Running even splits or negative splits is easy - as long as you run a fair bit slower than your best for the distance! Doing so when you are going for a personal best is a lot more difficult, and requires a combination of experience, patience, and guts, because the effort required to run an even paced marathon ranges from almost none at the start(in fact you have to hold yourself back it feels so easy) to hard by around 16 miles, to bust-a-gut tough over the last 2 or 3 miles. Its much much easier to just run at even effort which results in a steady decrease in speed, and even a drastic decrease in speed if you go off much too fast.
If you practice doing your long runs at only 10% slower than target pace, you'll find that the last 2 or 3 miles of the training runs is really hard, but you just manage to hang on to the pace, and that's exactly what you you want to build up the experience necessary to run even paced marathons.
I was a bit disappointed in my splits yesterday 1:29:20 and 1:30:18, I was trying for a slight negative split. Probably means that I was slightly over optimistic with my pace selection. If I had run the first half in 1:30 I would probably have been able to run the second in 1:29
Edited: 23/04/2012 at 17:41
