DIY Electro-Stimulation

Howdy there
Does anyone knows what are the specs (Voltage, Intensity, Pulse length, …) for stimulation of a muscle, like with those crappy QVC-stamped electro-stimulator ?
I just got a bunch of electrodes for ECG, those may not be the right kind of electrodes, but I’d like to test electrostimulation.

The only things I found are something called Weiss Law :
I = Rh(Cr/(t+1))
Where Rh = Rhéobase et Cr = Cronaxie (french PDF).
Didn’t go farther with that.
I’m browsing a forum about sexual electro stimulation, see if I can gain some infos.

Cheers

Quite some interestering topic… indeed… yet i am not quite sure if you can do this with just the Arduino…
I needed to get such stimulations of one of my arms for a while (as rehabilitation after an accident) and from what i learned there with my curious questions is, that it seems to be more than just pumping the muscles with charges.
To be really useful you need to apply an electric field that induces (right word here?) an action potential in the nerves that make the muscle move. So you would have to find out that, then you need to know where to place the electrodes and especially where not (you dont want accidently have an heartbeat like a hummingbird, do you? ;0)).
Soo the whole matter is quite interestering, yet i doubt if it is really doable…
but if it is - i’m the first to try, never had such a good muscle grow as i had in that time, although it is definetly a difference going from 40% muscle mass back to 100% than going from 100% to whatever…