February 15, 2020
One of my biggest fears in approaching a new round of marathon training is the energy aspect. My understanding of the body, in simplistic terms, is that at any given time we’ve all got a fairly robust reserve of metabolically-ready energy in our cells and blood. There is a ton I could say about how energy is stored and converted to different forms in the body, but this is not a medical text, and I’m a little rusty. But let’s vastly oversimplify this and say that at any given time the average weekend warrior probably has ready access to anywhere between 90 minutes to 3 hours worth of active, ready fuel in their blood. This differs from stored fats and metabolizing protein and is much more complex than just blood sugar, but round about it’s what folks are folksily referring to when they reference The Wall: the point at which the active body energy battery icon turns red.
I’m usually sitting around 2+ hours, depending on what I ate last, when I ate last, and how good my training plan was leading up to, say, a race.
Two hours is perfect for a half marathon. Eat a good meal. Hydrate. Run. Drain the battery as you approach or cross the finish line. Boom! Race complete, and no need to charge on course.
Two hours is shit for a marathon. My marathon time is a bit more than double that on a good race.
So I gotta fuel.
For simplicity sake, I use the estimate that in an hour of running I burn net 600 calories. I’m sure there are better calculations, but let’s keep this basic. For safety, this means I need — need, so that I don’t collapse of energy bonking on the course — 3,000 calories on hand and ready to burn. Assuming that I start with that ready two-hour bank of, say, 1,200 calories inside me, I need to consume 1,800 calories over the course of the race to meet that metabolic need and not bonk out. That’s a lot of food.
That’s ten litres of Gatorade or soda.
That’s two fast-food lunches.
That’s half a kilo of candy.
That’s almost too much to carry.
But being a calorie sherpa is not my biggest woe. My problem is that eating while running has often had the effect of making my nauseated, unbalanced, and generally ready to barf-bag it on course. The big hurdle, the big challenge of a marathon, then becomes how the hell to consume two meals worth of calories over five hours while running 42 klicks. Ten litres of electrolytes is too much to carry and too unreliable at aid stations. Too many gummy chews would make me sick even without the run. Gels are high-energy, low-weight but I’ve had mixed success with them (and the texture alone is a killer!)
My quest for the next 8 months is to either (or both) find a food category that doesn’t make me wobble and train myself to be snacking while on pace. And I’m not even sure how to start either of those journeys.
* I’ve got a dusty twenty-year-old biology degree under my belt but don’t take this as any kind of nutrition advice.