Running shoes on treadmill?

So its supposed to be a very low impact, recovery week for me. I feel fat, I am not, probably more lazy than fat...anyways...

I havent really used the elliptical machine in a few years for any real amount of time. Should I wear busted old shoes, or regular running shoes. Seems like unneccsary wear on running shoes. Not wearing out the sole but just breaking them down in general.

Thoughts?