Abstract: An article of footwear with a heel region including a posterior end of the article of footwear, a mid-foot region, and a forefoot region including an anterior end of the article of footwear; a lateral side, and a medial side opposite the lateral side; an upper; and a sole structure coupled to the upper. The sole structure has a midsole with a first cushioning element extending from the posterior end to the anterior end; a second cushioning element extending from the mid-foot region to the posterior end, the second cushioning element being formed of a different material than the first cushioning element; and a shell with a plurality of circumferentially-spaced apart protrusions, wherein each of the plurality of protrusions is directly coupled to the second cushioning element.

Abstract: An article of footwear comprises an upper and a sole structure secured to the upper. The upper includes a side portion that has a first material composition at an exterior surface of the side portion. The exterior surface has a first coefficient of friction. The sole structure has a second material composition at an exterior surface of the sole structure that underlies the side portion of the upper. The exterior surface of the sole structure has a second coefficient of friction. The first coefficient of friction is substantially equal to the second coefficient of friction.

Abstract: An article of footwear comprises an upper and a sole structure secured to the upper. The upper includes a side portion that has a first material composition at an exterior surface of the side portion. The exterior surface has a first coefficient of friction. The sole structure has a second material composition at an exterior surface of the sole structure that underlies the side portion of the upper. The exterior surface of the sole structure has a second coefficient of friction. The first coefficient of friction is substantially equal to the second coefficient of friction.

Abstract: An article of footwear comprises an upper and a sole structure secured to the upper. The upper includes a side portion that has a first material composition at an exterior surface of the side portion. The exterior surface has a first coefficient of friction. The sole structure has a second material composition at an exterior surface of the sole structure that underlies the side portion of the upper. The exterior surface of the sole structure has a second coefficient of friction. The first coefficient of friction is substantially equal to the second coefficient of friction.

Abstract: An article of footwear comprises an upper and a sole structure secured to the upper. The upper includes a side portion that has a first material composition at an exterior surface of the side portion. The exterior surface has a first coefficient of friction. The sole structure has a second material composition at an exterior surface of the sole structure that underlies the side portion of the upper. The exterior surface of the sole structure has a second coefficient of friction. The first coefficient of friction is substantially equal to the second coefficient of friction.