The human body has a limit to its endurance, and scientists have been studying what factors set these limits. A recent study published in Science Advances found that the long-term performance limit for both elite athletes and pregnant women is 2.5 times their normal basal metabolic rate. The researchers believe that the gut is responsible for this limit, as it can only effectively convert a limited amount of food into energy.
To investigate this limit, scientists followed six ultra-endurance athletes who completed the 4,800-kilometer Race Across America on foot. They found that during the first stages of the competition, the athletes consumed multiple times their normal basal metabolic rate. However, their energy consumption decreased each day until it reached a constant upper limit, which was the maximum 2.5 times their normal basal metabolic rate. The researchers concluded that the body automatically regulates metabolism to reach a level that can be sustained long-term.
The study also found that the same limit applies to pregnant women, as their energy consumption during pregnancy was nearly the same as that of the ultra-endurance athletes. The researchers attribute this to the digestive process, as the gut can only process a limited amount of food each day, which limits the amount of energy that can be provided. Further studies will explore whether elite athletes can exceed this limit under certain conditions and what factors are crucial in determining the performance limit.
