Dear Idiot runner (you asked for it!),
There a couple of schools of thought on this matter. One school says that the marathon is such an extreme test, runners should set only the most conservative performance goal in their first. The other school says that any runner with half a brain can get a realistic sense of how fast he or she is likely to be able to run a marathon through the process of training and that it’s okay to use that realistic estimate as a goal.
I lean a little toward the first philosophy, perhaps in part because I set a goal that was too aggressive in my first marathon and wound up walking before 20 miles. I was an experienced runner, and a pretty decent racer at shorter distances, when I ran my first marathon, and it still took me to the woodshed. There are many examples of experienced runners who set a challenging goal and nailed it, or at least didn’t walk, in their first marathon, but there are many times more examples like mine.
And so far I’m only talking about experienced runners. New runners are much less likely to be able to run a marathon aggressively and avoid disaster. The less experienced you are (and you are a true newbie), the more you should be focused on simply finishing. In fact, even some of the wisest among the world’s best runners choose to focus on finishing their first marathon. This very afternoon I interviewed Shalane Flanagan, who holds three American records on the track and is currently training for her first marathon. I asked her what her goal is for the New York City Marathon and she said her primary goal was to finish.
Now, does that mean Shalane’s going to run 9:00 miles? No. She will probably start with the lead pack of women and stay with it. And in the back of her mind she will have a finish time that she is confident she could achieve on a good day with her best effort–a finish time that is not inconsistent with the pace of that lead pack.
In truth, relatively few people run marathons just to finish them. After all, if your goal is just to finish, won’t you then run the race as slowly as possible? I mean, if pace is not even a consideration… Almost everyone starts a marathon with some idea of the pace that’s appropriate for him or her. Even if you are being smart and planning to run your first marathon conservatively, you don’t really want to dawdle, do you? Of course not.
So this brings me to the point of actually answering your question about how to choose an appropriate time goal. There are two general ways to do that. First, if you are planning to run conservatively, you should choose a time goal that is consistent with the average pace at which you naturally run your long runs—especially the longest ones that fall closest to race day.
If you insist on chasing a “challenging goal,” I suggest you use Greg McMillan’s running calculator. This calculator can be used to predict your finish time in a marathon based on your actual time in a shorter race or time trial. If you have not run a race of any distance (recently), I suggest you visit your local high school track, warm up, and then run 25 laps (10K) around it as fast as you can, on the clock. Use your time with McMillan’s calculator to get a rough estimate of your marathon time.
Note that this prediction is unlikely to be on the money in any circumstance and will only even be close enough for horseshoes if you train appropriately for you marathon, pace yourself appropriately in it, and fuel yourself properly during it, and if the weather cooperates, etc., etc.