My August 2006 half-marathon and the one I just finished on April 21, 2007 have one trait in common. I ran a pace about a minute and a half faster than my training runs for 8-9 miles, and then I bonked and had to slow down; my body wasn't used to that fast pace. However, during the 8-9 miles, I felt comfortable. I need to extend that comfortable feeling out to 13.1 miles and then (later on) to 14 or 15 miles.
I've been thinking about the best way to become comfortable with the faster pace. It seems I have two options.
1. Continue doing what I've done for the past six months. Run 30-33 miles/week and slowly increase my speed. That would probably give me a small improvement by October similar to the one I had in the race yesterday.
2. Immediately increase my comfortable pace to 10:30 and decrease all of my distances to be less than 8 or 9 miles. Hopefully, I could do this without a lot of time involved, because that is the distance I felt comfortable with in both half-marathons. I would still run four times per week (2 rest runs, a medium run, and a long run), and I would slowly increase my medium and long runs to the distances they are now. That is, I would start with runs of 5, 5, 8, 8 (26 miles per week), and I would slowly increase my medium run to 10 miles and my long run to 13 miles. If I couldn't handle the 26 mpw and the faster pace, I would reduce the runs to what ever level I could handle.
Option 1 is probably the safest option, but it would give the smallest improvement in the six months between now and the World Senior Games in October. Option 2 would likely give a bigger improvement in October, but it would probably put more stress on my body. I'm thinking I'll experiment with option 2 and see how it goes. If I have difficulty with it, I can always switch to option 1. I'll be my normal conservative self during these tests so I don't become injured.