Grrr.... I think I have patellar tendonitis. Here's the long story: I began doing squats and lunges back in August. My chiropractor warned me that they could hurt my knees, I countered with a bunch of info that squats were not bad for knees, and we came to an agreement that I would skip the lunges and not squat with heavy weight, at least not for a while. One day after seeing him (last month) my right knee began to hurt. Now they both hurt. The pain is below the knee, at the top of the tibia. After reading about it, my best guess is patellar tendonitis, although chondromalacia is also a possibility (I have no clicked or grating in my knees, though).
I stopped all lunges and squats. At the same time, I began doing the Body by Science workouts, and started heavy leg presses. That aggravated my knees. I decided to try static contraction leg presses (much more weight with very little range of motion, hold the weight steady). This confused me. The first time I tried this, I upped the weight more and more until the plates weren't even numbered any more. Counting the plates, I was up to 410 pounds, and it didn't feel like my legs were really working. My back didn't like it, and I was almost being pushed up out of my seat, so I stopped. The next week I gave it another try, and held 410 pounds for 2 minutes. My knees hurt a lot later that day. I had also done tabata sprints on a recumbent bike, which I suppose could have aggravated them too.
Sorry for the long post. I want to work my legs, but how???