Rocker structure (R1-R3) for a vehicle comprising a first steel profile (1) and a second steel profile (2) having the longitudinal direction (L) of the vehicle so that a channel (CH) is defined therebetween, the first and second profiles(1, 2) comprising a vertical central section (13), the rocker structure (R1-R3) comprising a first impact absorption element (3) arranged in the channel (CH), wherein the first impact absorption element (3) is a closed steel profile wherein an upper lobe (31) and a lower lobe (32) joined by a central joining section (33) are defined, the upper lobe (31) being located closer to the upper joining flanges (11, 21), the lower lobe (32) closer to the lower joining flanges (21, 22). The invention also relates to a method for obtaining the rocker structure and to vehicles provided with the inventive rocker structure.