How do you flatten a four-pack?

First, I'm girl and I'm a runner. Somehow over the past year I've built up a four-pack and it's a bit bulky. Is there a way to flatten and lengthen out my abs so that instead of the visible muscles, you can see just the line down the middle? like this, if possible: a href="http://www2.victoriecret.com/commerce/onlineProductDisplay.vs?namespace=productDisplay&origin=onlineProductDisplay.jsp&event=display&prnbr=CM-232982&page=1&cgname=OSSWMSASBKS&rfnbr=6061" rel="nofollow"http://www2.victoriecret.com/commerce…/a