MARATHON FUELING STRATEGY FOR A 4-HOUR FINISH

How to nutritionally approach a 4-hour marathon

Last year, I had the opportunity to write an article for Crown Sport Nutrition about how to prepare nutritionally for a 3-hour marathon. This year, the focus shifts to those aiming to complete the marathon in 4 hours. If this is your goal, I encourage you to reread the previous article, as it also provides valuable recommendations for runners targeting the 4-hour challenge.

As sports Dietitians–Nutritionists, we often focus on the fastest or most visible athletes. However, if we take a broader perspective, who are the athletes we can truly help the most?

The profiles of those aiming to finish a 4-hour marathon are diverse: some are first-timers, others see it as a personal challenge, or even as a “celebration” without wanting to suffer too much. Still, most share two main concerns:

– Avoid physical issues during training.
– Prevent gastrointestinal problems on race day.

Regardless of level, every runner looking to complete a marathon in 4 hours must:

1. Ensure adequate rest between training sessions.
2. Follow an individualized nutritional strategy adapted to their lifestyle and training load.
3. Train the digestive system with clear goals based on fitness level and race pace.

In consultations, we often observe that many runners follow predefined training plans based on target finish time, which can imply very different effort levels for each athlete. For one runner, a given workout might feel like 6/10 effort, while for another, the same session could feel like 9/10.

Dietitians–Nutritionists must interpret these differences and adjust nutrition and fueling strategies based on each athlete’s demands. This is essential for designing an optimal fueling plan for marathon day.

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Fueling strategies for a 4-hour marathon

We will propose two fueling scenarios based on effort level:

1. Runners with high cardiovascular and metabolic demand, who push themselves significantly at their race pace.
2. Runners whose priority is maintaining steady pace, where mechanical demand (impact and muscle fatigue) is higher than metabolic load.

In both cases, two days before the race, it is recommended to reinforce hydration by drinking 1 liter per day of a hypotonic drink, prepared by diluting one sachet of Crown Sport Nutrition’s Isodrink in 1 liter of water.

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First proposal: Fueling plan for high cardiovascular and metabolic demand

In this strategy, runners who push within their race pace require a nutritional approach suited to their metabolism. It is important to remember that although they train, rest, and eat well, not all athletes metabolize energy in the same way.

To illustrate this, think of cars. While all vehicles need fuel and oil, there is a big difference in consumption between a regular car and a race car. The same applies here: more demanding runners have higher energy needs, but as a general rule, they will not need more than 60 g of carbohydrates per hour. However, some individuals may require more depending on their characteristics.

Fueling plan

Before the start — warm-up (15–20 min prior):
• 1 Energy Gum Bar

Carbohydrate distribution: 240 g total

Hydration plan: 80 g CHO

– Prepare 500 ml of water with 3 scoops of Isodrink.
– 500 ml of isotonic drink every 2 hours of racing (total: 1 liter).
– Depending on temperature and humidity, drink small sips of water from aid stations.

Intake plan: 160 g CHO

• 45 min → 7.9 km → 45 g CHO
• 1h 15 min → 15.8 km → Energy Gel (25 g CHO)
• 2h → 21.1 km → Energy Gum Bar (22 g CHO)
• 2h 45 min → 29 km → HyperGel 45 (45 g CHO)
• 3h 30 min → 34 km → Energy Gum Bar or Energy Gel (22–25 g CHO)

Caffeine may be introduced using caffeinated product options or caffeine capsules, depending on tolerance and adaptation.

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Second proposal: Lower cardiovascular and metabolic demand

Depending on the athlete and their digestive training, it may be appropriate to choose a more demanding fueling strategy (as in the first proposal) or to follow a more conservative plan of around 45 g of carbohydrates per hour.

Choosing a conservative fueling plan is justified by the “lower” carbohydrate oxidation rate when running at an easier pace and, as mentioned earlier, because many of these runners approach the event in a more recreational way.

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Fueling plan for 45 g of carbohydrates per hour

Before the start — warm-up (15–20 min prior):
• 1 Energy Gum Bar

Carbohydrate distribution: 180 g total

Hydration plan: 80 g CHO

– Prepare 500 ml of water with 3 scoops of Isodrink.
– 500 ml of isotonic drink every 2 hours (total: 1 liter).
– Drink small sips of water at aid stations depending on temperature and humidity.

Intake plan: 100 g CHO

• 50 min → 8.8 km → Energy Gum Bar (22 g CHO)
• 1h 40 min → 17.5 km → Energy Gel (25 g CHO)
• 2h 30 min → 26.4 km → Energy Gum Bar (22 g CHO)
• 3h 20 min → 35.2 km → Energy Gel (25 g CHO)

Caffeine may be introduced using caffeinated product options or caffeine capsules, depending on tolerance and adaptation.