It seemed inevitable, and I have my funniest race stories from the miles after hitting the wall. For example, in Toledo I realized that after 22 miles, I can't count backward from 80 to 0. At the Martian, I completely put my dignity on the shelf and sang aloud, knowing I have the world's worst singing voice, and knowing full well that other runners were laughing / cringing at me.
The great Hal Higdon says:
There is no perfect distance for the long run. Twenty miles is the peak distance used in most training programs, if only because 20 is a round number. That is the longest run I suggest to runners using my training programs, even advanced runners. But in countries outside the United States, 30 kilometers (18.6 miles) is equally round and as frequently used. Most coaches feel that once you reach 16 miles, you are in long-run territory. That is the point where the psychological and physiological changes kick in.He also says that miles 20-26 should only be run on a race course, wearing a race number. I have to respectfully disagree with him on this point. My training this summer had two distances past 20 - 20.11 and 21.64, and I was able to keep going at the Free Press marathon, without running headfirst into THE WALL. Sure I was tired, but the upper miles arrived quickly and while I was tired, I had my full mental capability at all times. It could be, though, that I knew the course. It's one thing to know I have 4 miles left. It's completely different to know I have to get off the island, turn left on Jefferson, go by the RiverWalk, turn right, turn left and done!
My next training program I'd like to bump the longest run to 22 miles and see if it lends itself to more time consistency at the end. It's a hypothesis worth testing :)