An article of footwear, comprising: a sole member having an outwardly facing surface and an inwardly facing surface disposed opposite of the outwardly facing surface, wherein the outwardly facing surface is disposed further from a foot than the inwardly facing surface when the article of footwear is worn; the sole member having a vertical direction that extends between the outwardly facing surface and the inwardly facing surface; a protruding member assembly including a plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) connected together by a plurality of connecting portions (154; 1120); the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) further including proximal end portions that provide an inner surface (157; 1045) for the protruding member assembly and the plurality of protruding members including distal end portions (164; 1103; 1105) that provide an outer surface for the protruding member assembly; the sole member including a plurality of holes to receive the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) such that the distal end portions (164; 1103; 1105) of the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) extend away from the outwardly facing surface; wherein the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) can move relative to the sole member in the vertical direction; wherein the geometry of the inner surface (157; 1045) of the protruding member assembly changes as the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) move in response to forces applied to the outer surface of protruding member assembly, and wherein the connecting portions are elastic and characterised in that the connecting portions stretch as forces are applied to the outer surface of the protruding member assembly. a sole member having an outwardly facing surface and an inwardly facing surface disposed opposite of the outwardly facing surface, wherein the outwardly facing surface is disposed further from a foot than the inwardly facing surface when the article of footwear is worn; the sole member having a vertical direction that extends between the outwardly facing surface and the inwardly facing surface; a protruding member assembly including a plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) connected together by a plurality of connecting portions (154; 1120); the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) further including proximal end portions that provide an inner surface (157; 1045) for the protruding member assembly and the plurality of protruding members including distal end portions (164; 1103; 1105) that provide an outer surface for the protruding member assembly; the sole member including a plurality of holes to receive the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) such that the distal end portions (164; 1103; 1105) of the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) extend away from the outwardly facing surface; wherein the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) can move relative to the sole member in the vertical direction; wherein the geometry of the inner surface (157; 1045) of the protruding member assembly changes as the plurality of protruding members (152; 1102; 1104; 1131; 1132; 1133) move in response to forces applied to the outer surface of protruding member assembly, and wherein the connecting portions are elastic and characterised in that the connecting portions stretch as forces are applied to the outer surface of the protruding member assembly.