A sole assembly (10C; 10D) for an article of footwear comprising: a sole plate that has a foot-facing surface with a recess in the foot-facing surface; an insert plate disposed in the recess; wherein the insert plate has an anterior end, a posterior end, and a length extending between the anterior end and the posterior end that is less than a length of the recess, such that the insert plate flexes free of compressive loading by the sole plate when a forefoot portion of the sole assembly (10C; 10D) is dorsiflexed in a first portion of a flexion range, and operatively engages with the sole plate when the forefoot portion of the sole assembly (10C; 10D) is dorsiflexed in a second portion of the flexion range that includes flex angles greater than in the first portion of the flexion range; wherein the first portion of the flexion range includes flex angles of the sole assembly (10C; 10D) less than a first predetermined flex angle (A1B) and the second portion of the flexion range includes flex angles of the sole assembly (10C; 10D) greater than or equal to the first predetermined flex angle (A1B); and wherein the sole assembly (10C; 10D) has a change in bending stiffness at the first predetermined flex angle (A1B); and characterised in that a resilient material is disposed in the recess between the sole plate and at least one of the anterior end of the insert plate and the posterior end of the insert plate, wherein the resilient material has a compressive stiffness less than that of the insert plate, such that the resilient material is compressed prior to operative engagement of the insert plate with the sole plate when the sole assembly (10C; 10D) is dorsiflexed, bending stiffness of the sole assembly (10C; 10D) thereby being at least partially determined by a compressive stiffness of the resilient material at flex angles less than the first predetermined flex angle (A1B), wherein the resilient material is in a maximum compressed position at the first predetermined flex angle (A1B), and wherein the sole assembly (10C; 10D) is adapted to transfer compressive forces of the sole plate through the resilient material to the insert plate, such that the insert plate is operatively engaged with and under compressive loading by the sole plate at the maximum compressed position of the resilient material. a sole plate that has a foot-facing surface with a recess in the foot-facing surface; an insert plate disposed in the recess; wherein the insert plate has an anterior end, a posterior end, and a length extending between the anterior end and the posterior end that is less than a length of the recess, such that the insert plate flexes free of compressive loading by the sole plate when a forefoot portion of the sole assembly (10C; 10D) is dorsiflexed in a first portion of a flexion range, and operatively engages with the sole plate when the forefoot portion of the sole assembly (10C; 10D) is dorsiflexed in a second portion of the flexion range that includes flex angles greater than in the first portion of the flexion range; wherein the first portion of the flexion range includes flex angles of the sole assembly (10C; 10D) less than a first predetermined flex angle (A1B) and the second portion of the flexion range includes flex angles of the sole assembly (10C; 10D) greater than or equal to the first predetermined flex angle (A1B); and wherein the sole assembly (10C; 10D) has a change in bending stiffness at the first predetermined flex angle (A1B); and characterised in that a resilient material is disposed in the recess between the sole plate and at least one of the anterior end of the insert plate and the posterior end of the insert plate, wherein the resilient material has a compressive stiffness less than that of the insert plate, such that the resilient material is compressed prior to operative engagement of the insert plate with the sole plate when the sole assembly (10C; 10D) is dorsiflexed, bending stiffness of the sole assembly (10C; 10D) thereby being at least partially determined by a compressive stiffness of the resilient material at flex angles less than the first predetermined flex angle (A1B), wherein the resilient material is in a maximum compressed position at the first predetermined flex angle (A1B), and wherein the sole assembly (10C; 10D) is adapted to transfer compressive forces of the sole plate through the resilient material to the insert plate, such that the insert plate is operatively engaged with and under compressive loading by the sole plate at the maximum compressed position of the resilient material.