Inspired by serunner, I have done some research into the question of marathon calories. I’m not sure if there is a definitive answer, but I did find this formula:
Calories burned by exercise = ((METs * 3.5 * weight in kg) / 200) * duration in minutes
I also found the Compendium of Physical Activities, which lists the METs for a vast range of different activities, from which I extracted info on running and walking.
I plugged it all into Excel (twice, because Excel crashed and I hadn’t saved it for ages because I’m a muppet) and the answer is:
Running a fast marathon and lying down for a long time burns pretty much the same number of calories as running a slow marathon and lying down for a shorter period of time. The difference comes when you stop running your marathon and start walking it.
So maggiee, you’re sorted.