Hale/ZUMA Wire/Alamy Live News Psychological stresses Winner Scott Harber completed the annual Weymouth Woods 100km ultramarathon, in North Carolina, in 10 hours, 39 minutes and 55 seconds.

Scholars don’t know if these are good or bad. The scientific jury is still out as to how ultramarathons affect the heart in the long term, as structural changes to the heart after extended training and competing in ultramarathons have been noted. This damage is generally reversed within a few days. Elsewhere, runners can also experience tissue damage to, among other things, the heart, the kidneys, the muscles and the joints.

The sleep deprivation involved in longer races impairs physical and cognitive performance, and often leads to hallucinations. Symptoms vary from nausea, vomiting and headaches to altered mental states, seizures and death. These low levels of sodium in the blood have been found to cause hyponatremia in up to 51% of participants in single-stage ultramarathons, compared to up to 28% for standard marathons. This can cause digestion problems and discomfort. Imagine trying to replace 2.8 litres of fluid an hour while running. Some runners, depending on the environment, will lose up to 2.8 litres of sweat per hour, which results in a loss of salts too. If participants aren’t able to meet their calorific demands through food, they can end up in considerable energy deficit, with the body using its own muscle mass and fat as fuel. This type of distance alone puts immense stress on the body. The Marathon des Sables in the Sahara and the Last Desert in Antarctica each cover 250km.

Athletes often compete in extreme conditions. Godong / Alamy Stock Photo Physical stressesĪn ultramarathon is a race that exceeds the 42.2km distance of traditional marathons. The Ultra-Trail du Mont-Blanc is an annual single-stage mountain race in the French Alps.

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