I'm sorry but I'm with Stevie See here.
Of course those calculators make it crystal clear with your hypothetical marathon time. However, in the real world ... Do a bit of power of 10 stalking .....and you will see that it is just hypothetical. Very few manage to demonstrate the balance. And like Stevie says. When you finally nail that MP marathon after 6 months training your 10k/10mile will have come down thus giving you a new and faster MP.
There`s a degree of confusion here.
A pace calculator (such as McMillan`s) gives you a rough guide to pace equivalence over a variety of distances.
At/near the start of the marathon training process, input a recent race time. This will provide an indicator of marathon potential 12-16 weeks down the line.
The calculator is not a cast iron predictor of paces at all distances but it does provide a useful tool.
Using Stevie`s figs (see above), McMillan predicts 2`52`49; Riegel (a different equation) predicts 2`51`26; Cameron comes out at 2`54`54; Daniels & Gilbert`s VO2 max predicts 2`52`08. In other words, there is near universal agreement that he is capable of running low 2`50`s.
`Hypothetical` perhaps - but entirely realistic provided he does the required training (and it makes no difference whether you`re elite , or not).
Now say, Stevie decides that 2`52 +/- is a bit ambitious/aggressive. He`s got a few injury issues/busy months at work and therefore can`t do the required training. He decides, instead, to aim for a 2`59`59 marathon.
To achieve this time on race day he must run at about 6`53/mile.
THAT will be his m.p. (or goal m.p., if you prefer).
He should (according to most coaches) spend a certain amount of time training at m.p. ie. running at 6`53/mile. If he doesn`t, he will find it much harder to find and hold that pace on race day.
Furthermore, goal m.p. also impacts on the pace at which he should train, i.e. on the pace that he should run: (i) long runs (ii) tempo [lactate threshold] runs and (iii) rep sessions (iv) recovery runs; and, of course, (v) marathon pace runs.
That is why McMillan`s calculator is so useful. It`s principal utility lies not in predicting a marathon time but in allowing you to input your goal m.p. [by time] and in so doing, derive appropriate training paces.
Thus, if Stevie were to input 3`00 for his marathon, the calculator recommends tempo runs @ 6`15 - 6`31/mi; long runs @ 7`23 - 8`23/mi; recovery runs @ 8`23 - 8`53/mi etc.
These figures are obviously not absolutely inflexible but again, they do provide useful guidance and how to structure one`s training.
Apologies to Stevie for using him as my guinea pig
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Edited: 31/08/2011 at 15:20