The key to human endurance, the ultimate limit of energy use, has been determined by US researchers by analyzing a 4828 kilometer run, the Tour de France bike race and other prestigious sports events.
Researchers at the American Duke University have shown that the peak of the so-called resting metabolism of the average human body is two and a half times or 4,000 calories per day, and energy consumption cannot be sustained in the long run.
It has also been found that pregnant women are champions of endurance as their metabolism is close to the tolerance of the human body, the BBC wrote.
The research began with a running race across the United States, with a total of 4828 kilometers in 140 days to reach California, the capital of California. For six months, six marathon distances (42.2 kilometers) were run, while scientists investigated how their organizations responded.
Before and during the race, their resting metabolism was measured, that is, how many calories they burn when they rest. They also measured how many calories they used during extreme endurance competitions.
They started competing with high energy consumption, which eventually reached a 2.5-fold level of resting metabolism, according to the authors of the study published in the current issue of Science Advances.
Only one marathon runner used 15.6 times their resting metabolism. During the three days of the Tour de France 23, cyclists competed for 4.9 times their resting metabolism, and 3.5 times their 95-day antarctic cycling.
“The extraordinary intensity is going on for a few days, but if we want to continue running or cycling, we have to take it back,” says Herman Pontzer, a research participant, at the BBC.
The energy consumption of pregnant women reaches 2.2 times the resting metabolism, that is, it is near extreme athletes.
Scientists say the 2.5-fold use of resting metabolism does not depend on the performance of the heart, lungs or muscles, but rather on the performance of the human digestive system.
It has been found that the body cannot digest, absorb, and process enough calories and nutrients to maintain longer energy consumption.
On shorter distances, the body can burn, and during rest, you can rebuild your own fat or muscle mass. In extreme-time races, however, on the edge of exhaustion, energy consumption must be balanced – scientists wrote.
According to Pontzer, the results can also help athletes to select their wisdom wisely.