I am slated to run the Stillwater (MN) Marathon on May 29th, three weeks before Grandma's Marathon and use it for training run. I can appreciate that many of you may question this move.
There are currently two schools of thought. One says that there is no need to run more than a 20 miler before running a marathon of 26.2 miles. In training, if a runner can get to the point of a couple of 20 milers, both done two to three weeks apart, with the last one at least three weeks before the marathon, then that is all the training that is needed for the long run(s). This school of thought believes that there are no benefits received from going farther than the 20 miles – physiological, physical or helping a runner develop 'running economy'. Any longer distance can actually hurt the runner when it comes time to run the marathon.
The second school, usually Galloway followers, believes in actually running the distance of the marathon three weeks before the marathon, and up to 28-30 miles if the runner wants to run the marathon with a time goal, say trying to qualify for Boston or breaking a 3, 4 or 5 hour time goal. They believe that once the 'wall' [which usually shows up between Mile 18 to 21] is broken in practice, it won't show up at the marathon. Since the runner knows for sure that he/she can go the distance, they have a mental and physical advantage in completing the marathon.
So, which school of thought is right?
Well, actually, it's both. Let me explain.
I've trained for marathons using both methods. The first has a runner running those 20 milers at or near the speed of the time splits at which they will run the marathon. Let's take the runner trying to break 4 hours in the marathon. He or she will try to do their 20 miler in 3 to 3-1/2 hours. This projects out to 9-9:30 minutes per mile. If they need a 9:09 MPM, this is a good test.
If you follow the Galloway guidelines, yes, you will be running a 28-30 miler three weeks before the marathon. But for a 4 hour marathon goal, he will have you run that in 5 to 5-1/2 hours, at 11 minutes a mile, clearly 2 minutes slower than what you should be able to run that on race day. By running it 2 minutes slower, it will help you recover faster so that in three weeks, you will not only know you can run the marathon distance, but also have recovered from the long 30 miler.
So, when you look at both concepts, they are correct. The 20 miler theory 'programs' your body and stride length to know what it's like to run at a set predictable pace. The Galloway method teaches your body to burn fat as a primary source of fuel, teaching it how to access that fuel and 'expect' a longer distance than what you will do at the marathon.
By now you're wondering 'So why are you choosing to run a marathon distance as a training run'? The answer lies in how my training is going. I've already run a 22 miler at a 9:30 MPM pace. So I know that I should be able to keep that pace for the marathon. But I'm not sure that my body has been accessing fat as a primary fuel during my run. I noticed the last two to three miles of that 22 miler, my minutes per mile started creeping up. So I want to teach my body to go to my fat reserves for fuel, hence, incorporating the Galloway theory. So, I will be forcing myself to run the Stillwater Marathon at a pace two minutes slower than I know I'm capable of.
But I'll be honest, training for the marathon is a crap shoot, it's not like any other distance. Lots of theory and practice go into trying to find the "Marathon Holy Grail". In a month, I will be able to tell you whether I found it or not.