Music performance involves continuous muscle activity of different body parts. Activity of more distal body segments which directly interact with the instrument usually relates to the actual production of sound. However, muscle activations of more proximal segments, including the trunk, might relate to the expressive content of the musical idea being communicated by the performer due to an embodiment process. This demo paper presents a work-in-progress implementation of an integrated set-up, the MappEMG, to produce a vibrotactile feedback based on surface electromyography data of pianists’ abdominal muscle activations. The main objective of the work is to make perceptible through haptic stimuli a rather non-visible dimension of pianists’ gestures (i.e. their ‘physiological tension’) linked to their expressive intentions in terms of musical tension, a key feature of musical structure in western tonal music. We envision to adapt the set-up presented to both live musical performances and pedagogical contexts.