I wanted to run 12 miles today. I didn’t manage to get that far, I was just…tired feeling. Then I read this interesting post about energy and running, and that got me thinking.
The most interesting part was the section on energy (the rest of the post is certainly great as well, for other reasons):
Rule of thumb you burn 100 calories per mile. i.e. marathon = 2,600 calories. (For comparison I eat a little under 1,800 calories/day.) So this is mathematically not possible: your carrying capacity is max 2,000 calories glycogen, another couple hundred contributed by burning fat. Still 400 calories to find.
How do you close the gap?
- Train and get biomechanically more efficient at moving
- Train and get better at storing and converting glycogen (up to that 2,000 calories level)
- Train while fasting to improve fat burning
- Carb load: you can temporarily store more glycogen than usual, so load up with carbs 48 hours before a race
- Eat on the way: running gels contribute 80 calories each of glucose into your blood, and that slows glycogen conversion. I had four gels on the way round. They take about 30 minutes apiece to hit your system.
I did the above while training for my first marathon (reassuring) and I think what did it for me today wasn’t anything to do with my energy stores, it was more that I a) was going too fast (I probably should have been 9-9:30 a mile instead of 8:38) and b) I didn’t get enough sleep the night before after running 7+ miles.
Sometimes the answer isn’t that complicated.
But still, I want to see if I can run 200 miles in a month in May, which means I’ll be doing a 10-mile run five days in a row for 4 weeks straight. This might require some more strategy on the energy/hydration front than I’m used to. ᕙ(⇀‸↼‶)ᕗ
Comments welcome!