Well, not an expert, but, I had one, didnt keep it to long, sent it back, but, my reasons were not because it did not work. I used in very little, but, when I did I really could feel it in the abs , problem was - If you do not have real good wrists, cant do it. I have carpel tunnel and it drove my hands and wrists nuts. You have more weight resting on the wrists than you realize and I could just not keep on doing it. Hope this is of some help.