“An ultramarathon isn't about running. It's about making yourself keep moving forward when every cell in your body is screaming: ‘Enough!’”

— Scott Jurek, ultrarunning legend, winner of the Western States 100 (7 times in a row)

So, you've decided to run an ultramarathon. Congratulations! You have officially joined the club of people who believe that 42.2 kilometers is just a decent warm-up. Your friends may be tapping their temples, and your relatives are probably already stocking up on sedatives. That's perfectly normal.

The first and most important thing to understand: an ultramarathon is not just “a marathon, only longer.” It is a completely different sport, with different rules and — most importantly — with completely different demands on your body. The mindset of “I've run a marathon, so I'll just keep running longer” is a straight road to disappointment, suffering and, most likely, an inglorious DNF somewhere in the woods at three in the morning.

Imagine that your body is a hybrid car. It runs on two types of “fuel”:

Carbohydrates (glycogen). This is our “electric” motor. Powerful, quick, great for sharp accelerations. But there's a problem: the “battery” is tiny. It lasts for 1.5–2 hours of intense work. When it runs out, you hit what marathoners call “the wall” — your legs suddenly turn to jelly, your head spins, and all you want to do is lie down and stop moving. Sound familiar?
Fats. This is our “gasoline” engine. It's not as powerful and won't let you go very fast, but the “fuel tank” is practically bottomless. Even the leanest athlete carries enough fat reserves to run from London to Edinburgh. Not bad, right?

Bottom line: the goal of ultra preparation is to teach your body to efficiently use its enormous “gas tank” of fat while sparing the small carbohydrate “battery.”

So a marathoner is a racer trying to squeeze the maximum out of the “electric battery,” constantly topping it up at aid stations. An ultramarathoner is a wise traveler who knows the road is long and that most of the distance must be covered on the “gasoline” engine, saving the “electricity” for steep climbs and the finishing kick.

The Marathon Wall? On an Ultra It's Just the First Bump

If on a marathon “the wall” means the finish is near, on an ultramarathon it's only the beginning of the real adventure. The glycogen stores in our muscles and liver amount to roughly 2000 kcal. That's barely enough for 30–35 km of running. So what do you do when you still have 50, 70 or 100 kilometers ahead of you?

The answer is simple: you need to teach your body to become a “fat-burning machine.” The goal of ultra preparation is not just to train your legs, but to rebuild your entire energy supply system. To make it use the practically endless fat reserves as efficiently as possible at a low heart rate, and to save the precious carbohydrates for real emergencies.

The Six Pillars of Ultra Success

To become such an efficient “hybrid car,” we will need to work on six key parameters. Don't be scared by the intimidating terms — in the following chapters we'll break each of them down in plain language:

VO2max — the “size of your engine.” It shows how much oxygen you can process. The bigger it is, the higher your potential.
VLamax — the “battery drain rate.” It shows how quickly you burn carbohydrates. For an ultramarathoner, the lower this number, the better.
FatMax — the “efficiency of the gasoline engine.” It shows how well you burn fat. This is our trump card.
Thresholds (LT1, LT2) — the “warning lights on the dashboard.” They help you understand at what speed you switch from “gasoline” to “electricity.”
Running economy — the “fuel consumption per 100 km.” How much energy you spend on every kilometer of the journey.
Strength endurance — the “durability of the suspension.” The ability of your muscles to withstand hours of load, especially on descents and climbs.

In the next chapter we'll look “under the hood” of the body and examine these markers in more detail. Buckle up — it's going to be interesting!