Patent Description:
Footwear typically includes a sole structure configured to be located under a wearer's foot to space the foot away from the ground. The sole structure can be designed to provide a desired level of cushioning. Athletic footwear in particular may utilize polyurethane foam and/or other resilient materials in the sole structure to provide cushioning.

Document <CIT> describes a shoe comprising: an insole comprising: a structural sole made of elastic material having a laterally stable and longitudinally stable structure and an outer sole and/or shock-absorbing elements made of comparatively soft, flexible sheathing material, the insole extending out through a soft, flexible edge zone beyond the edge of the structural sole; and an upper which, together with the insole, delimits the interior of the shoe. The insole edge zone, which extends out beyond the structural sole, overlaps the upper and is securely joined to the upper material in the overlap zone.

Document <CIT> describes a midsole assembly for an athletic shoe in which a corrugated sheet is integrally arranged in the midsole thereof. The corrugated sheet provides a proper stiffness of the midsole made of rubber or expandable synthetic resin as well as a proper cushioning property thereof and therefore provides a comfortable feeling when worn, best suited to each athletic activity.

Referring to the drawings, wherein like reference numbers refer to like components throughout the several views, <FIG> shows a first embodiment of a sole plate <NUM> that can be included in a sole structure of an article of footwear, such as but not limited to the sole structure <NUM> of the article of footwear <NUM> shown in <FIG>. As further explained herein, the sole plate <NUM> has multiple transverse waves that absorb dynamic loading by decreasing in elevation from a steady state elevation to a loaded elevation under a dynamic compressive load, and returning to the steady state elevation upon removal of the dynamic compressive load. The resiliency of the sole plate <NUM> contributes to a desirably high percentage energy return of the sole structure <NUM>, i.e., the ratio of the energy released from the sole plate <NUM> in returning to its steady state elevation to the dynamic loading energy absorbed by the elastic deformation of the sole plate <NUM> in moving to its loaded elevation. The energy return may correlate with the height of the sole structure <NUM> after dynamic compressive loading is removed and the rate at which the sole structure <NUM> returns to the unloaded height.

In the embodiment shown, the sole plate <NUM> is a unitary, one-piece component that includes a forefoot region <NUM>, a midfoot region <NUM>, and a heel region <NUM>. In other embodiments, a sole plate with top and bottom surfaces and transverse waves similar to those of sole plate <NUM> may include only two contiguous ones of these regions, such as a midfoot region and at least one of a forefoot region and a heel region.

The sole plate <NUM> has a corrugated top surface <NUM> and a complementary corrugated bottom surface <NUM>. The bottom surface <NUM> is considered "complementary" to the top surface <NUM> because the sole plate <NUM> has an undulating profile at a transverse cross-section taken anywhere through the sole plate <NUM> perpendicular to a longitudinal midline <NUM> of the sole plate <NUM>. For example, at the transverse cross-section shown in <FIG>, the undulating profile P1 includes multiple waves: wave W1, wave W2, wave W3, wave W4, wave W5, wave W6, wave W7, and a partial wave W8. A "wave" as discussed herein begins at a center axis <NUM> of the sole plate <NUM>, rises to a crest above the center axis <NUM>, falls to a trough below the center axis <NUM>, and then rises back to and ends at the center axis <NUM>. Wave W1 begins at a medial edge <NUM> of the sole plate <NUM> (also referred to herein as a medial extremity), and the partial wave W8 ends at a lateral edge <NUM> of the sole plate <NUM> (also referred to herein as a lateral extremity). Although the waves are shown as periodic, rounded waves, each generally following the shape of a sine wave, the waves could be squared or angular.

Each wave W1-W7 has a crest and a trough. For example, wave W1 has a crest C1 and a trough T1. Wave W2 has a crest C2 and a trough T2. Wave W3 has a crest C3 and a trough T3. Wave W4 has a crest C4 and a trough T4. Wave W5 has a crest C5 and a trough T5. Wave W6 has a crest C6 and a trough T6. Wave W7 has a crest C7 and a trough T7. Partial wave W8 has a crest C8. The crests C1-C8 are at the top surface <NUM>, and the troughs T1-T7 are at the bottom surface <NUM>.

Because the waves extend longitudinally, the crests form ridges R1, R2, R3, R4, R5, R6, R7, and R8 at the top surface <NUM> as shown in <FIG>. The ridges R1, R2, R3, R4, R5, R6, R7, and R8 correspond with the crests C1, C2, C3, C4, C5, C6, C7, and C8, respectively. Because the waves extend longitudinally, the troughs forming ridges RA, RB, RC, RD, RE, RF, and RG at the bottom surface <NUM> (as shown in <FIG>) corresponding with troughs T1, T2, T3, T4, T5, T6, and T7, respectively. The ridges R1, R2, R3, R4, R5, R6, R7, and R8 at the top surface <NUM>, and the ridges RA, RB, RC, RD, RE, RF, and RG at the bottom surface <NUM> extend longitudinally and parallel to one another and to the longitudinal midline <NUM> in the forefoot region <NUM>, the midfoot region <NUM>, and the heel region <NUM>. Depending on the shape of the outer perimeter of the sole plate <NUM> at the medial edge <NUM> and the lateral edge <NUM>, individual ones of the ridges may extend in only one or two of the forefoot region, the midfoot region, or the heel region. For example, ridge R1, ridge R2, ridge RA, and ridge RB extend only on the forefoot region <NUM> due to the curvature of the medial edge <NUM>. As a group, however, the ridges extend the entire length of the sole plate <NUM>.

As shown in <FIG>, the sole plate <NUM> can be embedded in a foam midsole <NUM> of the sole structure <NUM>. The top surface <NUM>, bottom surface <NUM>, and the periphery, including both the medial edge <NUM> and the lateral edge <NUM> are encapsulated by the foam midsole <NUM>. In the embodiments shown, the foam midsole <NUM> overlays and is in contact with the entire top surface <NUM>, and underlies and is in contact with the entire bottom surface <NUM>.

The sole plate <NUM> is a resilient material such as a fiber strand-lain composite, a carbon-fiber composite, a thermoplastic elastomer, a glass-reinforced nylon, wood, or steel. The resiliency of the sole plate <NUM> is such that when a dynamic compressive load is applied with at least a component of the force normal to the crests and the troughs (i.e., downward on the crests and with a reaction force upward on the troughs), the transverse waves will decrease in elevation from a steady state elevation to a loaded elevation, and will return to the steady state elevation upon removal of the dynamic compressive load. More specifically, as shown in <FIG> and <FIG>, each of the waves has a steady state elevation. The steady state elevation exists when the sole plate <NUM> is under a steady state load, or is unloaded. A steady state load is a load that remains constant, such as when a wearer of the article of footwear <NUM> is standing relatively still. In <FIG>, the bottom extent of a wearer's foot <NUM> is shown in phantom supported on an insole <NUM> positioned on the midsole <NUM>. An upper <NUM> is secured to the midsole <NUM> and surrounds the foot <NUM>. An outsole <NUM> is secured to a lower extent of the midsole <NUM> such that it is positioned between the midsole <NUM> and the ground G, establishing a ground contact surface of the sole structure <NUM>. Alternatively, the midsole <NUM> could be a unisole, in which case the midsole <NUM> would also at least partially serve as an outsole.

Referring again to <FIG>, each of the multiple waves has an amplitude at its crest, and a depth at its trough. In the sole plate <NUM>, each of the crests C1, C2, C3, C4, C5, C6, C7 and C8 has an equal amplitude A. Additionally, each of the troughs T1, T2, T3, T4, T5, T6, T7 has an equal depth D. In the embodiment shown, the amplitude A is equal to the depth D. "Equal" as used herein in regards to wavelength, elevation, amplitude, and depth refers to a range of magnitudes consistent with production tolerances of the sole plate <NUM>, permitting some variation from absolute equality. For example, equal may refer to any value within <NUM> percent of a given value. The amplitude A of each crest is measured from a center axis <NUM> (i.e., the horizontal axis) of the sole plate <NUM> at the transverse cross section to the crest at the top surface <NUM>. The depth D of each trough is measured from the center axis <NUM> of the sole plate <NUM> at the transverse cross section to the trough at the bottom surface <NUM>.

In other examples, the amplitudes of the waves could vary, the depths of the waves could vary, or both could vary. For example, in one example, the amplitudes of the crests could progressively decrease from the medial edge <NUM> to the lateral edge <NUM>, and the depths of the troughs could progressively decrease from the medial edge <NUM> to the lateral edge <NUM>.

According to the claimed invention, the wavelength of the waves vary, and may do so in correspondence with expected loading. The sole plate <NUM> has waves of a shorter average wave length disposed nearer the medial extremity <NUM> than the waves near the lateral extremity <NUM>. Waves W1, W2, W3, W4, and a portion of wave W5 may extend between the medial extremity <NUM> and the longitudinal midline <NUM> of the sole plate. Waves W6, W7 and the remaining portion of W5 may extend between the longitudinal midline <NUM> and the lateral extremity <NUM> of the sole plate <NUM>. The waves disposed between the longitudinal midline <NUM> and the medial extremity <NUM> have a shorter average wavelength than the waves disposed between the longitudinal midline <NUM> and the lateral extremity <NUM>. Most specifically, as shown in <FIG>, wave W1 has a wavelength L1, wave W2 has a wavelength L2, wave W3 has a wavelength L3, wave W4 has a wavelength L4, wave W5 has a wavelength L5, wave W6 has a wavelength L6, and wave W7 has a wavelength L7. The wavelengths increase in magnitude in order from the medial extremity <NUM> to the lateral extremity <NUM>, with wavelength L2 greater than wavelength L1, wavelength L3 greater than wavelength L2, wavelength L4 greater than wavelength L3, wavelength L5 greater than wavelength L4, wavelength L6 greater than wavelength L5, and wavelength L7 greater than wavelength L6. The wavelength of partial wave W8 is not shown as the sole plate <NUM> does not include the entire length of the wave W8, but a full wavelength of wave W8 would be greater than wavelength L7.

Generally, the compressive stiffness of the sole plate <NUM> under dynamic loading increases as wavelength decreases, as amplitude of the crests increases, and as depth of the troughs increases. Accordingly, the portion of the sole plate <NUM> between the longitudinal midline <NUM> and the medial extremity <NUM> has a greater compressive stiffness than the portion of the sole plate <NUM> between the longitudinal midline <NUM> and the lateral extremity <NUM>. More specifically, the sole plate <NUM> increases in compressive stiffness from the medial extremity <NUM> to the lateral extremity <NUM> at the location of the transverse cross-section of <FIG>. This corresponds with dynamic compressive loading during expected activities, as loads at the medial side of the forefoot region <NUM> are higher than loads at the lateral side of the forefoot region <NUM>.

Compressive stiffness under dynamic loading corresponds with the thickness of the sole plate <NUM> between the top surface <NUM> and the bottom surface <NUM>, with a thicker sole plate <NUM> causing a greater compressive stiffness. The sole plate <NUM> is configured with a constant thickness T over its entire expanse, as is evident in <FIG>. The compressive stiffness of the sole plate <NUM> can thus be tuned by selecting the wave lengths, the amplitudes of the crests, the depths of the troughs, and the thickness of the plate <NUM>, and any variations of these at various regions of the sole plate <NUM>.

As is also apparent in <FIG>, the sole plate <NUM> slopes downward in the midfoot region <NUM> from the heel region <NUM> to the forefoot region <NUM>, creating a flattened S-shape. The forefoot region <NUM> may extend upward at a foremost extent, such that the forefoot region is concave at the foot-facing surface and the sole plate <NUM> has a spoon shape. The midsole <NUM> in which the sole plate <NUM> is embedded may slope in a like manner, to form a footbed shape at its top surface <NUM> shown in <FIG>. The slope of the sole plate <NUM> also helps to lessen the bending stiffness of the sole plate <NUM> at the metatarsal phalangeal joints of the foot <NUM> (i.e., for bending in the longitudinal direction), as the sole plate <NUM> has some pre-curvature under these joints.

<FIG> shows the steady state compressive loading of the sole plate <NUM>, and <FIG> shows the sole plate <NUM> under dynamic compressive loading, represented by vertically downward forces F of the foot <NUM> on the sole structure <NUM> (normal to the crests and troughs) and vertically upward forces F on the sole structure <NUM> (normal to the crests and troughs) due to the reaction force of the ground G. The dynamic compressive forces F may be, for example, loading of the forefoot portion <NUM> during running. The forces F are greater on the waves between the medial edge <NUM> and the longitudinal midline <NUM> than between the lateral edge <NUM> and the longitudinal midline <NUM>. However, the shorter wavelengths of the waves nearest the medial edge <NUM> increase the compressive stiffness of the sole plate <NUM> in this region so that the change in elevation (flattening) of the sole plate <NUM> during dynamic compressive loading is substantially uniform in the different regions despite the different magnitudes of the compressive load, as described.

Although represented at the forefoot region <NUM> in <FIG>, dynamic compressive loading of the sole plate <NUM> and resilient return of the sole plate <NUM> to its elevation under steady state loading also occurs at the heel region <NUM> and the midfoot region <NUM>. As depicted in <FIG>, the sole plate <NUM> flattens somewhat under the compressive loading, in correspondence with the magnitude of the loading. The amplitudes decrease from amplitude A under steady state loading, to amplitude B under compressive loading. The depths of the troughs likewise decrease from depth D under steady state loading to depth E under compressive loading. The elevation of the sole plate <NUM> at each wave, which is the magnitude from the depth of the trough of a wave to the crest of the wave (i.e., the sum of the depth of the trough and the amplitude of the crest), thus decreases under compressive loading from elevation E1 in <FIG> to elevation E2 in <FIG>. The transverse width of the sole plate <NUM> and of the midsole <NUM> may increase under compressive loading as the crests and troughs flatten. Due to the resiliency of the sole plate <NUM>, the amplitude of the crests and the depths of the troughs return to their steady state magnitudes A and D, respectively, when the dynamic compressive load is removed and the waves of the sole plate return to their steady state elevation.

<FIG> show an exemplary not claimed sole plate <NUM> alike in all aspects to sole plate <NUM> except that sole plate <NUM> has transverse waves of equal wavelength from the medial edge <NUM> to the lateral edge <NUM>. The resiliency of the sole plate <NUM> contributes to a desirably high percentage energy return of a sole structure <NUM> shown in <FIG>. The sole plate <NUM> is a unitary, one-piece component that includes a forefoot region <NUM>, a midfoot region <NUM>, and a heel region <NUM>. A sole plate with top and bottom surfaces and transverse waves similar to those of sole plate <NUM> may include only two contiguous ones of these regions, such as a midfoot region and at least one of a forefoot region and a heel region.

The sole plate <NUM> has a corrugated top surface <NUM> and a complementary corrugated bottom surface <NUM>. The bottom surface <NUM> is considered complementary to the top surface <NUM> because the surfaces <NUM>, <NUM> are such that the sole plate <NUM> has an undulating profile P2 at a transverse cross-section taken anywhere through the sole plate <NUM> perpendicular to a longitudinal midline <NUM> of the sole plate <NUM>. For example, at the transverse cross-section shown in <FIG>, the undulating profile P2 includes multiple waves: wave W10, wave W20, wave W30, wave W40, wave W50, wave W60, wave W70, wave W80, wave W90, wave W100, and wave W110. Wave W10 begins at the medial edge <NUM> of the sole plate <NUM>, and wave W110 ends at the lateral edge <NUM> of the sole plate <NUM>. Although the waves are shown as periodic, rounded waves, each generally following the shape of a sine wave, the waves could be squared or angular.

Each wave W10-W110 has a crest and a trough. For example, wave W10 has a crest C10 and a trough T10. Wave W20 has a crest C20 and a trough T20. Wave W30 has a crest C30 and a trough T30. Wave W40 has a crest C40 and a trough T40. Wave W50 has a crest C50 and a trough T50. Wave W60 has a crest C60 and a trough T60. Wave W70 has a crest C70 and a trough T70. Wave W80 has a crest C80 and a trough T80. Wave W90 has a crest C90 and a trough T90. Wave W100 has a crest C100 and a trough T100. Wave W110 has a crest C110 and a trough T110. The crests C10-C110 are at the top surface <NUM>, and the troughs T10-T110 are at the bottom surface <NUM>. Because the waves extend longitudinally, the crests form ridges R10, R20, R30, R40, R50, R60, R70, R80, R90, R100, and R110 at the top surface <NUM> as shown in <FIG>. The ridges R10, R20, R30, R40, R50, R60, R70, R80, R90, R100, and R110 correspond with the crests C10, C20, C30, C40, C50, C60, C70, C80, C90, C100, and C110, respectively. Because the waves extend longitudinally, the troughs forming ridges RA1, RB1, RC1, RD1, RE1, RF1, RG1, RH1, RJ1, RK1, and RL1 at the bottom surface <NUM> (as shown in <FIG>) correspond with troughs T10, T20, T30, T40, T50, T60, T70, T80, T90, T100, and T110, respectively. The ridges R10, R20, R30, R40, R50, R60, R70, R80, R90, R100, and R110 at the top surface <NUM>, and the ridges RA1, RB1, RC1, RD1, RE1, RF1, RG1, RH1, RJ1, RK1, RL1 at the bottom surface <NUM> extend longitudinally and parallel to one another and to the longitudinal midline <NUM> in the forefoot region <NUM>, the midfoot region <NUM>, and the heel region <NUM>. Depending on the shape of the outer perimeter of the sole plate <NUM> at the medial edge <NUM> and the lateral edge <NUM>, individual ones of the ridges may extend in only one or two of the forefoot region, the midfoot region, or the heel region. For example, ridges R10 and RA1 extend only on the forefoot region <NUM> due to the curvature of the medial edge <NUM>. As a group, however, the ridges extend the entire length of the sole plate <NUM>.

As shown in <FIG>, the sole plate <NUM> can be embedded in a foam midsole <NUM> of the sole structure <NUM>. The top surface <NUM>, bottom surface <NUM>, and the periphery, including both the medial edge <NUM> and the lateral edge <NUM> are encapsulated by the foam midsole <NUM>. The foam midsole <NUM> overlays and is in contact with the entire top surface <NUM>, and underlies and is in contact with the entire bottom surface <NUM>.

The sole plate <NUM> is a resilient material such as a fiber strand-lain composite, a carbon-fiber composite, a thermoplastic elastomer, a glass-reinforced nylon, wood, or steel. The resiliency of the sole plate <NUM> is such that when a dynamic compressive load is applied with at least a component of the force normal to the crests and the troughs (i.e., downward on the crests and with a reaction force upward on the troughs), the transverse waves will decrease in elevation from a steady state elevation to a loaded elevation, and will return to the steady state elevation upon removal of the dynamic compressive load. More specifically, as shown in <FIG> and <FIG>, each of the waves has a steady state elevation E1. The steady state elevation exists when the sole plate <NUM> is under a steady state load, or is unloaded. A steady state load is a load that remains constant, such as when a wearer of the article of footwear <NUM> is standing relatively still.

Referring again to <FIG>, each of the multiple waves has an amplitude at its crest, and a depth at its trough. In the sole plate <NUM>, each of the crests C10, C20, C30, C40, C50, C60, C70, C80, C90, C100, and C110 has an equal amplitude A. Additionally, each of the troughs T10, T20, T30, T40, T50, T60, T70, T80, T90, T100, and T110 has an equal depth D. The amplitude A is equal to the depth D. The amplitude A of each crest is measured from a center axis <NUM> (i.e., the horizontal axis) of the sole plate <NUM> at the transverse cross section to the crest at the top surface <NUM>. The depth D of each trough is measured from the center axis <NUM> of the sole plate <NUM> at the transverse cross section to the trough at the bottom surface <NUM>.

In contrast to the claimed sole plate <NUM>, each of the waves W10, W20, W30, W40, W50, W60, W70, W80, W90, W100, and W110 are of an equal wavelength L. The sole plate <NUM> is configured with a constant thickness T over its entire expanse, as is evident in <FIG>. The compressive stiffness of the sole plate <NUM> can thus be tuned by selecting the wave lengths, the amplitudes of the crests, the depths of the troughs, and the thickness of the plate <NUM>, and any variations of these at various regions of the sole plate <NUM>.

As is also apparent in <FIG>, the sole plate <NUM> slopes downward in the midfoot region <NUM> from the heel region <NUM> to the forefoot region <NUM>. The midsole <NUM> in which the sole plate <NUM> is embedded may slope in a like manner, to form a footbed shape at its top surface <NUM> shown in <FIG>. The slope of the sole plate <NUM> also helps to lessen the bending stiffness of the sole plate <NUM> at the metatarsal phalangeal joints of the foot <NUM> (i.e., for bending in the longitudinal direction), as the sole plate <NUM> has some pre-curvature under these joints.

<FIG> shows the steady state compressive loading of the sole plate <NUM>, and <FIG> shows the sole plate <NUM> under dynamic compressive loading, represented by vertically downward forces F of the foot <NUM> on the sole structure <NUM> (normal to the crests and troughs) and vertically upward forces F on the sole structure <NUM> (normal to the crests and troughs) due to the reaction force of the ground G. The forces F are greater on the waves between the medial edge <NUM> and the longitudinal midline <NUM> than between the lateral edge <NUM> and the longitudinal midline <NUM>. The dynamic compressive load indicated by arrows F may be, for example, loading of the forefoot portion <NUM> during running. Although represented at the forefoot region <NUM> in <FIG>, dynamic compressive loading of the sole plate <NUM> and resilient return to the steady state loading also occurs at the heel region <NUM> and the midfoot region <NUM>.

As depicted in <FIG>, the sole plate <NUM> flattens somewhat under the compressive loading, in correspondence with the magnitude of the loading. Because the wavelength L of each of the waves W10-W110 is constant in the sole plate <NUM>, and does not vary in correspondence with the dynamic loading as does the sole plate <NUM>, the amplitudes of those waves that bear greater dynamic compressive loads decrease more than those that bear lesser loads. The amplitude of the waves thus decrease from amplitude A under steady state loading shown in <FIG>, to various smaller amplitudes under dynamic compressive loading shown in <FIG>. The depths of the troughs likewise decrease from depth D under steady state loading to various smaller depths under dynamic compressive loading. The elevation of the sole plate <NUM> thus decreases under compressive loading from elevation E1 in <FIG> to various smaller elevations in <FIG>. The transverse width of the sole plate <NUM> and of the midsole <NUM> may increase under compressive loading as the crests and troughs flatten. Due to the resiliency of the sole plate <NUM>, the amplitude of the crests and the depths of the troughs return to their steady state magnitudes A and D, respectively, when the dynamic compressive load is removed. The elevation of the sole plate <NUM> at each wave thus also returns to its steady state elevation.

Although sole plates <NUM> and <NUM> are full-length sole plates as they each have a forefoot region <NUM>, a midfoot region <NUM>, and a heel region <NUM>, other sole plates within the scope of the present teachings may have only two contiguous ones of these regions. For example, sole plate <NUM> in <FIG> has only a forefoot region <NUM> and a midfoot region <NUM>, and sole plate <NUM> in <FIG> has only a midfoot region <NUM> and a heel region <NUM>. Sole plates <NUM> and <NUM> have transverse waves arranged as in sole plate <NUM>, with wavelengths that increase from a medial edge <NUM> to a lateral edge <NUM>. Sole plate <NUM> of <FIG>, not according to the claimed invention, has only a forefoot region <NUM> and a midfoot region <NUM>, and sole plate <NUM> in <FIG>, not according to the claimed invention, has only a midfoot region <NUM> and a heel region <NUM>. The not-claimed sole plates <NUM> and <NUM> have transverse waves arranged as in sole plate <NUM>, with wavelengths that are constant from a medial edge <NUM> to a lateral edge <NUM>.

Assembled, ready to wear footwear articles (e.g., shoes, sandals, boots, etc.), as well as discrete components of footwear articles (such as a midsole, an outsole, an upper component, etc.) prior to final assembly into ready to wear footwear articles, are considered and alternatively referred to herein in either the singular or plural as "article(s) of footwear" or "footwear".

As used in the description and the accompanying claims, unless stated otherwise, a value is considered to be "approximately" equal to a stated value if it is neither more than <NUM> percent greater than nor more than <NUM> percent less than the stated value.

The term "longitudinal" refers to a direction extending a length of a component. For example, a longitudinal direction of an article of footwear extends between a forefoot region and a heel region of the article of footwear. The term "forward" or "anterior" is used to refer to the general direction from a heel region toward a forefoot region, and the term "rearward" or "posterior" is used to refer to the opposite direction, i.e., the direction from the forefoot region toward the heel region. In some cases, a component may be identified with a longitudinal axis as well as a forward and rearward longitudinal direction along that axis. The longitudinal direction or axis may also be referred to as an anterior-posterior direction or axis.

The term "transverse" refers to a direction extending a width of a component. For example, a transverse direction of an article of footwear extends between a lateral side and a medial side of the article of footwear. The transverse direction or axis may also be referred to as a lateral direction or axis or a mediolateral direction or axis.

The term "vertical" refers to a direction generally perpendicular to both the lateral and longitudinal directions. For example, in cases where a sole structure is planted flat on a ground surface, the vertical direction may extend from the ground surface upward. It will be understood that each of these directional adjectives may be applied to individual components of a sole structure. The term "upward" or "upwards" refers to the vertical direction pointing towards a top of the component, which may include an instep, a fastening region and/or a throat of an upper. The term "downward" or "downwards" refers to the vertical direction pointing opposite the upwards direction, toward the bottom of a component and may generally point towards the bottom of a sole structure of an article of footwear.

Claim 1:
A sole structure (<NUM>) for an article of footwear (<NUM>) comprising:
a sole plate (<NUM>, <NUM>, <NUM>) including a medial extremity (<NUM>), a lateral extremity (<NUM>), a midfoot region (<NUM>) and at least one of a forefoot region (<NUM>) and a heel region (<NUM>);
wherein the sole plate (<NUM>, <NUM>, <NUM>) has an undulating profile (P1) at a transverse cross-section of the sole plate (<NUM>, <NUM>, <NUM>),
the undulating profile (P1) including multiple waves (W1, W2, W3, W4, W5, W6, W7, W8) each having a crest (C1, C2, C3, C4, C5, C6, C7, C8) and a trough (T1, T2, T3, T4, T5, T6, T7, T8), and
the sole plate has ridges (R1, R2, R3, R4, R5, R6, R7, R8) corresponding with the crest and the trough of each wave and extending longitudinally throughout the midfoot region (<NUM>) and the at least one of a forefoot region (<NUM>) and a heel region (<NUM>),
wherein:
the wavelengths increase in magnitude in order from the medial extremity (<NUM>) to the lateral extremity (<NUM>).