In a method for the detection of local displacements and rotations, a sum signal and additionally a difference signal are formed from two separately generated signals of two transducer elements, which are spaced from each other, and subsequently the formed sum signal and the formed difference signal are OR-operated. An apparatus of the present invention can be a treadmill sled having a frame, a rotatable continuous belt mounted on the frame, the belt presenting an upward directed support surface for supporting a user athlete, a training apparatus, and a performance measuring system. The helical coil has a first turn with its front edge at least substantially aligned with the yoke tip. A bridge may also be provided to support the cylinder head. In response thereto, the object is migrated therebetween.