I am undergoing physiotherapy for my knee injury (pain in the kneecaps) and aching soreness on the sides of my knees (bursitis). Part of my therapy is the use of TENS (Transcutaneous electrical nerve stimulation) and FES (Functional Electrical Stimulation). Some physiotherapists apply TENS first, then FES afterwards. But one therapist make me do both TENS and FES at the same time. Which is the correct or better approach?