So I am starting the C25k for a second time. I am a sedentary male 6'3 259lbs.The first time in week 2 day 1 I encountered bad knee pain to the point I couldn't walk, especially down stairs along with shin splints. I just started today again and the shin splints are full force. I have proper running shoes fit with orthotics after going to running store for evaluation. I am overpronated and my foot rolls bad while running which was corrected with my current setup. I stretch really good for 5 min before and after. I use a foam roller as well. I am always hydrated. I am not running fast at all, just a little faster than a brisk walk. Any idea what I am doing wrong? Getting pretty discouraged and I am trying to train for an Academy.
Also, I encountered something extremely weird for the first time in my life today. About 30 seconds into my first run, my legs, thighs, stomach, and ches twhere extremely itchy. It was under my skin feeling. It stopped as soon as I stopped running and started walking but it kept starting up again as soon as I started running. It was purely unbearable. Anyone familiar with this?
The only time I ever encountered anything close to that was in very hot weather during a very long run. The temp was in the 90s and I had no business running. I also felt close to blacking out, which you did not report, so I don't think your itch is heat-related. Perhaps exertion opens your pores and there is some discomfort because your body is not accustomed to this.
Then again, I wonder if your itching is more like a numbness due to a circulatory problem such as Peripheral Artery Disease (PAD) or Peripheral Vascular Disease (PVD) in the early stages. I think you should get clearance from a doctor before continuing to run. It's always a good idea to get clearance when transitioning from sedentary life to athletics anyway.
Other symptoms to look for are swelling, inability to sweat, low skin temperature in the context of exercise, or lack of sensation in the skin. These can help in your diagnosis and should be discussed with your doctor.
Sure, there could be things like allergies, and some have reported allergic reactions when running, but I don't think such a problem would start and stop with running the way you describe. I'm wondering if there could be a kind of benign hypoxia that sets in when your muscles start sucking up the oxygen from your blood. Running tends to shunt bloodflow from less critical areas like the skin to feed the muscles. After you become acclimated, you may experience better peripheral circulation so you can stay cool. In other words, this may be temporary, but better safe than sorry. Get some tests done, because this may not be as trivial as it seems.
The feeling of itchiness is an interpretation of nerve input that takes place entirely in the brain. For example, watching a video of ants crawling on someone's arm can make the viewer spontaneously itch. I don't think this problem is of that nature in your case, but you could try some mental tricks when starting out to see if you can control it. Music, reciting mantras, or other forms of self-hypnosis might get you over an exercise-induced allergic response. If you aren't thinking about it, don't expect it, and it still happens, it is probably real, and it is time for action.
In any case, any exercise you are cleared to do will eventually most likely help you more than sitting around, but you want to know your limits while you are waiting for those benefits to kick in. Don't give up, because this could be your wake-up call. Get checked, get cleared, and stay active!