I know of a couple of things it may be. The first one occurs when an increase of blood flow enters a body part or tissue level that has been fairly sedentary.The new blood flow can cause extreme itching and redness.Increased blood flow takes a short period of time to occur like increased heart rate, thus the delay in the reaction well into your workout. After you've gotten into a regular workout routine the symptomes generally go away. The other thing it might be is excercise induced allergy. Natural hystamines in your body are released during excercise and some people get an allergic reaction to them causing redness and itching. Some people even develope asthma like symptoms. Hope this might help.

This same thing happens to me. I think its the fat burning causing it to become irritated. This helped me,try not over exerting and take things more slow to get your body used to the running.

I have the SAME exact thing! All I do is I sit down for a few minutes and start running again, and try to bear with the itchy skin. I'm not sure what it is, I need to ask my doctor, but stldad seems like he already covered most of it.

ever since i was in the 7th grade i've had this problem also mine only occurs in the thigh muscle and you can't scratch it because it's below the surface of the skin and it happens when i walk, run, jump , jog any type of exercise to do with the legs i've found that basically punching my thighs relieves the itch i'm 32 now so i've lived with this for a while and the medical world is pretty cluless feels good to know ther are others

I've also wondered what the itching was! For me, its worse when I havn't exercised in a while...I also think its due to extra blood flow in my wobbly bits. I found that slapping areas that I know will itch before starting cardio help...just don't let anyone see you doing it! Vigorous rubbing would probably work just as well to get the blood flow started. I hope this helps you, I know the itching makes me so frusterated I want to stop. Once your body is used to working out the itch goes away, so don't let it stop you

Isn't this how it always goes?? People who love peanut butter are allergic to peanuts. People who just want to go for a run get severe itching soooooo bad that it'd almost feel better to just detach your legs from your body!! I've had this itchy leg thing for quite a while and I always felt so lame telling people that I couldn't run because of it. Its not that common and I always worry that people will think I'm just making up excuses. I've taken allergy meds before working out and I've worn special pants and neither worked. This is the only thing that has worked--in college I was motivated to hit the gym every night for long periods of time just to gaze at a gorgeous upperclassmen who also worked out every single night. Because I was there for so long and wasn't necessarily in for an intense work out I'd really take my time...1/2 hour of slow-moderate peddaling on the bike followed by 1/2 hour of walking-light jogging on the treadmill. The itching would still happen but I was able to stick it out. After keeping up that exercise routine for about 3 months the itching just went away. I'd be able to workout and do an intense/quick run on the treadmill without an ounce of discomfort. The hard part is that once you stop running on an extremely regular basis the itching comes back full force! I've also noticed that the older I get, the less willing I am to put up with it and I'm more apt to throw the towel in and forget about running altogether. Sad to say, but so far, I haven't found the quck fix for my itchy legs and I don't have the time to spend and hour or more per day just warming my legs up.

I've also experienced this! I just started running again after 2 years. I had forgotten about the itch, and there it was again, the first time I started to get my heart pumping & blood flowing. For me, the itch tends to be on my torso, mostly stomach and back. I have had it on my thighs before as well. Very strange and annoying!

Same thing has happened to me for years. I get itchy on my torso and thighs. I ran track in middle and high school and never got any relief from it. I just stuck it out, knowing that it would go away within minutes after I stopped running. Less impact-related sports like riding a bike doesn't cause the itch, so I usually just stick with that.