Can't say much without seeing you use said piece of equipment. Did you suffer a meniscus tear, or other serious knee injury that keeps you from squatting?
I've been doing a mixture of Back extensions and GHRs because my knees are bad and I can't do squats. I've been doing them on this slanting bench:
http://www.fitbiz.com.au/FITBIZ/clie...=47&prodID=366
As you can see, the bench is slanting. So, I basically do a back extension and then I go up as high as I can so that it starts to look more like a GHR. Now, a monitor in my gym said that this would damage my back. I want to know what you think about this.
Can't say much without seeing you use said piece of equipment. Did you suffer a meniscus tear, or other serious knee injury that keeps you from squatting?
Here it is:
Will this hurt my back?
Only if you do it right.
I would recommend that you go a little slower and keep your back in extension the whole time. However, given that these are unweighted and done on a 45-degree bench, your risk of injury is pretty damn low, even if you don't take my suggestions.