Richtig gute Sandsteinboulder.

Great tips! I'm a member of the bad knee club too, tkhnas to yoga, of all things. I generally walk or hit the elliptical for cardio, and my trainer has suggested weighted extensions, which I do regularly. When doing the leg extensions, it's important to fully extend, but not allow your knee to bend all the way back into resting. They're kind of like 1/2 extensions, where you never fully let your leg rest. They're great for strengthening the knee muscles, which hold your patella in place (good if you suffer from runner's knee).