The smith machines I have used never made any such mandate. You position your feet. Just make sure that in squatted position the bar is in line over your quads. Try drop setting squats on the smith and then tell me machines do not stimulate muscle growth.
True, you do position your own feet but the unnatural descent caused by the fixed plane of the machine was what I am placing emphasis on. It is not a NATURAL movement. Natural biomechanics would suggest that since the machine is in a fixed location the feet would need to compensate for that in their positioning.
Put the back of your ankles against the wall and try touching your toes without bending your knees. This is analagous to the smith machine squat. It forces your body to do something it wasn't intended to do and not in a good way.
There is a natural curve associated with the descent of the bar in a back squat and the smith machine doesn't take that into consideration. It is not safe for back or knees period.
I will not argue the fact that they build muscle because the potential is there but why half ass it? Just go ahead and do a free weight squat which utilizes so many more stabilizers and auxiliary muscles and to a greater degree.
Most people don't or won't because its too much work. I've never seen a powerliting competition that used a smith machine for squatting before either.
I'm not trying to be a know-it-all or anything like that but I am saying all of this out of personal experience and what I know from basic kinesiology. If I ruled the world I would dismantle all smith machines because *I believe* they're unsafe LOL.
:squat: