Why Half-Marathon Fuelling is Your Secret Weapon

By Rachel Turner | Nutritionist & Run Coach

Hi, I’m Rachel. I’ve been running for over 15 years, covering everything from the track to ultra-marathons. If there is one thing I’ve learned, it’s that running a half-marathon is harder than people give it credit for.

13.1 miles is a long way to go, and yet, fuelling is often the last thing on a runner’s mind. We spend weeks training our legs, but we forget that our bodies do not have an infinite energy source.

If you’ve ever hit Mile 10 and felt your legs turn to lead and your brain starts screaming at you to stop then this is hitting the wall. It’s not lack of training or mental toughness, it’s a fuelling problem. And it’s a problem that can be prevented so you can finish your race feeling strong, rather than crawling over the finish line.

The Half-Marathon “Intensity Trap”

To understand why we fade, we have to look at the science of our “fuel tanks.” Think of yourself as having a Fat Tank and a Carb Tank.

They don’t work in isolation; they run simultaneously. The Fat Tank provides a slow drip of energy, while the Carb Tank (your glycogen stores) cranks up to provide the power needed for higher intensities. When we run a half-marathon, we aren’t just jogging; most of us are working at around 80% of our VO2 Max. At that level, your body is burning far more carbohydrates than fat. It’s important to note here that this is relative, so you can be running slower than someone else but actually working at a higher intensity because it is based on your personal VO2 max. So no you are not ‘too slow’ to need to consider fuelling.

Here is the “Math Problem”: Most of us only store enough glycogen to last for roughly 90 to 120 minutes of running—and that’s only if your tanks are 100% full when you start. If you’re planning to be out on the course for longer than 90 minutes, your tank will likely hit empty before the finish line unless you have a strategy to keep it topped up.

Why “Winging It” Usually Fails

I know what many of you are thinking: “But Rachel, gels cause stomach issues!” I hear this all the time. But here is the truth: Your gut is a muscle, just like your legs. You wouldn’t show up to Northstowe without having trained your cardiovascular system, so why would you show up without training your GI system?

When we run, blood flow is diverted away from the gut to the muscles that need it most—your heart, lungs, and legs. Digestion slows down, which is why people get “gut rot” or nausea. However, by training the Gut, you teach your body to handle fuel even when blood flow is low.

GI issues usually come down to three avoidable mistakes:

1. Not practising with your fuel in training.
2. Not taking enough water with your carbs (your gut needs fluid to process that energy!).
3. Eating too much fibre in the lead-up to the race.

The Performance Gap: Finishing vs. Racing

We’ve all seen the images of runners collapsing across the finish line. That happens because they’ve given 110% and their glycogen stores are completely depleted. They’ve run out of “high-octane” fuel and are trying to finish on that “slow-drip” fat energy alone.

It doesn’t have to be that way. You can have a sprint finish and cross that line feeling strong. Proper fuelling also changes the “Monday Morning” experience. Part of the reason people struggle to walk down the stairs for three days after a race is that they didn’t give their body the energy it needed post-race to kickstart recovery.

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Join the Northstowe Nutrition Webinar

I want to show you exactly how to fix these problems so you can have your best race day yet. I’m hosting a free webinar specifically for Northstowe runners where we will break down the exact protocols you need:

• The Carb-Loading Strategy: Welcome to the “Beige Era.” We’ll look at how to fill your tank without the bloat.
• Training the Gut: How to teach your system to digest those gels while you’re moving.
• The Carb-per-Hour Ratio: Exactly how much you need to be aiming for.
• Caffeine: How to use it to your advantage (or why you might want to avoid it).

Replay link will be sent out, so sign up even if you can’t attend live.

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About Rachel