What were those bogus 50's weight-loss machines called?

Sometimes in movies set in the 50’s to 70’s, you see people on these machines in the gym. They look like treadmills, but they have this vibrating belt that goes around the waist and just vibrates and vibrates. What were those things called?

Obviously, this would never actually get you into better shape, so why in the hell did people use them? After using it for 2 months and not noticing any results whatsoever, why would someone continue to use it? Wasn’t anyone pointing out that they were phony weight-loss methods?

My good friend’s Mother had one, being about 10 years old at the time I called it a vibrator. Much hillarity must have occured when I talked about the large vibrator she kept in the garage to other older people.
Sorry but I really don’t know the propper name, but wouldn’t it at least give a reasonable localised massage effect which might help tone up the area in a similar way to a Jakuzi does.

According to http://shop.store.yahoo.com/carbsmart/devices.html, they were called hip shakers.

I don’t think Jacuzzi has ever made a claim that their product “tones” and it is certainly not verified that massage belt vibrators do so.

You often see these devices on infomercials too, as an example of crazy, ineffective ways people try to lose weight. Then, the informercial spends 30 minutes arguing that a device that administers electric shocks to your abdomen is a non-crazy, non-ineffective (and quick and easy) way to lose weight.

It’s apparently called a ‘vibrating belt’. I found only a few Google hits with this term, though. This one is a humorous account of the history of these machines and how they work, which might give some insight into how people in the past thought they worked. (Note: the article is a ‘hoax’.)

I’m not sure, but in the very last Seinfeld episode, when you see Newman leaving his apartment to go watch the trial, there’s an odd looking machine by the apartment door. You can only see it for a split second, but I think it’s one of these machines.

Did anyone get a better look?