Heh, was wondering what a post with my name on it could possible be about. Ankle weights in theory and in 'some' practice aren't bad, just in some cases like mine they can have negative results.
It happened a few years ago, my 1st or 2nd year out of high school during the winter break. I had been running regularly for a few months, when my sister had come back into town we even got through a 9 mile session. So after she left I was feeling pretty good and didn't feel like losing any ground. So on my 3 mile route I started wearing ankle weights. I ran this three times, nothing felt wrong(no pain). A day or two after the third 3 mile run, I decided to run for 45-60 minutes without them. Just a nice easy long run. 30 minutes in my knees to started to feel a bit funny, perhaps this would have been the optimal time to stop(but I was still kind of far from home) so I kept running. 10 minutes later my knees were on fire, and I was still trying to jog(it was one of those times where I think I was actually jogging slower than a walk). So I finally stopped and walked home. At this point my knees were wanting to lock up, and it was extremely painful to move them. They felt like this for the next three days of just ordinary movement.
A week goes by and my knees stop hurting just from normal movement(I usually tend to avoid going to the doctor right away, I should have gone earlier in this case). So I decide to try to jog a little, couldn't even get off my street before my knees were in pain(small street by the way). At this point I'm thinking I might have done something stupid. So I get the name of some kind of doctor(don't remember exactly which), get an xray and then go to a sports doctor of some type. Xray didn't really show anything wrong and the first doctor said something about cartilage. The sports doctor on the other hand said it looked like there was a muscle imbalance involving my patella and the way it glides. It was most likely either caused or aggravated by the ankle weights.
While using ankle weights with things like the jump rope isn't bad, just about any doctor I've talked with about it and the information I've seen after the fact shows that altering your natural running form is a bad idea. While the weight of 3-5 pounds per leg is really insignificant, when it's attached to the bottom of your leg you do use your muscles differently. Would it have been better to wear a belt with weights, maybe. A little for that now. I didn't follow my therapy to much so it took me a long time to get back into running condition.
Morals of the story. If you're trying anything new, you should probably consult some sort of knowledgeable doctor in the field. For the kiddos still in school, go ask one of the sports trainers. Don't mess with your natural running form for extended amounts of time. If in pain, it's a good idea to stop B)