Abstract: The invention relates to a device and to a method for converting movement energy into heat. Movement energy is understood here to be the energy generated especially by the movement of people while running, riding a bike, riding a horse, etc. The heat is generated by two molded parts (1, 2), which are disposed one behind the other in the main direction of movement, at least one of which consists of a polymeric plastic and is movable elastically, and which are structured at their mutually facing surfaces so that, when the molded parts (1, 2) move one upon the other, surface friction, which generates frictional heat, results.