Article of footwear with fluid-filled element

1. An article of footwear comprising:

an upper;

a sole structure disposed below the upper and configured to engage a ground surface, wherein the sole structure includes a fluid-filled element located in a heel region of the article of footwear, wherein the fluid-filled element includes: (a) an upper surface, (b) a lower surface, and (c) an outer peripheral surface extending between the upper surface and the lower surface, wherein the outer peripheral surface extends in a horizontal direction continuously from a medial side of the article of footwear around a heel portion of the article of footwear to a lateral side of the article of footwear,

wherein the outer peripheral surface includes a convex curvature extending from the upper surface to the lower surface so as to define a lower edge undercut portion that extends from the medial side of the article of footwear, around the heel portion of the article of footwear, to the lateral side of the article of footwear, and

wherein the fluid-filled element includes a pair of voids that are spaced apart from one another and extend through a central region of the fluid-filled element from the upper surface to the lower surface such that each void of the pair of voids is exposed at the upper surface and exposed at the lower surface, and wherein a first void of the pair of voids is located closer to a forward end of the fluid-filled element than a second void of the pair of voids, and wherein the first void and the second void are both substantially U-shaped with an open portion of the U-shaped void oriented toward the forward end of the fluid-filled element.

2. The article of footwear of claim 1 , wherein the fluid-filled element is thermoformed from two sheets of polymer material.

3. The article of footwear of claim 1 , wherein the fluid-filled element further includes: (a) a first vertical recess defined in a lateral side of the outer peripheral surface of the fluid-filled element and extending from the upper surface to the lower surface of the fluid-filled element, and (b) a second vertical recess defined in a medial side of the outer peripheral surface of the fluid-filled element and extending from the upper surface to the lower surface of the fluid-filled element.

4. The article of footwear of claim 1 , wherein the lower edge undercut portion of the fluid-filled element is exposed in the sole structure.

5. An article of footwear comprising:

an upper;

a sole structure including a fluid-filled element located in a heel region that is exposed on both a lateral side and a medial side of the article of footwear, wherein the fluid-filled element includes: (a) an upper surface, (b) a lower surface, and (c) an outer peripheral surface extending between the upper surface and the lower surface;

wherein the outer peripheral surface of the fluid-filled element includes a first pair of vertically oriented recesses on the lateral side of the article of footwear and a second pair of vertically oriented recesses on the medial side of the article of footwear, and

wherein each recess of the first pair of vertically oriented recesses and the second pair of vertically oriented recesses extends from the upper surface of the fluid-filled element to the lower surface of the fluid-filled element;

wherein the fluid-filled element includes a first channel that extends through a central region of the fluid-filled element from the upper surface to the lower surface such that the first channel is exposed at the upper surface and exposed at the lower surface;

wherein the fluid-filled element includes a second channel spaced apart from the first channel that extends through the central region of the fluid-filled element from the upper surface to the lower surface, and wherein the first channel is located closer to a forward end of the fluid-filled element than the second channel; and

wherein the first channel and the second channel are both substantially U-shaped, and wherein each of the U-shaped channels has an open portion oriented toward the forward end of the fluid-filled element.

6. The article of footwear of claim 5 , wherein a forward end of the fluid-filled element includes a fluid fill tube.

7. The article of footwear of claim 5 , wherein the fluid-filled element is thermoformed from two sheets of polymer material.

8. The article of footwear of claim 5 , wherein each vertically oriented recess of the first pair of vertically oriented recesses and the second pair of vertically oriented recesses has a generally cylindrical concave shape.

9. An article of footwear comprising:

an upper;

a sole structure including a fluid-filled element located in a heel region that is exposed on a lateral side, and on a medial side of the article of footwear, wherein the fluid-filled element includes: (a) an upper surface, (b) a lower surface, and (c) an outer peripheral surface extending between the upper surface and the lower surface,

wherein the fluid-filled element includes a pair of voids that are spaced apart from one another and extend through a central region of the fluid-filled element from the upper surface to the lower surface of the fluid-filled element such that each void of the pair of voids is exposed at the upper surface and exposed at the lower surface, and wherein the pair of voids are both substantially U-shaped, and

wherein a first void of the pair of voids is located closer to a forward end of the fluid-filled element than a second void of the pair of voids, and wherein both the first void and the second void have an open portion of the U-shaped void oriented toward the forward end of the fluid-filled element.

10. The article of footwear of claim 9 , wherein the outer peripheral surface of the fluid-filled element further includes a first pair of vertically oriented recesses spaced apart from each other on the lateral side and a second pair of vertically oriented recesses spaced apart from each other on the medial side.

11. The article of footwear of claim 10 , wherein each recess of the first pair of vertically oriented recesses and the second pair of vertically oriented recesses extends from the upper surface of the fluid-filled element to the lower surface of the fluid-filled element.

12. The article of footwear of claim 10 , wherein each recess of the first pair of vertically oriented recesses and the second pair of vertically oriented recesses has a generally cylindrical concave shape.

13. The article of footwear of claim 9 , wherein the fluid-filled element is thermoformed from two sheets of polymer material.

14. The article of footwear of claim 9 , wherein the forward end of the fluid-filled element includes a fluid fill tube.