Video looks back at the different types of electrotherapy devices and the wave forms used by each. The video explains the results seen in healing bed sores, non union bone fractures, and interferential therapy for pain. The choice and evolution of electrotherapy is explained so the viewer can understand how electrotherapy devices have emerged for the various therapies now available. With over 35+ years of experience the video is a walk back through time with Bob Johnson and how the latest Infrex FRM machine has evolved and why. The theory of electron supplementation and electron distribution is illustrated.