Jill, some folks actually
recommend squats for knee problems, especially patellofemoral pain syndrome or PF (I don't know what your actual problem with your knees is) . Check out Krista's site, here,
http://www.stumptuous.com/weights_index_revision.html
Here's a portion of what she says:
Quote:
Despite all that stuff about squats supposedly being bad for your knees, full depth squats are actually great for knee rehab. They strengthen all the leg muscles with a compound, natural movement. If you can squat without pain, then by all means do so, even if you can't use any weight. If you can't squat the full range, squat in the range of motion that is pain-free for you, and gradually try to increase the range. Front squats are an ideal exercise, both because they put more emphasis on the quads, and because they seem to put pressure differently on the knee joint. When I was having real PF problems, I could do full depth front squats with no difficulty whatsoever.
Some folks recommend leg extensions, but I am very hesitant to recommend these. Putting frontal/lateral as opposed to downward force along the shin (tibia) can actually worsen knee problems with the shearing force that is created in the joint. If you choose to do leg extensions, do them with very light weight, and only the top 1/3 of the movement (like from nearly straight leg to straight leg) and don't lock your knee.
I have chondromalacia patella, which refers to a wearing of the cartilage under the kneecap, and while I have to be careful, I find that doing squats does actually help strengthen them. The key is maintaining good form. The worse things I found for my particular problem is any movement that requires twist the knees quickly, especially with weight such as many movements done in aerobics and step classes. Squats done slowly and correctly doesn't hurt them.
Good luck with your weight training!