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How to Fuel for Peak Performance: Mastering Race Nutrition for Ultramarathons

Race nutrition stands as a pivotal factor in the success of ultramarathon runners. Inadequate nutrition strategies often lead to underperformance or hitting the dreaded "wall" or "bonk," characterised by a sudden onset of fatigue and a significant drop in pace. However, the repercussions extend beyond mere pace reduction; poor nutrition planning can result in cramps, sickness, heightened risk of injury, and more severe complications. As a rule of thumb, the longer the race, the higher the calorie consumption required, whereas shorter races demand less calorie intake. In this article, I provide useful information that can help your nutrition strategy during competition for optimal performance.

1. Balancing Macronutrients for Endurance

These guidelines primarily cater to ultrarunning but can be adapted to suit other ultraendurance sports like cycling races, Ironman, and Ultraman. A balanced approach is key, combining carbohydrates (CHO), proteins, and fats to optimise performance. In events spanning over 4-6 hours, the recommended energy intake comprises approximately 50-65% from CHO, 20-35% from fat, and 15-20% from protein, targeting a total of 250 calories per hour. Notably, CHOs serve as the primary energy source due to the utilisation of muscle glycogen storage and circulating glucose during exercise.

2. Enhancing Carbohydrate Utilisation

CHO oxidation primarily occurs in the intestinal wall, facilitated by various transporters. Glucose is rapidly absorbed at a rate of about 60 grams per hour via the sodium-dependent transporter (SGLT1), providing quick energy. Meanwhile, fructose, another type of carbohydrate, is absorbed at a slower rate of approximately 30 grams per hour through the glucose transporter 5 (GLUT5). These two constitute the main carbohydrates utilised. Complex CHOs, such as maltodextrin commonly found in sports gels, release energy slower due to their intricate structure and bind to the glucose transporter SGLT1.

3. Optimal Carbohydrate Intake for Long-Distance Events

For races shorter than a marathon, the advised carbohydrate intake is around 60g per hour, and for these carbohydrates that target only SGLT1 is sufficient. However, for events exceeding 4 hours, consuming 90 grams per hour of multiple transportable carbohydrates in a 2:1 ratio of glucose to fructose is recommended. This strategy enhances gastric emptying and optimises carbohydrate utilisation during exercise, overcoming the saturation of SGLT1 with high glucose (or similar) consumption. Moreover, studies have shown that this ratio improves performance and reduces perceived effort (RPE) compared to when taking glucose alone [1]. In fact, mixing fructose:glucose/maltodextrin further enhances this, ensuring CHO absorption and oxidation, translating to constant energy for the muscles that can be utilised for power and endurance [2, 3]. Incorporating this approach during training is imperative to mitigate gastrointestinal discomfort.


When it comes to gels, Maurten stands out as my preferred choice due to its clean composition and effectiveness. Products like Maurten Gel 100 or Maurten Gel 160 (here, the caffeinated version), containing the 2:1 glucose-fructose ratio, or Maurten 160 or 320 with maltodextrin, offer sustained energy without artificial flavours or colourants.

4. Protein's Role in Ultraendurance Events

Including protein during ultraendurance events can aid in reducing muscle damage and maintaining protein balance. Studies suggest a protein intake of 0.25 grams per kilogram per hour, alongside 90 grams per hour of carbohydrates, to enhance performance. This can be achieved through specialised sports nutrition products or real food options (my choice!) such as peanut or almond butter sandwiches or hummus wraps. Moreover, intake of a combination of CHO and protein after the event has increased recovery rates [4].

5. Replenishing Electrolytes for Prolonged Endurance

Electrolyte replenishment becomes crucial during prolonged endurance activities, especially after three hours of sweating. Most sports drinks contain sodium chloride and potassium chloride to address electrolyte loss. The balance between sodium and potassium is pivotal in preventing cramps, emphasising the need to monitor sweat loss and adjust electrolyte intake accordingly. Generally, males lose more sodium than females, emphasising the importance of this in men.

6. Conclusions

Mastering race nutrition is not only about fuelling the body but also about optimising performance and mitigating risks. Personalised nutrition strategies to individual needs, experience and preferences, and adequate hydration and electrolyte management can significantly enhance the ultramarathon experience.




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