I just saw one of these commercials for those ab zapping electrocution dealies. What principle do these things work off of? The reason I ask is because most of the stuff that we see on TV is a crock some of the weirdest excersize equipment turns out to be legitamit. Example a couple of years ago I saw and add for some flexing bow thing that you are supposed to just jiggle. I looks like a leaf spring off a car/truck that flexs. Anyways a year later a physical therapits told me that surprisingly those bow thingees are acutally good for building isometric strength. So these electric shock ab things...what do they do and is it legitamite? Thanks.