Planning the marathon when the half marathon test race is done.

by Hege Saltnes

Marathon time based on your half marathon :

"Hi Marius.
I am using your program for my second year. Last year I achieved my goal finishing Paris marathon in 3.57.
Last weekend I ran the Half marathon test race and finished in 1.43.44. I was very surprised :-) as I beat my future best with 7 minutes!
Meaning my goal has to be adjusted for London marathon in four weeks. Using your time calculator I shall be aiming for 3.48. Using the MyPaceCalculator I shall be aiming for 3.38. Can you explain this difference? And give an advice?
Kind regards Hege, Sandefjord, Norway"

Answer: Hi Hege and thanks for your question plus congrats on your half marathon time.

The reasons why my calculator is somewhat conservative is that most of the other calculators do not take into account two things :

1) The difference between the fastest runners (sub 2: 45-2:30) and the "main" pack of runners - 4:00 and upwards. For the faster runners, it is easier to calculate the marathon time based on the half - due to a number of factors such as usually longer running experience, shorter total duration in minutes and generally less "weak" links vs. the more inexperienced runners.

Therefore, you want to be a little bit careful leading up to the half.

2) I'm a big fan of "negative splitting". Most of these calculators go for even-running, while I like to keep the opening up for going faster towards the end. So by predicting the finishing time a little bit slower, you can allow yourself to push hard at the 25-30k if you feel like it and get very close to your ideal time. On the other hand, if you do not have the day - you will not "blow up" because the half-marathon passing time is more on the safe side.

In either day I wish you all the best with your training and race !

kind regards,

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