Amy Stephens
MS, RDN, CSSD, CEDS
Licensed dietitian
specializing in sports nutrition
and eating disorders
How to avoid hitting the wall during a marathon
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By Amy Stephens RDN CSSD
Sports Nutritionist NYC - Kate Cochran, Nutrition Intern
If you’ve trained for a marathon, you’ve probably heard about ‘hitting the wall.’ It’s what happens when your body runs out of stored energy, and suddenly the effort feels twice as hard. any athletes describe it as legs feeling heavy like cement and having no energy. Maintaining the same pace or speed feels more difficult, forcing the body to slow down. It typically occurs in endurance events such as marathons but can happen in any sport. Hitting the wall doesn’t just reflect your fitness level; it has to do with exercise expenditure, glycogen stores and overall fueling. Hitting the wall is not inevitable. With the right fueling and pacing plan, energy levels can remain steady for the duration of your competition, and even provide a kick at the end.
Whether you’re an experienced runner or running your first marathon, these key strategies can help you avoid hitting the wall.
Key points:
- Train your gut to tolerate carbs during long runs
- Top off glycogen: Eat a carb-rich dinner the night before your race
- Start race morning with a carb-rich breakfast
- During the race: fuel early and often (that includes fluids and electrolytes)
- Don’t go out too fast: Follow recommended paces
Throughout your training cycle
Train your gut:
While many runners understand the necessity of fueling during the marathon, what most still don’t realize is that successful marathon fueling actually begins during the training cycle. Training the gut refers to the practice of taking in fuel on the training runs. Over time, the body adapts by upregulating enzymes that help convert sugar (gels) into usable energy.
- Practice taking in carbs in the form of gels and/or sports drinks during long training runs. Your body has to learn how to digest and fuel efficiently on race day.
- Aim for 30–60 g of carbs per hour – that’s about 1-2 gels per hour (approximately 8 gels for a 4 hour marathon). Some runners can handle up to 90 g/hr.
- Tolerating carbohydrates will preserve muscle glycogen longer, allowing you to maintain faster paces. During a training cycle, the gut will adapt to gels and sports products by converting sugar into a usable fuel source.
- Practice with different kinds of gels, chews, sports drinks, or a combination until you find what works for you. Then stick to it and keep practicing. If you struggle to get enough fuel due to palate fatigue, practice alternating fuel types or flavors to ensure you are able to keep putting it in your body.
- Eat the same pre-race breakfast that you plan to eat on race day before long runs. Like with gels, once you find what works, stick to it.
Race week – carbohydrate loading
Carbohydrate loading maximizes muscle and liver glycogen stores, giving your body quick, efficient fuel on race day. Full glycogen stores help delay fatigue and reduce the risk of ‘hitting the wall’.
- In the days before the race, prioritize consistent, high-quality sleep. This is when your body does the bulk of its recovery work — repairing muscles, balancing hormones, and storing glycogen in your muscles and liver. Sleep helps your body use fuel effectively to repair muscles, balance hormones and top up glycogen stores. Ensuring proper, even extra, sleep during the carb load phase pre-marathon will help your body use the extra fuel and set you up for race day success.
- Keep your meals balanced with lean proteins and healthy fats, but let carbs take up half of your plate.
- Choose carb-rich foods you’re comfortable digesting: pasta, rice, potatoes, oatmeal, bread, fruit, and simple snacks like pretzels or graham crackers.
- Spread carbs throughout the day rather than overloading in one sitting — this helps with absorption and prevents stomach discomfort.
- Check where aid stations are (before the race) and plan which ones you’ll use for water, sports drink, or backup fuel. Note which gels will be offered on the course – New York and Chicago Marathons provide Maurten gels on the course.
- In the week before, gradually add more carbs to your typical meals. There is no need to overeat beyond fullness, which can leave you feeling bloated and uncomfortable. This will leave you feeling bloated and uncomfortable. The goal is to consume enough carbohydrates to top off glycogen stores.
- 3-7 days before the competition, carbs make up 50% of your plate.
- 2 days before, carbs make up 60% of your plate. Aim for 7–10 grams of carbohydrate per kilogram of body weight per day. For context, most endurance athletes typically eat around 5–7 grams of carbohydrate per kilogram of body weight per day during regular training so this amount is a significant increase. For example, a 60 kg (132 lb) runner would target 420–600 grams of carbs per day in that window.
- The day before, carbs make up 75% of your plate. Here’s an example of a dinner the night before: pasta, grilled chicken, and a small salad.
Race day:
3–4 hours before the start
If pre-race nerves suppress your appetite, remember that your body needs fuel to perform, and a high carbohydrate pre-race breakfast will help you in the last 10k of your race.
- Have a carb-rich breakfast.
- Aim for 2-4 grams of carbohydrate per kilogram of body weight; that is about 200-300 grams for a 150 pound person (e.g., a bagel with jam and a banana, and a sports drink).
- Stick to what you’ve practiced.
- Keep fat, protein, and fiber low to reduce risk of GI distress.
- If you’re feeling nervous, write out your plan to ensure you consume enough food. This will remove nutrition from the equation so you can focus on other things.
- Stay hydrated: aim for 20–30 oz of fluids at this time. Even mild dehydration forces your body to work harder, depleting energy as it tries to stay cool and keep muscles firing.
30–60 minutes before the start
- Optional top-up of ~25 g carbs (gel, banana, or 5 oz sports drink).
During the race:
- Fuel early and often. Start fueling within the first 30–45 minutes and keep a steady intake throughout. Don’t wait until you feel tired; fuel ahead of it.
- A general rule of thumb is to take in fuel about every 30 minutes during the race. Setting a timer on your watch is a great way to remember when it’s time to fuel.
- Race day is not the time to try a new gel flavor, energy chew, or sports drink. Stick to what you’ve practiced.
Hydration & Electrolytes:
In addition to carbohydrates, your body also requires fluids and electrolytes. Together they help the body absorb the necessary nutrients and keep the muscles firing. At later stages of the race, it might be harder to hydrate and you might feel the end is close, but it’s important to continue to hydrate.
- Sip fluids regularly and include electrolytes (sports drink or salt tabs) to replace what you lose in sweat.
- Rather than gulping fluids which can lead to GI distress, sip throughout your race to allow time for your body to absorb.
- Certain gels like Maurten, Science in Sport (SIS), and UCan contain extra fluid so no need to take extra with these products.
- Use whatever works best for you — grab fluids at aid stations, carry a handheld bottle, wear a hydration pack, or have friends hand you bottles along the course.
