Can I Bank Some Time In A Marathon?

Running authors Bob Glove and Pete Schuder in Run Less Run Faster caution that if runners are more than two minutes faster than their target half-marathon split, they have blown ther marathon and will suffer for it over the last few miles.

Be safe, cautious, and plan your marathon.  Only about two percent of runners run the second half of their race in the same time as the first half.  It's easy to start out with fresh legs, a smile on your face and everything going your way.  But they don't call it marathon for nothing.  Pacing yourself is essential on long runs.  And even splits is the key.  For the marathon, you should strive to keep the disparity between the two halves less than 5 minutes -- for example, 1:39 for the first half and around 1:42 to 1:44 for the second half.

Take time to work on pacing.  It will pay off in the end.  And you'll get your just desserts.