An article of footwear (12, 112, 312, 512, 1012, 1212, 1612, 1812, 1912) having a heel region, a forefoot region, and a peripheral region (22, 58); and comprising: a midsole assembly (10, 110, 310, 510, 1010, 1210, 1610, 1810, 1910) having: a fluid-filled bladder element (16, 1216, 1316, 1416, 1616) having a substantially arc-shaped heel portion and having a lateral arm portion and a medial arm portion spaced from the lateral arm portion, each of the arm portions (26A, 26B) extending from the heel portion, and the bladder element (16, 1216, 1316, 1416, 1616) configured to be positioned with the heel portion in the heel region and the arm portions (26A, 26B) extending from the heel region to the forefoot region along the peripheral region (22, 58); wherein the midsole assembly (10, 110, 310, 510, 1010, 1210, 1610, 1810, 1910) further includes a resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) secured to and resting on the bladder element (16, 1216, 1316, 1416, 1616) and having at least one protrusion (1021, 1821) descending into a cavity (1023, 1823, 1923) formed between the arm portions (26A, 26B); and wherein a first portion (1057, 1957) of the resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) adjacent an inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) is secured to the bladder element (16, 1216, 1316, 1416, 1616); and characterized in that a second portion (1059, 1959) of the resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) adjacent the inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) is spaced from the bladder element (16, 1216, 1316, 1416, 1616) in the absence of at least a threshold loading force and is configured to be moved into contact with the inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) under compression by the threshold loading force to attenuate the threshold loading force. a fluid-filled bladder element (16, 1216, 1316, 1416, 1616) having a substantially arc-shaped heel portion and having a lateral arm portion and a medial arm portion spaced from the lateral arm portion, each of the arm portions (26A, 26B) extending from the heel portion, and the bladder element (16, 1216, 1316, 1416, 1616) configured to be positioned with the heel portion in the heel region and the arm portions (26A, 26B) extending from the heel region to the forefoot region along the peripheral region (22, 58); wherein the midsole assembly (10, 110, 310, 510, 1010, 1210, 1610, 1810, 1910) further includes a resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) secured to and resting on the bladder element (16, 1216, 1316, 1416, 1616) and having at least one protrusion (1021, 1821) descending into a cavity (1023, 1823, 1923) formed between the arm portions (26A, 26B); and wherein a first portion (1057, 1957) of the resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) adjacent an inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) is secured to the bladder element (16, 1216, 1316, 1416, 1616); and characterized in that a second portion (1059, 1959) of the resilient midsole layer (18, 118, 318, 1018, 1218, 1818, 1918) adjacent the inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) is spaced from the bladder element (16, 1216, 1316, 1416, 1616) in the absence of at least a threshold loading force and is configured to be moved into contact with the inward-facing surface (80, 1280) of the bladder element (16, 1216, 1316, 1416, 1616) under compression by the threshold loading force to attenuate the threshold loading force.