I've had them for about 3 years now..mainly in legs on and off. Dont have pain or loss of muscle functions. I do get calf cramps at night but associate this with back pain, hamstring tightness and certain exercises I perform. I have had testing for these. Most importantly EMG and head MRI. These would have determined if I had critical diseases such as ALS etc...I just deal with them. Some days are better than others.