I never even heard of this until at my quilting group yesterday. One of the ladies — about 82 years old — has one and she swears by it. She is more spry and in better shape than before, according to her.
Well, I ain't quite that age yet (74), but I can attest to both and add "in less pain". I am amazed that a technology so effective is so little known. I've let a number of people use my machine who have later bought their own, and ONE HUNDRED PERCENT of them say it has made a positive difference.