2 , and thus establishes a propulsion surface beyond the foremost extent  138  of the upper  114  during a forward stride, as is described with respect to  FIGS. 19-22 . The additional surface S 2  extends the amount of time that the outsole  170  is in contact with the ground during a forward stride relative to a sole structure that ends at the forefoot portion (i.e., at forward edge  142 ), thus extending the amount of time for deceleration and cushioning of the sole structure  112  relative to a ground impact. 
     Referring to  FIG. 17 , the outer periphery of the bladder  124  is indicated with dashed lines. The outer periphery of the bladder  124  corresponds with the outer periphery of the outsole  170  in the extension portion  136  and in the forefoot portion  134 . The bladder  124  extends in the midfoot portion  134  as well, but tapers inward of the outer periphery of the outsole  170 , as is shown in  FIG. 17 . The outer periphery of the upper  114  is also indicated with dashed lines in  FIG. 17 .  FIGS. 16 and 17  show that the bladder  124  extends laterally outward of a lateral side  174  of the upper  114  in the forefoot region  120 , and medially outward of a medial side  176  of the upper  114  in the forefoot region  120 . The outsole  170  extends under the bladder  124  from a lateral side to a medial side of the bladder, and thus presents greater ground contact surface than a sole structure that extends only the width of the upper  114  in the forefoot region  120 . The bladder  124  and outsole  170  thereunder thus increase ground-contact area in the lateral and medial directions as well as in a forward direction. 
     Referring to  FIG. 18 , the bladder  124  includes a polymeric housing  173 ,  175  defining and enclosing a fluid-filled chamber  172  disposed at least partially in the extension portion  136  (i.e., that portion forward and/or transversely outward of the forward edge  142  in  FIG. 17 ). The polymeric housing  173 ,  175  includes a top polymeric sheet  173  and a bottom polymeric sheet  175  bonded to one another at a peripheral flange  177  that at least partially creates a seal for the chamber  172 . The polymeric sheets  173 ,  175  can be formed from a variety of materials including various polymers that can resiliently retain a fluid such as air or another gas. Examples of polymer materials for polymeric sheets  173 ,  175  include thermoplastic urethane, polyurethane, polyester, polyester polyurethane, and polyether polyurethane. Moreover, the polymeric sheets  173 ,  175  can each be formed of layers of different materials. In one embodiment, each polymeric sheet  173 ,  175  is formed from thin films having one or more thermoplastic polyurethane layers with one or more barriers layer of a copolymer of ethylene and vinyl alcohol (EVOH) that is impermeable to the pressurized fluid contained therein as disclosed in U.S. Pat. No. 6,082,025, which is incorporated by reference in its entirety. Each polymeric sheet  173 ,  175  may also be formed from a material that includes alternating layers of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer, as disclosed in U.S. Pat. Nos. 5,713,141 and 5,952,065 to Mitchell et al. which are incorporated by reference in their entireties. Alternatively, the layers may include ethylene-vinyl alcohol copolymer, thermoplastic polyurethane, and a regrind material of the ethylene-vinyl alcohol copolymer and thermoplastic polyurethane. The polymeric sheets  173 ,  175  may also each be a flexible microlayer membrane that includes alternating layers of a gas barrier material and an elastomeric material, as disclosed in U.S. Pat. Nos. 6,082,025 and 6,127,026 to Bonk et al. which are incorporated by reference in their entireties. Additional suitable materials for the polymeric sheets  173 ,  175  are disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy which are incorporated by reference in their entireties. Further suitable materials for the polymeric sheets  173 ,  175  include thermoplastic films containing a crystalline material, as disclosed in U.S. Pat. Nos. 4,936,029 and 5,042,176 to Rudy, and polyurethane including a polyester polyol, as disclosed in U.S. Pat. Nos. 6,013,340, 6,203,868, and 6,321,465 to Bonk et al. which are incorporated by reference in their entireties. In selecting materials for the polymeric sheets  173 ,  175 , engineering properties such as tensile strength, stretch properties, fatigue characteristics, dynamic modulus, and loss tangent can be considered. The thicknesses of polymeric sheets  173 ,  175  can be selected to provide these characteristics. In the article of footwear  110 , the polymeric sheets  173 ,  175  are sufficiently transparent that the tether element  180  described herein is visible through the polymeric sheets  173 ,  175  from an exterior of the article of footwear  110 , as indicated by the tensile elements  190  visible in  FIGS. 15-16 and 19-23 . 
     Referring to  FIG. 18 , the bladder  124  includes a tether element  180  spanning the fluid-filled chamber  172  from an inner surface  184  of the top polymeric sheet  173  of the bladder  124  to an inner surface  182  of the bottom polymeric sheet  175  of the bladder  124 . The tether element  180  includes a top plate layer  185  secured to the lower inner surface  184  of the top polymeric sheet  173 , such as with adhesive or thermal bonding. The tether element  180  further includes a bottom plate layer  187  bonded to the upper inner surface  182  of the bottom polymeric sheet  175 . The tether elements  180  include a plurality of tensile elements  190  connected to the top plate layer  185  and to the bottom plate layer  187  and spanning the fluid-filled chamber  172 . Each tensile element  190  shown in the side cross-sectional view of  FIG. 18  represents a row of tensile elements  190  that extend laterally across the fluid-filled chamber  172 , as is evident in  FIGS. 15 and 16 . Tensile elements  190  can provide desired responsiveness, such as disclosed in U.S. Pat. No. 8,479,412 to Peyton et al., which is incorporated by reference herein in its entirety. The tensile elements  190  are placed in tension when the fluid-filled chamber  172  is inflated, and limit the height of the inflated bladder  124  by preventing the polymeric sheets  173 ,  175  from ballooning apart beyond the combined height of the plate layers  185 ,  187  and a tensile element  190 . In a non-limiting example, the bladder  124  may have a maximum height from the top side  152  to the bottom side  150  from about 8 millimeters to about 16 millimeters (mm) (e.g., 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, or 16 mm) when the fluid-filled chamber  172  is inflated to an internal pressure of about 15 pounds per square inch (psi) to about 30 psi (e.g., 15 psi, 16 psi, 17 psi, 18 psi, 19 psi, 20 psi, 21 psi, 22 psi, 23 psi, 24 psi, 25 psi, 26 psi, 27 psi, 28 psi, 29 psi, or 30 psi). Force from an impact of the article of footwear  110  with the ground plane G compresses the fluid gas (e.g., air or nitrogen) in the fluid-filled chamber  172  and is dispersed over the inner surface area of the bladder element  124 . Due to the ability of the fluid-filled chamber  172  to disperse force, the bladder element  124  functions similar to plate  24  of  FIG. 1 , and may be referred to as a plate. 
     Referring again to  FIGS. 15, 16, and 19 , the bladder  124  is disposed only in the extension portion  136 , the forefoot portion  134 , and partially in the midfoot portion  132  (indicated only by hidden lines in  FIG. 17 . As best shown in  FIG. 17 , the bladder  124  tapers in width in the midfoot portion  132 . In  FIGS. 19-22 , a portion of the bladder  124  that extends in to the midfoot portion  132  is thus hidden by the resilient sole component  122  which is disposed laterally outward of that portion. The resilient sole component  122  overlies the bladder  124 . In portions of the midfoot portion  132  and the heel portion  130  in which the bladder  124  does not extend, the resilient sole component  122  extends from the upper  114  to the outsole  170 . The resilient sole component  122  is thus thicker in those areas rearward of the bladder  124 . Alternatively, the resilient sole component  122  could be of uniform thickness from the extension portion  136  to the heel portion  130 , and a separate cushioning component could underlie the resilient sole component  122  rearward of the bladder  124 . 
     Referring to  FIG. 19 , the curvature C 1  of the extension portion  136  is the same as the curvature of the forefoot portion  134 . In other words, the curvature C 1  of the extension portion  136  follows the side profile of the forefoot portion  134 , and the extension portion  136  and the forefoot portion  134  have a substantially equal radius of curvature R, which may provide a seamless feel to a wearer in transitioning from loading on the forefoot portion  134  to loading at least partially on the extension portion  136  during a forward stride. 
       FIGS. 19-22  show the article of footwear progressing through stages of motion during a forward stride.  FIG. 19  shows the article of footwear  110  in a neutral or start position.  FIG. 20  depicts a first stage of motion in which weight is shifted onto the forefoot portion  134  as the heel portion  130  is lifted from the level ground plane G during dorsiflexion. The outsole  170  is shown in contact with the ground plane G at both the extension portion  136  and the forefoot portion  134 . In a second stage of motion shown in  FIG. 21 , a rear section of the forefoot portion  134  is lifted from the ground plane G along with the midfoot portion  132  and the heel portion  130 , while a forward section of the forefoot portion  134  remains in contact with the ground plane G, along with the extension portion  136 . 
     A third stage of motion shown in  FIG. 22  is a “toe-off” position, just prior to the article of footwear  110  being lifted completely out of contact with the ground plane G. The stiffness of the bladder  124  corresponds with its inflation pressure in the fluid chamber  172 . A higher inflation pressure corresponds with a higher bending stiffness, and a lower inflation pressure corresponds with a lower bending stiffness. In the article of footwear  110 , the inflation pressure is low enough to provide some compression in height of the fluid chamber  172  under loading, as indicated by the tension elements depicted in a somewhat slack state. The inflation pressure is also low enough to enable substantial bending along the length of the article of footwear  110  in the forefoot portion  134 , allowing the extension portion  136  to remain in contact with the ground plane G at the third stage. The inflation pressure is great enough to act as a spring, resiliently returning the bladder  124  to its initial height prior to compression under loading. The bladder  124  bends at the forefoot portion  134  more readily than the plate  24  of the article of footwear  10 , and does not pivot about the distal front end  140 . Instead, more of the extension portion  136  stays in contact with the ground plane G over a greater range of flex angles during dorsiflexion in a forward stride both in comparison to a sole structure that terminates at the front edge of the forefoot portion  134  (i.e., has no extension portion  136 ), and in comparison to the extension portion  36  of  FIG. 4 , which is sufficiently stiff to lift from the ground plane G at the stage of motion shown in  FIG. 4 , and pivot about the distal front end  40 . By increasing the surface area of the sole structure  112  to include surface area S 2 , the range of flex angles and duration over which forces are reacted by the sole structure  112  are increased, and cushioning (i.e., deceleration of the ground impact force) is provided for a greater duration. 
       FIG. 23  shows another embodiment of an article of footwear  210  with a sole structure  212 . The article of footwear  210  has many of the same components and functions the same as the article of footwear  110 , except that the sole structure  212  includes an additional plate  225  that is disposed between the resilient sole component  122  and the bladder  124  in the forefoot portion  134  and the extension portion  136 . The additional plate  225  extends at least partially in the extension portion  136  and is disposed adjacent the bladder  124  such that the addition plate  225  interfaces with the bladder  124 , including during a forward stride. The additional plate  225  overlies the bladder element  124  and interfaces with an upper surface of the bladder  124  (i.e., the top side  152 , which establishes and includes an outer surface and also an upper surface of the bladder  124 ). The additional plate  225  is sufficiently stiff to disperse a downward force on the plate  225  (such as due to the weight of the wearer shifting to the forefoot during a forward stride) evening out the distribution of the force over the top side  152  of the bladder  124 . The additional plate  225  may be any of a variety of materials selected to provide a desired bending stiffness. Non-limiting examples of materials suitable for the additional plate  225  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. The additional plate  225  may have a greater compressive stiffness than the resilient sole component  122 , and may have a lower bending stiffness, the same bending stiffness, or a greater bending stiffness than the bladder element  124 . 
       FIG. 24  shows another embodiment of an article of footwear  310  with a sole structure  312 . The article of footwear  310  has many of the same components and functions the same as the article of footwear  210 , except in the sole structure  312 , the additional plate  225  is disposed between the bladder  124  and the outsole  170  in the forefoot portion  134  and the extension portion  136 . The additional plate  225  extends at least partially in the extension portion  136  and is disposed adjacent the bladder  124  such that the addition plate  225  interfaces with the bladder  124 , including during a forward stride. The bladder  124  overlies the additional plate  225  so that the additional plate  225  interfaces with a lower surface of the bladder  124  (i.e., the bottom side  150 , which establishes and includes an outer surface and also a lower surface of the bladder  124 ). The plate  225  may advantageously distribute ground reaction forces over the bottom side  150  of the bladder  124 . Because both the cushioning component  122  and the bladder element  124  come between a foot supported on the sole structure  312  in the upper  114  and the additional plate  225 , and the cushioning component  122  is more compressible than either of the bladder  124  and the plate  225 , the sole structure  312  may have a more cushioned feel to the foot than the sole structure  212 . 
       FIG. 25  shows another embodiment of an article of footwear  410  with a sole structure  412 . The article of footwear  410  has many of the same components and functions the same as the articles of footwear  210  and  310 , except the sole structure  412  includes two additional plates  225 , one disposed between the bladder  124  and the cushioning component  122  (i.e., overlying the bladder  124 ) as in  FIG. 23 , and one disposed between the bladder  124  and the outsole  170  in the forefoot portion  134  and the extension portion  136  (i.e., underlying the bladder  124  as in  FIG. 24 ). 
     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.