1A device for treatment of urinary incontinence comprises: at least one electrode, which is coupled to a pelvic muscle of a patient; and a control unit, which receives electromyogram signals from the electrode indicative of possible imminent incontinence, and which determines a threshold signal level that varies over time responsive to a condition of the patient, and which, responsive to a transient increase in the electromyogram signal above the threshold level, applies an electrical waveform to stimulate the muscle to contract, so as to inhibit the incontinence.