An athletic shoe sole for a shoe has side portions with concavely rounded inner and outer surfaces, as viewed in at least a heel area and a midtarsal area of the shoe sole. Arranged in the mixing vessel in alignment with the inlet opening and axially adjustable in relation to the inlet opening is at least one movable mixing element to mix the polyurethane component fed into the mixing vessel with gas injected into the polyurethane component via a nozzle. A current sensing resistor produces a voltage drop representative of a current delivered to a load by the integrated power transistor. The stator includes a recess at each extremity of a diameter.