An electrotherapy apparatus comprising a sensor for detecting periodically recurring signal peaks, in particular the R-R peaks of an electrocardiogram of a person, a processor for deriving from the time interval between said periodically recurring signal peaks a time delay corresponding to approximately the end of the T-wave, and a trigger system initiated by an output signal of said processor or embodied within said processor for applying electrical stimulations to one or more active electrodes provided on the said person at a time related to the end of said time delay. The processor is adapted to generate, in addition to an initial electrical stimulation to induce muscle contraction, a plurality of further electrical stimulation pulses with intervals between each of said further electrical stimulation pulses, so that said further electrical stimulation pulses maintain said muscle contraction over a period extending from said initial electrical stimulation substantially up to a time just before a next expected R-peak.