Hi all,
Some really interesting stuff here, so I'll add my little bit of experience for what is worth. I've run 3 marathons now, last one 2 weeks ago, and always run negative splits...last one 1:35, 1:33. Personally I think it is about confidence...if your training has gone well, and you go in fresh, and from your training have a good idea what you can do, then trust yourself and do NOT go off too fast and get ahead of yourself...you WILL pay later, but stick to your pace, and trust yourself. If your are strong over the last 6m, then going past others is a tremendous feeling and carries you forward...the opposite is true if you have blown up and people are streaming past you. In my last marathon the last 10k was my fastest, and it can make a huge difference to your time, to keep pace or speed up...as opposed to losing perhaps 1-2 mins per mile as you struggle home can make 10-15mins difference overall.
So how do you do this...well long runs are key, you should be aiming for 5 good long runs 18-22. Plus a good medium run (10ish) mid week at a faster pace each week. Also make sure you rest well from 2 weeks before.
During the race drink and drink some more. I do carry my own bottle for 3 reasons, 1 I do it in training and it is no bother, 2, I can get a good drink whenever I want it, (I find it really hard to get much from cups other than a load up my nose!) and 3, I use an energy drink, and I think that helps...you can always add water from drink stations as well. Oh...and do eat...banana's, energy gels, whatever...as long as you do this in training and you stomach can take it...I'm lucky and I can.
So to all of you doing your first or just another one soon, good luck, it is a great effort, but the feeling at the end of achievment is worth it.