The Infrex FRM and Infrex Plus use a form of electrotherapy referred to as "interferential therapy".  The concept is to use two flows of electrons, within the body, to create an "endogenous" current.   The outside current is simply the machine on,  two currrents generated, that meet at different points within the body and combined they allow the creation of a third, or inside the body, current which effects healing, reduces pain.  In quantum physics we can see and experiment with the physics of interferential therapy in an "in vitro" ( outside the body ) experiments and see certain results.  The problem with those associations is we are not seeing the biological side of the same experiment but with additional biological functions occurring which affect the outcomes. 

    The below video helps explain how interferential works in vitro from a quantum physics perspective.  The reason for the interest in the concept is to help explain the positive results seen in health care using interferential therapy.