Abstract: In a biofeedback device adapted for sensing position of the Transverse Abdominis Muscle (TAM) on small excursions of the abdominal wall including a sensor which changes resistance on a change in dimension thereof in any direction. The sensor element includes a plurality of interlaced electrodes in juxtaposition with a resilient antistatic device. A particular implementation is in the form of a two pole sensor incorporated into a bio-feedback monitor. The sensor is physically attached to the monitor which can be worn on the belt or at or near the waist line. A lever on the back of the monitor rests against the body and engages the sensor comprising a variable resistance foam component. Pressure exerted against the lever, when the TAM is relaxed causes a change in the resistance which energizes the electrical circuit above a given threshold and causes a variable pitch sound to be generated or alternatively drives an electrical vibrator motor at a variable speed.