Nutrition tips for the half marathon

Half Marathon Nutrition Guide: Optimizing Performance and Recovery

Preparing for a half marathon represents a unique challenge in the journey of a distance runner. Positioned at the intersection between the sustained intensity of short-distance races and the pure endurance of the marathon, this event demands a level of physiological and nutritional discipline that is often underestimated.

If physical training builds the engine, nutrition provides the essential fuel needed to prevent premature depletion of glycogen stores, a phenomenon that frequently occurs around the fifteenth kilometer. Meticulous dietary management not only helps maintain a stable target pace, but also prevents gastrointestinal and muscular problems that can compromise performance.

An analysis of best practices and current data highlights that nutrition should be approached as an integral part of preparation, beginning several weeks before the start and continuing well beyond the finish line.

The physiology of exertion over 21.1 km

To understand the importance of a nutrition strategy, it is necessary to analyze the energy mechanisms involved during a half marathon. At a running intensity close to the anaerobic threshold, the body prioritizes carbohydrate oxidation as its main energy source. The human body has limited glucose stores, primarily stored as glycogen in the liver and skeletal muscles.

Glycogen and blood glucose dynamics

The total glycogen stores of a trained adult amount to approximately 500 g, representing around 2,000 calories. During intense exercise lasting more than an hour, these reserves inevitably become depleted if no external fuel is provided. A drop in glycogen levels leads to a reduced capacity for muscle contraction and central nervous system fatigue. The fueling strategy therefore has two objectives: saturating glycogen stores before the start through carbohydrate loading and maintaining blood glucose levels during the race to spare muscle glycogen for as long as possible.

Preparation: building a solid nutritional foundation

Performance nutrition is not limited to the final days before competition. From the beginning of the training plan, often six to eight weeks before the event, nutrition should support the workload and promote cellular recovery.

Macronutrient balance and micronutrition

A balanced diet is based on a regular daily intake of protein for repairing muscle fibers damaged by repeated impacts, starchy foods for daily energy replenishment, and quality fats for hormonal and anti-inflammatory health. Consuming fruit and vegetables, at least five servings a day, provides the vitamins and minerals essential for energy metabolism.

Hydration should be considered a lifestyle habit. A state of chronic dehydration, even if mild, increases blood viscosity and places additional stress on the heart during every workout. The aim is to have clear urine throughout the day, indicating a balanced fluid balance.

Digestive system training, or Gut Training

The digestive system undergoes major stress during running: reduced blood flow to the stomach and intestines in favor of the muscles, mechanical impact, and thermal stress. It is essential to practice "Gut Training," which involves consuming gels, bars, or energy drinks during long runs. This process accustoms the stomach and intestines to absorbing nutrients during exercise, thereby reducing the risk of nausea or diarrhea on race day.

The week before the race: the loading strategy

The seven days leading up to the half-marathon are crucial for turning the body into an optimal energy reserve. This period is divided into two distinct phases.

From D-7 to D-4: stabilization and transition

During this phase, training decreases in intensity and volume (tapering). Nutrition remains normal but balanced, taking care not to consume excess unnecessary calories despite the reduction in activity. However, start favoring lean meats and limiting overly spicy foods or saturated fats that could make digestion more difficult.

From J-3 to J-1: “Carb loading” or carbohydrate loading

The goal is to radically increase carbohydrate intake to achieve maximum glycogen saturation. Recommendations range from 8 to 12 g of carbohydrates per kilogram of body weight per day. To reach these levels without digestive discomfort, it is advisable to choose low- or moderate-glycemic-index carbohydrates such as white rice, al dente pasta, or sweet potatoes, while drastically reducing fiber (raw vegetables, whole grains), which speeds up transit undesirably.

Maltodextrin is particularly relevant here. This glucose polymer increases carbohydrate loading without excessive sweetness or the satiety of a huge pasta meal. By consuming 30 to 60 g diluted in water several times a day, the runner optimizes their reserves smoothly and efficiently.

Race morning: the start protocol

The pre-race meal is often a source of anxiety. Its main purpose is to replenish liver glycogen after the overnight fast and maintain stable blood sugar without causing stomach heaviness.

The ideal breakfast and timing

Ideally, this meal should be finished 3 hours before the start to allow complete gastric emptying. It should be rich in easily digestible carbohydrates and low in fat, fiber, and complex proteins. Classic options include white bread with honey or jam, a ripe banana, or an energy cake.

Coffee can be beneficial for concentration and fat mobilization, but its consumption should be moderate because of its diuretic properties and its potential to irritate the stomach in some individuals. Between the end of breakfast and the start, a small amount of water or a very lightly sweetened drink can be consumed in small sips to maintain hydration without overloading the bladder.

Half-marathon fueling strategy

A 21.1-kilometer race requires actively managing intake to compensate for the loss of mineral salts caused by sweating and glucose consumption. Consistency is key: waiting until you feel thirsty or tired means that the deficit has already set in, and it is already too late.

Hydration: beyond plain water

Water alone is not enough during prolonged exercise lasting more than 1 hour 30 minutes. Sweating causes a massive loss of electrolytes (sodium, potassium, magnesium). Drinking only large quantities of water can cause hyponatremia, that is, a dangerous dilution of mineral salts in the blood. It is therefore recommended to consume 150 to 250ml of fluid every 15 to 20 minutes.

Using an isotonic drink is recommended. Its carbohydrate content (between 4% and 8%) and electrolytes enable rapid intestinal absorption and effective cell rehydration. For more details on this topic, it is strongly recommended that you consult the guide on marathon hydration, which details the ideal mineral ratios for endurance sports.

Energy intake: gels and fruit purées

The standard recommendation for a half marathon is an intake of 30 to 60g of carbohydrates per hour. This amount may vary depending on the runner’s weight and the intensity of the effort.

• Energy gels: They provide a high concentration of sugar in a small volume. Mulebar favors a natural approach, using brown rice syrup for a rapid supply of glucose and agave syrup for a more gradual supply of natural fructose (glycemic index of 15). This combination prevents blood sugar levels from fluctuating and avoids sudden drops in performance. Mulebar’s energy gels are also the only ones that are truly resealable, allowing you to consume them in 3 or 4 servings—this makes all the difference. It is essential to drink water after taking a gel to rinse your mouth, dilute the sugar in your stomach, and speed up its passage into the bloodstream. To choose the right product, the article on which energy gels for the marathon provides an in-depth comparative analysis of the different textures and flavors.

• Energy compotes: For those who find gels too sickening or too sweet, energy compotes offer a slightly thicker, fruity texture. They are particularly easy to digest and provide a more natural feeling of satiety without weighing on the stomach. Their resealable packaging with a cap also allows them to be consumed in several portions to avoid too sudden an intake of sugar.

• Energy bars: Although more common in longer events such as trail races, small bites of bars can be consumed at the beginning of the race if the expected duration is more than two hours. It is still difficult to chew while running.

How much to consume during a half marathon

 

The importance of minerals and electrolytes in performance

Endurance performance is inseparable from mineral balance. Electrolytes are not mere additives, but catalysts for biochemical reactions.

• Sodium: This is the mineral lost most through sweat. It maintains the plasma's osmotic pressure and helps prevent hyponatremia.

• Potassium: Essential for transmitting nerve impulses and muscle contraction. A deficiency is a common cause of early fatigue.

• Magnesium: It plays a key role in ATP production (energy) and promotes muscle relaxation, thereby limiting the occurrence of painful cramps.

• Calcium and zinc: Although lost in smaller quantities, they contribute to bone strength and protein metabolism during prolonged exercise.

Mulebar products incorporate these mineral salts in balanced amounts into their drinks and gels, often using ingredients naturally rich in these nutrients rather than synthetic additives.

Recovery: tomorrow's training starts now

Once the finish line has been crossed, the body is in a state of significant oxidative stress, with low energy reserves and partially damaged muscle fibers. Nutritional recovery should revolve around three main principles, often summarized as the "3 Rs": Rehydrate, Refuel, Repair.

The metabolic window

This is the approximately 30- to 60-minute period after exercise when glucose transporters and protein synthesis mechanisms are highly activated. Taking advantage of this metabolic window can considerably speed up the return to normal (homeostasis).

1. Rehydrate: Drink water rich in bicarbonates and sodium to replenish losses and neutralize the acidity produced by intense exercise.

2. Refuel: Consume fast-acting carbohydrates (fruit, compote, juice) to immediately restart glycogen resynthesis.

3. Repair: Consume approximately 20g of high-quality protein (eggs, plant-based proteins, dairy products) to stop catabolism and repair muscle micro-tears.

A specific recovery drink combining carbohydrates and protein in a 3:1 or 4:1 ratio is the most practical tool for meeting these needs immediately after the race.

The Mulebar approach: natural ingredients and environmental responsibility

In a market saturated with ultra-processed sports nutrition products, Mulebar stands out with a philosophy focused on ingredient quality and environmental responsibility.

100% natural ingredients for easy digestion

Mulebar gels and bars contain no preservatives, colorants, or artificial flavors. The energy base consists of natural cereal syrups (brown rice) and agave, providing a smooth texture and authentic taste that does not overwhelm the palate during intense exercise. This natural formulation is the best protection against the stomach problems frequently caused by synthetic products. It is also worth emphasizing that all the recipes are formulated to create delicious products that lift your spirits during intense effort.

Innovation and practicality: resealable tubes and eco refills

A major Mulebar innovation lies in its resealable, reusable gel tubes. Unlike conventional sachets, which must be consumed all at once and soil pockets, flip-top caps allow runners to take their gel in several small sips, smoothing sugar intake and avoiding insulin spikes.

In addition, Mulebar offers 444g eco refills, equivalent to 12 gels. This system allows runners to refill their own containers (reusable tubes, silicone flasks, or soft flasks), providing a solution that is 33% cheaper than individual gels while considerably reducing plastic waste on trails and roads.

Original and invigorating flavors

The brand offers gel recipes that are out of the ordinary, such as lemon-ginger (excellent for digestion), coffee (for a final boost), and salted caramel (for sodium intake). This variety allows runners to adapt their tastes throughout training and competitions, avoiding flavor fatigue.

Successfully completing a half marathon requires a 360-degree approach in which what’s on your plate and in your bottle matters just as much as your running shoes. By understanding glycogen mechanisms, adopting a rigorous carbohydrate-loading strategy, and managing fueling with natural, tested products, runners can transform a potentially painful event into a controlled performance experience.

Nutrition should never be a source of uncertainty on race day. It should be the foundation supporting your mindset as you cross the finish line with the satisfaction of a job well done. By incorporating the advice in this guide and exploring the sustainable solutions proposed, every athlete gives themselves the means to achieve their ambitions, whether it is their first race or a new personal record.

 

Answers to frequently asked questions

What is the exact distance of a half-marathon?

A half-marathon measures exactly 21.0975 kilometers, precisely half the distance of an official marathon (42.195 km).

Is it difficult to run a half-marathon?

The difficulty depends on your training level and target time. It is an accessible distance for any regular runner who can run 10 km without stopping, but it requires 8 to 12 weeks of specific preparation to complete comfortably and without injury. 

What is the average time for a half-marathon?

For an amateur runner, the average time is generally between 1h50 and 2h10. Experienced runners often aim for the symbolic 1h30 mark, while the world record is approaching 57 minutes.

What should you eat 3 days before a half-marathon?

Begin carbohydrate loading. Opt for "white" starches (rice, pasta, steamed potatoes) and reduce insoluble fiber to avoid bloating. Hydration should be increased by 500 ml per day compared with your usual intake.

Should maltodextrin be taken?

Maltodextrin is recommended to saturate glycogen stores without overloading the stomach. It is particularly useful during the final two days before the race, diluted in drinking water throughout the day.

How many gels should be consumed during the race?

The classic strategy for a half-marathon is to take two to three gels. One around the 7-kilometer mark, a second around the 14-kilometer mark, and possibly a final "kick" at the 18-kilometer mark.

How can digestive problems be avoided while running?

The main mistake is trying a new product on race day. Test every gel and drink during training, avoid fats and fiber the day before, and drink enough water with every serving of solid or semi-liquid food.

What is the best diet after a half-marathon?

Prioritize rehydration and glycogen replenishment. A snack combining carbohydrates and protein (e.g., a banana and yogurt, or a recovery drink) should be consumed within 30 minutes of finishing.