The present invention relates to one-piece reinforcement elements consisting of an elongate shell-shaped basic body, the inner space of which has reinforcement ribs which are fixedly connected to the basic body, the reinforcement ribs consisting of plastic injection-molded on and their connection to the basic body taking place at discrete connection points via perforations in the basic body through which the plastic passes and extends over the surfaces of the perforations, and of a
rigid structure reinforcement which is appended from the same plastic, by means of the same injection-molded operation, at at least one end of the basic body and which corresponds essentially to the form of the cross section of the hollow profile to be reinforced at this point of a body, an expandable
adhesive material being applied over a portion of the surface of the
rigid structure reinforcement and of the elongate shell-shaped basic body, the form of the
rigid structure reinforcement and of the elongate basic body and also the quantity and distribution of the expandable
adhesive being selected such that the
adhesive material, during expansion, does not touch the inner surface of the outer panel of the
body cavity to be reinforced and touches and adheres to at least part of the other inner walls of the
body cavity to be reinforced, to the production of these and to their use.