What to eat before a marathon: what does science say and how to use it in practice?

Nutrition is undoubtedly as important an aspect of race preparation as training itself, but unfortunately many athletes often neglect it. But in a marathon, good or bad nutrition can make the difference between finishing the race in your dream time or, in the worst case, not finishing at all.

Athletes who don't perform as well as they expected in a race often blame their failure on nutrition: they ran out of energy, were dehydrated, or had digestive problems. Very often, it's because athletes consume too much energy and fluids, or too little.

Another common mistake is trying new products that athletes have not tested in training. In this article, we will provide you with the basic knowledge needed for a successful nutritional strategy and to complete the marathon in your dream time without any difficulties.

In the article you will learn

• Why nutrition is key to a successful marathon
• The role of carbohydrates and the importance of their supplementation
• What is carb-loading?
• How to have a proper breakfast on race day
• What to eat and drink just before the start
• Nutrition and hydration during the race
• The importance of caffeine for performance
• How to prevent dehydration and indigestion
• Why train and have a nutrition strategy

Why is nutrition so important for a marathon?

Marathon times range from 2 to 6 hours, depending on physical condition. The current record for men is held by Kelvin Kiptum at 2:00:35 and for women by Tigist Assefa at 2:11:53. Energy expenditure during these 42.195 km ranges between 2200 and 3200 kcal, with body weight being the main factor. Interestingly, energy expenditure over this distance is almost unrelated to pace! There is a simple reason for this. A runner who burns half the calories per minute as a faster runner will run for that much longer – and the resulting energy expenditure will be very similar.

What problems can you encounter during a marathon?

Poor nutrition can lead to hypoglycemia (low blood sugar), and the runner will then barely make it to the finish line, weak and with heavy legs. Even if low blood sugar does not manifest itself immediately, the supply of energy to the muscles may be insufficient, which will negatively affect performance.

In warm conditions, dehydration can also occur – fatigue, headache and confusion are common consequences.

And the third common problem is digestive problems. We often see runners vomiting on the side of the course or rushing to the portable toilets - such is the reality of the marathon for runners who do not pay enough attention to their marathon nutrition.

How can you avoid these problems and increase your chances of a great race?

In addition to being well-trained and rested, four key nutritional factors affect marathon performance:

1. Sufficient energy reserves to complete a marathon:

   • enough muscle glycogen

   • sufficient liver glycogen

   • continuous carbohydrate replenishment during the race

2. Proper hydration
   Prevent dehydration during the race, but also avoid excessive fluid intake. This is especially crucial in hot weather.

3. Minimizing the risk of digestive problems
   Some runners are lucky and avoid these problems, but most struggle with them to some extent, so their nutrition needs to be well-tested and adjusted.

4. Dietary supplements – in moderation
   Outside of sports nutrition, energy gels, drinks, and bars, caffeine will have the greatest acute effect on performance, so we will discuss it further in the article.

Carbohydrates as fuel for performance

The body uses two main sources for fuel: carbohydrates and fats.

• Fats are the primary source of energy during low to moderate intensity, or aerobic, phases.
• Carbohydrates, on the other hand, are more important at medium to high intensity, as they can provide energy to the body much faster.

For this reason, carbohydrates are the main source of energy during exercise, while fats find their main application during longer distances at low intensity.

The body has reserves of both fuels, but the carbohydrate reserve is significantly smaller than the fat reserve. Even the leanest athlete has enough fat reserves to handle the longest races at low intensity. In contrast, the carbohydrate reserve in the form of glycogen in the muscles is normally 500–800 g and in the liver about 80 g – which is enough for 2–3 hours of intense activity.

Many marathoners are familiar with the term “hitting the wall” – the moment when the body runs out of carbohydrate stores, usually between 28 and 32 km. The body then relies solely on fat, which means that the intensity of the performance cannot be maintained unless you take in more carbohydrates.

But there are a few simple strategies to prevent this moment: start with replenished glycogen stores and regularly replenish energy during the race - with drinks, gels or food.

We also sweat when we run. It is a vital process that helps us regulate our body temperature. Without sweating, we would quickly overheat, much like a car engine would overheat without a cooling system. If fluid loss is too great, it begins to negatively affect the functioning of the body. Cardiovascular strain (for example, heart rate) increases, the ability to regulate temperature deteriorates, and the risk of digestive problems increases.

Therefore, it is important to drink enough to prevent these large losses. Smaller fluid losses are okay and can sometimes even be beneficial.

This means that in the weeks leading up to the marathon and during the race itself, we should ensure three key things:

1. Sufficient energy in the form of muscle glycogen

2. Plenty of energy stored in the liver as liver glycogen

3. Proper hydration levels throughout the race

Carbohydrate supercompensation (carb-loading)

To enter the race with replenished glycogen stores, it is important to increase carbohydrate intake one or more days before the race, ideally in combination with a reduction in training load. This process is known as carbohydrate supercompensation. Be careful, however, it is not about overeating - just replacing some of the protein and fat with a larger amount of carbohydrates. We can recommend suitable foods: pasta, rice, potatoes, pastries. Extreme diets from the 70s are not needed.

Breakfast on race day

Breakfast is essential, the morning after a night out, the body is almost depleted of liver glycogen stores because it used them up during sleep. The liver helps maintain blood sugar levels during the race - breakfast is therefore essential for replenishing it. A good breakfast contains 100-200 g of carbohydrates approximately 3-4 hours before the start.

Athletes prone to digestive issues should avoid foods high in fiber, fat, and protein. Sensitive individuals can try lactose-free dairy products or skip them altogether to be safe.

Suitable sources of carbohydrates on race day

• White rice

• Corn or rice cereal

• White bread, seedless bagels

• Pancakes

• Boiled vegetables (without seeds), boiled potatoes

• Ripe bananas

• Cooked fruit, purees, snacks

• Rice cakes, honey, syrup

• Juices without pulp

Nutrition just before the start

15–30 minutes before the start, it is advisable to replenish liver glycogen stores – it is recommended to take 20–30 g of carbohydrates (80–120 kcal) and 90–180 ml of water. Carbohydrates begin to be absorbed and are mainly used in the first kilometers. Gels or energy candies are popular, but here too: train in advance.

It is ideal to use the pre-workout drink hyve Endurance pro , which contains 30 g of carbohydrates per dose in a glucose to fructose ratio of 2:1. This ratio allows you to take in up to 90 g of carbohydrates per hour. However, do not try to achieve this amount of carbohydrates in the race, you need to train for it a few weeks in advance to avoid digestive problems.

Nutrition during the race

Marathon nutrition requires some planning. It’s important to find out what snacks will be available along the course and create a plan that takes into account what you can grab from the refreshment stations and what you need to carry with you. For longer races, your target carbohydrate intake should be higher than for shorter races. For races lasting more than 2 hours, athletes can benefit from consuming about 60 grams of carbohydrates per hour . But don’t try this approach for the first time until the marathon itself! You should gradually build up to this intake during training. Your digestion will quickly adjust.

What foods and drinks you use to do this is up to you. 60g of carbs per hour can be covered by various combinations of water, sports drinks, gels, gummies, bars, or regular food. In recent years, some elite marathoners have been consuming 90g of carbs per hour or more . There are even reports of runners who have managed up to 120g/h . But such a strategy requires careful preparation, without which it could cause problems . The key is to choose the right types of carbs and practice them repeatedly in training for a few weeks before the race . If you haven't done this, don't try this strategy.

Tips:

• Eat your food before the refreshment station where there is water.

• Drink at least a few sips of water with each gel or bite.

Solid food

Energy bars often contain 30-60g of carbohydrates, but also fat, fibre and protein – which can slow down digestion. Therefore, options with low levels of these ingredients are ideal. Bars help against the feeling of an empty stomach, but they tend to be more difficult to digest during a run. Gels or chewy candies are more suitable for some athletes.

Gels and candies (chews)

Gels: small volumes with a high carbohydrate content (20–25 g), there are also variants with caffeine. Candies: a compromise between a bar and a gel – easy to chew, servings of about 6–10 g.

Carbohydrate drinks

Hypotonic drinks
Hypotonic sports drinks usually have a concentration of 6–7%, i.e. 60–70 g/l. A 600 ml bottle therefore contains approximately 35 g of carbohydrates. In addition, it contains sodium and other electrolytes that help with hydration.

Hypertonic drinks
These drinks are designed to contain significantly more carbohydrates than regular sports drinks. They still provide fluids, but their main purpose is to replenish energy. These drinks are especially useful for longer races, when it is not practical to carry a large volume of fluids with you, but you still need to take in enough carbohydrates. Some of these drinks contain up to 90 grams of carbohydrates in a single 500ml bottle.

Caffeine and performance

Caffeine increases performance – about 3 mg/kg of body weight is recommended, which is 200 mg for a 70kg person. It is absorbed in 30–90 minutes, but also works later during the race. The best timing? This is individual. It is important not to exceed a daily dose of 400 mg.

Overview of caffeine content in common products:

• Gels: 25–50 mg

• hyve 100% Natural caffeine : 50 mg/capsule

• Cola (355 ml): 40–50 mg

• Energy drink (250 ml): 50-100 mg

• Espresso: 80–100 mg

Dehydration

Dehydration is another common cause of fatigue in a race. We regulate our body temperature by sweating – the higher the pace, the more heat and the more sweat. If we lose too much fluid (over 3% of body weight), performance decreases. To prevent this, we recommend the hyve Hydration pro hydration drink, which effectively hydrates the body and replenishes energy during performance. To prevent dehydration, it is important to start the race well hydrated and maintain proper hydration throughout the run.

Hydration strategy:

• Before the race, drink at least 500 ml of fluids approximately 2 hours before the start.

• Monitor the color of your urine – it should be light.

• During the race, drink enough to lose a maximum of 2-3% of your weight.

• For slower runners, it's enough to "drink to your thirst", while faster runners should have a plan.

• At the end of the race, the stomach may have less absorbency - hydrate sufficiently from the very beginning of the race. It is wise to use the first part of the race, when the digestive tract is working without problems, to consume carbohydrates and fluids. Do not drink excessively and use common sense - there is a risk of hyponatremia (dehydration). A slight weight loss (1-2 kg) at the finish is normal.

If you experience bloating or a "full stomach" feeling during the race, slow down slightly and give your body time to process the fluids.

Athletes who want to prepare really well can measure how much they sweat in given conditions during training and adjust their fluid intake accordingly. Weight gain during the race is a clear sign of excessive drinking, which can lead to dangerous dehydration. Remember, proper hydration starts in the days leading up to the race.

Training your nutrition is just as important as your running training itself.

Those who are prepared are not surprised. Nutrition is not trained until the expo day before the race! Start 6-10 weeks in advance. Your preparation should also include “nutrition training”. During easy run, recovery run, interval run training, you can train in a low-carb, high-fat mode, on the contrary, during long long runs, which for many runners are typically on Sunday, simulate the race and train the energy and fluid replenishment plan. It is also advisable to train breakfast itself.

The three most common nutritional mistakes during a marathon

1. To have no plan.
   Going into a marathon thinking, “I’ll drink when I’m thirsty and grab something at the refreshment stand when I need it” is a gamble on uncertainty. It might work, it might not. If you’ve invested dozens of hours of training and planning each run, why shouldn’t you also plan your energy and fluid intake? Doing so will significantly increase your chances of success.
2. Too strict adherence to the plan.
   Some runners have a plan, but they stick to it too tightly. A plan is important, but that doesn't mean it can't be changed. When the weather is warmer than usual, you may need to drink more fluids. If you experience digestive problems, it's okay to temporarily reduce your intake.
3. Trying new things.
   Many runners get excited at the expo the day before the race, buying new gels or drinks and then trying them for the first time in the race. That's a recipe for trouble. Stick to what you've tested in training and what you know works for you. A marathon is not a day for experimentation.

Best tips for the end

• Don't try new products on race day.

• Train with the products you will use at least 6 weeks in advance.

• Listen to your stomach – if liquids are not being absorbed, slow down.

• Start the race hydrated – drink enough even a day or two before the race.

• Plan your breakfast in advance. Don't be surprised by the offer at the hotel.