It seems that a lot of you were shocked by the statement that my mileage base was too small for anything over a 10K. When I found this out, I was shocked too. But, let me see if I can clarify things a bit.
I want to begin by saying that my weekly mileage base is too small to be COMPETITIVE in any distance over a 10k. But it is NOT too small to FINISH longer distances. And there is a distinction in that. Some people see this as COMPETING VS. COMPLETING. And I would like to throw out there that to be "competitive" does not mean that you are in the mix to place, but rather that you be "competitive" versus your past performances and in comparison to your times in other distances. Make sense?
Let's use me as an example. I have a 5K PR of 24:09 and I run 25-30 miles a week. My base is large enough to be competitive at the 5K. If you calculate what I should be running a half marathon in based on my 5K time, I would have a half PR around 1:51. But what is my half PR? 2:01:36.
OK, so let's reverse that calculation. If you calculate what my 5K PR should be based on my current half PR, you come up with a time of 26:07 - a two-minute difference. Reversing the calculation like that shows that I have an adequate base for shorter races, but not necessarily so for longer races. Long story short, it comes down to endurance. I don't have the endurance to hold a comparable pace at a half marathon that I can at a 5K. And how do you build your endurance? YOU LOG MORE MILES. It's as simple as that.
And in case you were wondering (and I know you were), I am looking to build my base to 35-45 miles per week in order to COMPETE in distances up to a half marathon. This same base would allow me to FINISH up to a 30K.