Yes, some patients experience muscle twitching as they increase the intensity of the treatment. Typically, the muscles in the treatment area, are held in comfortable tension during the treatment without any noticeable twitching. However, in some instances, for example on the elbow or on the front of the shoulder, you may feel a small amount of muscle twitching under the Pain Relief Pads - this is normal. If the muscle twitching is uncomfortable, you should decrease the intensity by pressing the MINUS (–) Button.