Core work has crossed my mind, but I have not incorporated any of it yet into my training. I do need it--abs and back both could use some shoring up. Any suggested regimens that work for you? I will look into when the neighborhood clubhouse is open--it has some Universal weight machines, a few dumbbells, and other assorted items. I have some push-up handles that need to be dusted off, too.
For my prior 12-hour walks, I can't remember doing much regarding nutrition...I think I had some PowerBars and Gatorade, and I purchased a hamburger or two to eat. At the end of them, my quads felt like they were put through a shredder, but that was when I was doing very little running at all, and about 20-30 extra pounds ago. The race organizers will provide water, sports drink, bananas, pretzels, chips, and cookies...and I was thinking about making several PBJs, Rice Krispie treats, and some salted boiled potatoes as supplemental items. I have even thought about bringing a jar of dill pickles and putting small amounts of pickle juice into some Gatorade if the weather becomes hot (quite possible for St. Louis on September 2nd, the day of the race). I sweat quite a bit and lose a lot of minerals (on a 9-mile run yesterday in cool conditions, I still had the tell-tale white salt-like residue on my singlet and on the sides of my face), so I will experiment this spring and summer with that concoction to see if that helps keep the electrolytes in balance.
I will also have to think about how often to walk...the event is run on 1.4-mile paved loops. It begins at 7:30 a.m., and I was considering walking one loop every hour while the temperatures would be at their coolest--say, for the first 2-3 hours of the ultra. Right now, I'm running 12-minute miles at a relaxed pace, so that would mean a 3:1 or 4:1 ratio of jog loops to walk loops to start. Then, I could start reducing the ratio to 3 jog/2 walk loops or 1 jog/1 walk according to how I feel later in the day.
I will read the article that you cited--I am eagerly reading about this ultra world and gleaning all that I can from the books and articles I come across. It is kind of scary to think about participating in a 12-hour event, but after running 6 marathons, I'm itching to do something different. That is making the preparation fun!