I'm just starting week 3 of phase 2 and I've been doing doubles for a couple weeks now. My legs were pretty tired at first, but I'm adjusting well with one exception. I seem to have persistent soreness on the outer part of my lower legs, maybe 3-4 inches above my ankles. It also seems like it gets a little aggravated after wacky jacks on Cardio X where my legs are going side to side and all the pressure is put on one leg at a time.

It's nothing more than an annoyance right now, but I was just wondering if I should take any precautions about it. The pain isn't really bad, I just don't want to end up screwing up a tendon or something that'll keep me away from P90X.

it's hard to diagnose your exact problem and I am no doc but it may be shin splints (which I have suffered from for years while playing soccer and ultimate).

Here are three common spots for shin splints:


Here are a few links:
http://www.medicinenet.com/shin_splints/article.htm
http://en.wikipedia.org/wiki/Shin_splints
http://www.mayoclinic.com/health/shin-splints/DS00271

hope this helps.