Yea... I really don't know about that. I know I'm nowhere near that weight, but I do 500lbs, and my legs come wayyyyyy further back than this guy ever made it. I had a personal trainer show me how, and these were definitely not a leg press, more like a tiny calf extension. Plus, you are NEVER supposed to lock your knees, which you did twice. Enjoy a knee blowout dude.