Coach Chris explains the science behind bonking and outlines practical strategies on the Find Your Edge podcast to prevent it during long-distance triathlon, running or cycling events. Bonking is preventable with a little planning, strategy and science.

If you’ve ever felt like your legs turned to concrete and your energy tanked mid-race… you’ve likely bonked. 😵‍💫

Bonking is the endurance athlete’s worst nightmare—and it’s completely preventable with the right fueling strategy.

What Is Bonking, Really?

Bonking = glycogen depletion—aka running out of your muscles’ stored carbs.
Once those fuel stores are empty, your body says: “Nope. Not today.” 😩

Here’s what you’re working with:

• ~400–600g of glycogen stored in your muscles (that’s ~1600–3600 calories)

• ~60–90g in your liver

Even the fittest athletes can burn through these during long, intense efforts—like marathons, half Ironmans, or long training days.

The Symptoms Go Beyond Just Feeling “Tired”

If you’ve bonked, you know it’s more than fatigue:

• Dizziness

• Shakiness

• Confusion

• Extreme exhaustion

Ever seen a pro crawl across the finish line? That’s real glycogen depletion.

Fuel Your Fire: Carbs Are Your Best Friend

During endurance events, carbohydrates are king 👑. While training can improve your glycogen storage, you still need to top off the tank during activity.

Here’s the general rule:

• 30–60g of carbs per hour for most athletes

• Some can train up to 90–120g/hour with the right carb combos

Why Carb Combinations Matter

Your body can only absorb ~1g/min of glucose… unless you bring in a second player: fructose.
Using both allows your body to absorb and use more fuel thanks to different intestinal transporters.

Look for products with blends like:

• Glucose + fructose

• Maltodextrin + sucrose + fructose

But don’t just grab any product—test what works for you.

Train Your Gut Like You Train Your Body

Fueling only works if your gut can handle it.
That’s why we say: practice your fueling plan in training. Start small and increase gradually. Your gut is smart—it adapts!

And yes, flavor matters. If you won’t eat it on race day, it’s not part of your plan.

Environmental Factors? They Matter More Than You Think

Hot day? 🥵 You’re at a disadvantage. Heat can drop your carb oxidation by 10%—because blood shifts to your skin to keep you cool, not to your gut to help with digestion.

Race-day nerves? 😬 They can mess with digestion too.

This is why you need a personalized plan—not just a generic fueling chart.

Final Word: No Surprises on Race Day

Create a fueling plan that accounts for:

• Your sweat rate and electrolyte losses

• Your exercise intensity

• Your event demands

• Environmental conditions

Test it. Tweak it. Trust it: Never try something new on race day—it’s not worth the gamble.