Leo's main interests are in understanding electrophysiological events in the muscles and organs of the human body and their relationship to mechanical function. In particular he is interest in the recording and analysing signals from the gastrointestinal tract, heart, skeletal muscles, and uterus. He is also interested in developing methods for non-invasively recording and interpreting the weak electrical and magnetic fields that result from cardiac and gastrointestinal electrical activity.

Leo works closely with a number of international research groups based in the US (Vanderbilt University, Mayo Clinic, New York Institute of Technology, University of Louisville, University of Alabama at Birmingham, University of Michigan) and Europe (Université libre de Bruxelles, University of Stuttgart, Fraunhofer IPA and Fraunhfoer IZM).