Marathon runners train for months to prepare their bodies for the big day. But even seasoned athletes sometimes experience the dreaded moment around mile 20 when their energy suddenly vanishes — a phenomenon known as "hitting the wall."

It's not just about tired legs; it's a complex physiological crash caused by improper fueling. So how can runners stay energized and avoid this dramatic drop in performance?

The answer lies in understanding your body's fuel systems and applying science-based nutrition strategies before, during, and after the race.

What Does "Hitting the Wall" Really Mean?

When runners say they've "hit the wall," they're often describing a sharp, sudden drop in energy, accompanied by mental fog, muscle fatigue, and sometimes even nausea or dizziness. This typically happens around the 30-kilometer (18-20 mile) mark — the point when the body runs out of its preferred fuel: glycogen.

Glycogen is stored carbohydrate in your liver and muscles. It's a fast-burning fuel source, essential for sustained running. But your body only stores enough glycogen to last roughly 90 to 120 minutes at marathon pace. After that, unless you've replenished along the way, your body is forced to rely more on oil— a slower-burning energy source that leads to sluggishness.

According to Dr. Asker Jeukendrup, a renowned Sports Nutrition Scientist and Exercise Physiologist: "Carbohydrates are stored as glycogen in the liver and muscles. These glycogen stores are limited, and during exercise they can become depleted. A marathon is a typical example of an event where glycogen stores can become limiting for performance. When glycogen stores run low, the body is forced to reduce its pace significantly, an phenomenon often referred to as 'hitting the wall.'"

Build a Strong Base: Pre-Race Carb Loading

One of the most effective ways to delay the wall is to start the race with full glycogen stores.

Here's how to do it:

• Start 2–3 days before race day: Increase your intake of carbohydrate-rich foods such as rice, oats, bananas, potatoes, and whole grains.

• Aim for 7–10 grams of carbs per kilogram of body weight per day. For a 70 kg (154 lb) runner, that's roughly 490–700 grams of carbs daily.

• Don't overeat fats or fiber: Too much of these can lead to gastrointestinal issues on race day.

This "carb loading" strategy ensures your muscles are stocked with glycogen when the signal goes off.

The Morning of the Race: Eat Smart

Your pre-race meal should be eaten 2.5 to 3 hours before the race and should include 1–4 grams of carbohydrates per kilogram of body weight.

Example pre-race meals:

• A bowl of oatmeal with banana and honey

• Two slices of toast with jam and a sports drink

• A bagel with peanut butter and a glass of juice

Avoid high-oil or high-protein foods that are slow to digest, and steer clear of anything unfamiliar to avoid surprise stomach issues.

Mid-Race Fueling: Timing Is Everything

Even with proper carb loading, your body still needs fuel during the race to maintain energy levels. The key is starting early and fueling often.

During the race:

• Start fueling around 45 minutes in, and continue every 30–45 minutes

• Consume 30–60 grams of carbohydrates per hour, depending on intensity

• Use energy gels, chews, or sports drinks — whichever your stomach tolerates best

• Always practice race fueling during long training runs, never try something new on race day

For hydration, aim to drink small amounts of water or electrolyte drinks every 15–20 minutes, especially in warm or humid conditions.

Fueling the Brain: Don't Ignore Mental Energy

Interestingly, some research suggests that carbohydrate mouth rinses — swishing a sports drink around your mouth without swallowing — can trick your brain into feeling more energized. This is especially useful in the final stages of the race when the body is running on fumes.

Tip: If your stomach can't handle more gels near the end, try a swish-and-spit technique with a sweet sports drink. It can still give your brain the mental "boost" it needs.

Post-Race Nutrition: Recovery Starts Immediately

After crossing the finish line, your body is in a depleted state. Replenishing glycogen and protein stores quickly helps reduce muscle soreness and speeds recovery.

Within 30–60 minutes post-race:

• Eat a balanced meal or snack with carbohydrates and protein (3:1 ratio is ideal)

• Drink plenty of fluids with electrolytes to rehydrate

• Good options: Chocolate milk, banana with peanut butter, smoothie with protein and fruit

Remember: Recovery nutrition helps prepare your body for future training sessions or races. Don't skip it!

Bonus: Train Your Gut

One underrated strategy for preventing "the wall" is training your stomach to tolerate fuel. Your gut can adapt over time to digest more carbs during running if you consistently practice fueling during training runs.

Try this:

• Use your long runs to mimic race day conditions

• Experiment with gel brands, flavors, and hydration schedules

• Train your body to absorb 60 grams of carbs per hour gradually

This reduces the chance of cramps, nausea, or energy crashes on race day.

Fueling Is a Skill You Can Learn

If you've ever hit the wall in a marathon, you know how brutal it feels. But it's not a mystery — and it's not inevitable. With the right fueling strategy, you can protect your energy, avoid crashing, and finish strong. Every runner's body is different, so take time to test, adjust, and listen to how your body responds.

Have you ever hit the wall during a race or long run? What helped you recover — or what do you wish you'd done differently? Let's talk about it — your experience might help another runner avoid the crash.