For me, it seems to depend. With the BFST ankle I feel a light tingling sensation and not much warmth at all. Almost feels like pins and needles but not intense at all. With the BFST Back I don't feel much at all. The warmth is so slight, even at a level 3, that I regularly look at the controller to make sure it is still on. I definitely notice a difference afterwards though, as soon as it shuts off it feels instantly cool. Recently I have used the BFST Elbow and noticed slight warming at level 1, which felt soothing and comfortable. During the course of the treatment my fingers got a little "tingly" but that was about it. Regardless of what I felt during these treatments, the area I treated did feel looser afterwards. The most amazing recovery I had was with sciatica that was caused due to a tight piriformis muscle. In only 5 weeks I was back in commission with full range of motion.