Originally Posted by Garrett Smith
Re: the difference between floor GHRs and the "machine" GHR.
Floor GHRs are much cheaper and more accessible to a larger population. That being said, I don't think flexing/extending the knee while the patella is being pressured against the ground (whether or not on a pad) is a good idea. Sounds like a perfect recipe for chondromalacia patella to me.
If I was going to add GHRs to my routine, I'd only go with the "proper" machine set-up, with the pad sitting on the front of the thighs (no pressure on the patella at all).
I used to do it on the ground with a funky setup. I loaded up a bar with 45's and some extra. I put some weights under it to keep the bar from moving from the wall. I wrapped 2 towels around the bar and had 4 mats to put my knees on. The setup worked just fine. No knee pain, except it's a hassle to setup, so I've stopped.
I also used to do it on a seated calf machine, which did cause some knee discomfort.