Ultramarathons: Can We Overcome Them Physiologically?

Ultramarathons, races that exceed the traditional marathon distance of 26.2 miles or 42 kilometers, are the epitome of pure-endurance sports. These grueling events, often ranging from 50 to 100 miles or more, subject the human body to extraordinary challenges. Understanding the physiological changes that occur during an ultramarathon is crucial for athletes aiming to tackle these extreme distances. Here, we will explore what happens to the body during an ultramarathon and how to address the physiological changes.

Part 1: Energy Depletion

During an ultramarathon, the body relies heavily on stored glycogen for energy. As the race progresses, glycogen storage in the liver is depleted, leading to a phenomenon known as hitting “the wall.” To prevent this, ultramarathoners must adopt effective fueling strategies. Consuming easily digestible carbohydrates, electrolytes, and fluids at regular intervals helps sustain energy levels. Most commonly used are caffeinated gels for shorter ultramarathons, but many include “real” food in their nutrition plans for longer ultramarathons. Training the body to utilize fats efficiently through a well-balanced diet and long training runs can also be beneficial.

Part 2: Muscle Fatigue

Ultramarathon distances put immense stress on your muscles, leading to fatigue and microtrauma. This microtrauma occurs due to the repetitive motion of running, leading to tiny tears in muscle fibers. To minimize muscle fatigue, adequate training, including strength and flexibility exercises, is essential. Stretching and foam rolling during breaks in the race can alleviate muscle tightness and reduce the risk of injuries.

Part 3: Hydration and Electrolytes

Maintaining proper hydration and electrolyte balance is critical in preventing dehydration and electrolyte imbalances, which can lead to cramps, nausea, and dizziness. Regularly sipping water and electrolyte-rich beverages is essential, especially for races in hot and humid conditions such as the Pyrenees Stage Runs in Spain or the Moab 240 in Utah. It gets as simple as monitoring your urine color as a method to gauge hydration status – clear or light yellow urine indicates adequate hydration.

Part 4: Temperature Homeostasis

Ultramarathoners often face extreme weather conditions, ranging from the scorching heat of Death Valley to the cold rain of the Barkley Marathons. The body’s ability to regulate its temperature is challenged during such races. To prevent overheating, wearing moisture-wicking clothing and a hat, as well as applying sunscreen, can help. In cold weather, layering clothing and wearing gloves and a hat are crucial to retain body heat. It’s also vital to listen to your body and adjust your pace and clothing accordingly.

Part 5: GI Issues

Gastrointestinal problems, such as nausea, bloating, and diarrhea, are common challenges faced by ultramarathoners. These issues can be triggered by a variety of factors, including improper nutrition, dehydration, and the physical, constant movement of internal organs during the race. To address these problems, experiment with different foods and hydration strategies during your training runs to identify what works best for your body. Additionally, practicing mindful eating and avoiding overly spicy or fatty foods before the race can help prevent GI distress.

By recognizing the challenges and employing appropriate strategies – including training, nutrition, hydration, and mental preparation – athletes can conquer these extraordinary distances and achieve their ultramarathon goals. Each ultramarathon is a unique journey, and learning from each experience is key to continuous improvement and success in this demanding sport.


Image is of the Knee-Knacker Ultramarathon on the Baden-Powell Centennial Trail from https://www.runguides.com/event/559/knee-knacker.

1. https://marathonhandbook.com/ultramarathon-nutrition/

2. https://thegoodstuffco.com/blogs/monthly-blend/jeff-pelletier-freedom

3. https://www.outsideonline.com/running/racing/race-fuel/the-latest-best-and-most-scientific-hydration-strategies-for-runners/

4. https://pubmed.ncbi.nlm.nih.gov/25716739/


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