It's a beautiful September day. There's a cool breeze blowing, not a cloud in the sky, and it's inspired you to lace up your shoes after taking a break from running all Summer. 

A few minutes into it, you start to experience an itchy sensation all over your legs, and it's so overwhelming that you have to stop running to scratch. What gives?

As your heart rate increases, blood flows faster, and the millions of tiny capillaries and arteries in your muscles begin to expand rapidly.

The capillaries stay open to allow for maximum blood passage when you're fit, but if you're out of shape, your capillaries tend to collapse, not allowing as much blood to pass through.

When your capillaries expand, the surrounding nerves become stimulated and send messages to the brain, which reads the sensation as itching. Unfortunately, your itchy legs are the price paid for falling off the exercise wagon. To prevent itchy legs, keep up with your regular exercise routine.