From rec.running FAQ, part 2 of 8

Sore knees

(Elizabeth Doucette )

When running (also walking, and cycling), the inner most quad. muscle (inner part of thigh) does not get exercised as much as the other three quad. muscles of the thigh. If this inner muscle isn't strengthened by specific exercises, an imbalance of the muscles may occur. This can cause irritation of the underside of the kneecap (chondromalacia patellae) because the imbalance of the muscles can pull the kneecap towards the outside of the leg.

The kneecap (which has two convex faces on the back) rides in a broad indentation on the femur. Weak inner quadriceps (M. Vastus medialis) can pull the kneecap slightly out of its "track"; and it is theorized that this is what causes chondromalacia (which I believe is called patellofemoral pain syndrome these days). [edited for correctness 2/19/95 bylmm5 mail.cornell.edu (Lucie Melahn)]

I had chondromalacia patellae for a long time (and many of my running friends did too) but I haven't had problems since I've been doing specific exercises for my inner quad. muscle. It is tedious and boring but it works. I haven't had knee problems for about 3 years now :-). I should do this every day, whether I work out or not, but I don't always. If I feel any discomfort at all in my knees, I make sure I'm more diligent with this exercise and the discomfort always disappears. I'm always able to prevent a problem now.

The exercise is just a leg raise with the foot flexed and pointing away from the body. With this exercise make sure that your back is supported. As your quad. muscles fatigue, there is a tendency to help out with your back muscles. You may not realize that you're doing this until you notice later that your back is a little sore.

Sitting on the floor, bend one leg (like you're going to do a sit-up), bringing the knee towards the chest. The other leg is straight. Place your hands behind you on the floor to support your back. You can vary this by leaning against a wall and hugging your knee to your chest with both arms.YOU CANNOT BE TOO CAREFUL WITH YOUR BACK.

For ease of explanation, start with your right leg being straight and flex your foot (bring your toes towards your head, as opposed to pointing them away from you). Turn your leg to the right, so that your toes and knee are pointing to the right as far as possible. The position of the foot is important because it helps to isolate the inner quad. muscle. Now, do leg raises. When I started I could only do 10 or 20 before I needed to rest. Don't do the leg raises too quickly because technique is more important than speed. I now do three sets, each leg of 60 repetitions (alternating legs after each set) for a total of 180 per leg. It takes me about 10 minutes.

You can tell if your muscle is getting fatigued because it will start to quiver. Don't push it, change legs. Keep note of how many repetitions you do before you get fatigued and try to increase the repetitions next time. Compare you to you, not to others.