Device and method for generating brief strong current pulses in a coil for generating magnetic field pulses which according to the electromagnetic induction principle induce stimulation currents in the body tissue triggering an action potential of the nerve and/or muscle cells, where the coil is positionable close to the body tissue to be stimulated so that its magnetic field passes through the body tissue, and where the device comprises a power generating unit that can generate a freely selectable temporal course of the current through the coil during the current pulse. A method for determining an optimized temporal course of a brief strong current pulse through the coil, where the temporal course of the current pulse is calculated using a method which numerically simulates the electrical behavior of nerve and/or muscle cells and the coil and optimizes the course of the current pulse regarding at least one parameter, or which by means of stimulating the nerve and/or muscle cells with predetermined current pulses optimizes the temporal course of the current pulse regarding at least one parameter and therefrom determines essential parameters of nerve and/or muscle cells.