Abstract: A supporting element having a rigidity which may be adjustably controlled includes a cover (29) and a filler (30). The filler includes a flexible laminated structure having a plurality of layers (31, 32, 33; 32a, 32b; 34) which are mounted to be moveable relative to one another under the effect of a non-uniform distribution of force compressing the filler in the absence of a controlled pressure. The cover (29) is coupled to a vacuum source and is adapted to receive a controlled pressure to make the supporting element more or less rigid. When the cover (29) has a predetermined inner pressure, the relative displacement of the respective layers is prevented thereby giving the layers a predetermined rigidity. The layers may have a device for immobilizing the layers distributed on either side of at least one compressible layers (32, 32a, 32b).