How? My gym doesn't have them, I usually do it on a hyperextensions station but backwards. Any ideas?
I've done them like that while holding a dumbbell between my feet. I've also done them off a Swiss ball.
this is exactly what I do and its fine.
That's like doing a clean w/o a bar. Don't even bother. Stick with RDL's, conventional deads, back extensions, or similar. Using a DB between the feet is very limited in terms of load and ROM
I'm trying to picture this...are you getting in the hyperextension thing upside down?
I do them at home by putting a bench on top of a couple of boxes. These boxes should be high enough that your feet don't hit the ground. Lie down on the bench in the reverse hyper position and hyper away! For extra weight, I strap weight between my ankles with an ordinary jean's belt. You hmay have to put a counter weight on the front of the bench, otherwise it may tip.
I currently use this with 50kgs strapped between my legs for 4 sets of 10. It's not as good as a reverse hyper machine, but it will do until I can get one.
If you have a power rack, either mindeffer01 or mertdawg have a set up that is better than mine. PM them for details.