if you are using warm & natural---you can pre-shrink it if you want to---if you do not want to---the more quilting you add the (flatter) the runner will remain- very little quilting allows lots of area to (shrink) lots of quilting keeps it flatter.
often i use either pre-washed inexpensive flannel or a very thin polyester batting in runners (polyester batting does not shrink) i still do alot of quilting to keep it all flat. w&n although a fairly flat batting does tend to 'shrink up' cause alot of crinkling...alot of quilting will help with that...my mom does not like the one runner i made her with w&n in it (the first one i made) i learned from there...& try different things...