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Let’s begin with a thought experiment.
You’ve trained for months. Your legs are ready. Your lungs are primed. But what happens if you start the Quebec Mega Trail—say, the 50 km, the 100 km, or even the 135 km—on an empty tank?
Not much. Because while your muscles may be willing, they’re entirely dependent on a much more fragile system: your fuel.
And here’s the thing: ultra-distance success isn’t just about physical preparation. It’s about biochemistry. It’s about how much fuel your gut can process, when your muscles start running out of glycogen, and why your brain might decide you’re done even when your legs still have miles to go.
That’s where fueling comes in. And that’s where we come in.
PART 1: Weeks Before — Train Your Gut, Not Just Your Legs
Let’s start with a truth that surprises a lot of athletes: your gut is trainable. Just like your quads, your core, and your VO₂max, your gastrointestinal system adapts to training.
But here’s the catch: it only adapts if you challenge it.
Why Gut Training Works
In long events, we’re not limited by what we burn, but by what we can absorb. Your muscles may want 90g of carbs per hour, but if your gut can only handle 40g? That fuel becomes useless—or worse, a source of bloating, cramping, and nausea.
Studies show that with consistent practice, athletes can increase carbohydrate absorption by over 50%. That means more energy reaching your muscles, and fewer GI issues shutting your day down early.
How to Train Your Gut
- Start with 30–40g carbs per hour during your long runs
- Build toward 70–100g/hour over 3–4 weeks
- Simulate race-day conditions: similar effort, terrain, and duration
- Use the fuel you’ll actually race with—XACT ENERGY and ENDURANCE Bars are ideal because they’re consistent, predictable, and tested in real-world events
Your race-day stomach isn’t a mystery box. It’s a system. Train it.
PART 2: Days Before — Carb Load, Plan, and Prepare
The Carbohydrate Calculator
The Surprisingly Simple Tool That Solves One of Endurance Sports’ Most Misunderstood Problems
Let’s ask a deceptively basic question:
How much energy do you burn when you run for hours?
The answer, it turns out, depends not just on how long you run, but on how hard you’re going.
That’s the principle behind the XACT Carbohydrate Calculator. It takes two things:
- Duration of your effort
- Intensity (relative to your personal effort level)
And from those two variables, it estimates something incredibly important:
Your hourly rate of carbohydrate usage—aka how quickly you're burning through glycogen.
Why That Matters
You start a long race with about 90–120 minutes of stored glycogen. After that, you need to supply carbs externally to maintain performance. Burn rate increases with effort, and the calculator does the math to tell you how much fuel to bring in per hour.
It gives you:
- Your target carb intake/hour
- Your total carb target for the race
- A suggested mix of ENERGY and ENDURANCE Bars
- A framework to test your plan in training
Most runners who try it learn one thing fast: they’ve been under-fuelling.
And once you see the numbers, you can plan with intention—not guesswork.
Smart Carb Loading: Not Just “More Pasta”
So you’ve built your fueling plan, but the plan will only work if you start with a full tank! This is where carb loading comes into the picture. You may have heard of it - but what does it actually do?
Your body stores carbohydrates as glycogen in your muscles and liver. And when you run long distances, glycogen is your primary fuel. If you start empty, you finish early.
But carb loading isn’t just “eating a lot.” It’s strategic. It starts 2–3 days before your race.
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Center Every Meal Around Carbs
Shift your plate. Every meal should be mostly carbohydrate—pasta, rice, potatoes, bread, fruit, oatmeal. Keep proteins and fats light. Don’t aim to feel stuffed; aim to feel constantly topped up.
Example food day:
- Breakfast: Oatmeal + banana + honey
- Lunch: Rice bowl, easy on the protein
- Dinner: Pasta with bread
- Snacks: Fruit bars, pretzels, juice, crackers
-
Hydrate Intentionally
Glycogen binds water. Carb loading only works if you hydrate properly. Sip throughout the day. Use XACT ELECTROLYTE Tabs to boost absorption and maintain balance.
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Avoid Food Experiments
No new foods. No salads. No high-fiber “health” snacks. You want foods that are familiar and easy to digest.
Your body performs best when it’s not confused.
Race Morning Fuel
Eat your final pre-race meal 3–4 hours before start time. It should be mostly carbs, low fiber, and already tested in training.
Example:
- Toast with jam
- A banana or ENERGY bar
- 500–750ml of water with electrolytes
- Coffee (if you usually drink it)
This meal is about stability, not fullness. It’s your last quiet moment to fuel before the action begins.
PART 3: Race Day — Where Execution Equals Outcome
This is where it all comes together.
1. Start Fueling Early—Because Your Gut Is Ready
Here’s something not enough people know: your gut is most receptive in the first hour. Blood flow is high. Digestion is efficient. But as race intensity increases and fatigue builds, digestion slows dramatically.
So eat before that happens.
Start fueling within 20–30 minutes of the start. Not because you feel hungry—but because this is your window of opportunity. Begin with 30–40% of your first three hours of carbs early, while your gut is saying “yes.”
Don’t wait for a problem to solve. Stay ahead.
2. Beat Palate Fatigue with Flavour Rotation
Eating the same thing over and over triggers “sensory-specific satiety.” In plain terms: even your favourite bar starts tasting like cardboard after six hours.
Use variety as a tool.
- Rotate ENERGY bar flavours every 30–60 minutes
- Start with ENDURANCE bars early in the day for real-food texture
- Save your favourite bar for the darkest moment of the race
Your fueling strategy isn’t just physiological—it’s psychological.
As we explored in this article, taste plays a psychological role in endurance, motivation, and even perceived effort.
3. Separate Carbs and Fluids for Maximum Control
When you combine fuel and fluids into a single drink, you lock yourself into one ratio. But conditions change. Sweat increases. Your stomach fills. Now what?
We keep it flexible:
- Fuel = ENERGY and ENDURANCE bars
- Hydration = Water + ELECTROLYTE Tabs (1 per 500ml)
More heat? Add tabs. Too full? Ease off fluids, keep eating
Separation gives you precision. And precision wins races.
4. Caffeine: Used Intelligently, It Works
Caffeine reduces perceived effort and boosts endurance. But only when it’s used well.
- Preload with 50–100mg about 30–60 minutes before the start
- Re-dose every 3–4 hours if you’ve practiced it
- Don’t wait until you’re tired—use it to stay sharp
Peak caffeine effect takes about an hour. Plan ahead, and let your brain stay in the game while your body works.
5. Fuel Before Climbs and During Recovery Sections
High effort = low digestion. Steep hills, heat, altitude—all reduce blood flow to the gut.
Eat before you climb. Use descents and flats to fuel. Chew while you can. Let your gut work when your legs aren’t redlining.
Even spacing and timing are more important than total intake. Set a timer. Write your plan on your bottle. Execute like it matters—because it does.
Final Summary: Six Rules to Fuel By
| Principle | Action |
|---|---|
| Start early | Eat in the first 30 minutes, even if you don’t feel hungry |
| Gut training | Build to 90g/hour with ENERGY and ENDURANCE bars |
| Smart carb loading | Center meals on carbs, hydrate, skip fiber |
| Fuel variety | Rotate flavours and textures to avoid burnout |
| Separate carbs and fluids | Independent control = smarter adaptation |
| Caffeine strategy | Use to stay sharp, not just wake up |
Your Fueling Strategy Is a Performance Tool
Fueling isn’t an accessory—it’s a performance system.
It’s science-backed, athlete-tested, and ultimately the difference between surviving and performing.
At XACT, we build fueling that helps you go farther, faster, and with fewer GI issues—because we believe that food should feel like a help, not a burden.
You've done the training. Now do the fueling.
Let XACT Nutrition power your best trail day yet.