Have you ever exercised until you were exhausted, then wondered if it was your limit? In the world, there are still superheroes like Dean Karnazes, a man who can run continuously for 3 days and 3 nights without sleep. Do you think you can’t compare your limits with someone like Karnazes?
A new study published in Science Advances shows that it turns out, we all have a similar limit in endurance and endurance. That’s when the body burns calories at a rate of 2.5 times the rate of metabolism when resting.
This limit is independent of your level of exercise and physical activity. That is, no matter who you are, what you’re doing, a morning man or a pregnant woman is in labor pain, as long as the calories burn at 2.5 times the rate of metabolism when you take a break. We all reached the threshold of the body.
To find the limits of the human body, a group of researchers analyzed data from a variety of endurance challenges and various life events – from a 4,957 km long ultramarathon cross-shore competition in The United States, until the energy needs of pregnant women.
“This will help determine the realm of what is possible for people,” evolutionist anthropologist Herman Pontzer from Duke University in North Carolina said.
Part of the new study involves tracking the energy spending of six competitors in the Trans-American Race: a five-month-long run, in which athletes have to complete six races. each week with a total distance of more than 4,800 km.
A hard limit at 2.5 times the metabolic rate in a resting state.
The researchers also looked at previously published data of the Tour de France, Arctic expeditions and many other similar events.
The results of the study show that marathon athletes consume 15.6 times more energy when resting. The figure is 4.9 times in professional cyclists, 3.5 times in Arctic explorers and 2.2 times for a normal pregnant woman.
But the L-shaped curve graphs show a hard limit at 2.5 times the rate of metabolism in a resting state. Reaching that threshold, there was a slowdown in the process of harnessing the energy of the body. It starts to return to eating itself, especially fatty tissue to get energy.
That explains why marathon athletes can run through the United States with a metabolic rate of 15.6 times the rest state. But they will have to “reset” their body every day by resting, not running continuously.
Below the threshold of 2.5, when women use only 2.2 times their metabolic rate, they have not reached the limit, so they can be pregnant for 9 months without exhaustion.
“You can do things that put stress on your body for a few days, but if you want to get longer, you have to go back to your own body,” Dr. Herman Pontzer said.
A review of colleagues’ research, evolutionary biologist Daniel Lieberman from Harvard University, said: “Those are very good data, proving very convincingly that human endurance has a hard limit “.
This limit seems to have been built into our bodies, where people really need to reduce the rate of calorie burning to maintain equilibrium. We cannot use energy faster than we can replenish our bodies.
Scientists propose to call this milestone a biochemical point caused by the digestive system: at some point, our bodies cannot process food into fuel faster than we burn. them.
Research shows that athletes can burn calories more than absorbed in a short time. But in the long run, our bodies finally have to break that process by a brake of 2.5x.
For marathon runners, their energy expenditure has stalled after 20 days. They could resist nature to run hard for the first 20 days, but the brakes on 2.5x appeared on the 21st day.
Therefore, research is especially meaningful for them, athletes who practice for events that require high durability. Knowing the limits can help them plan how to best play below this 2.5x ceiling.
Science has found the limit of human endurance, overcoming it, the body will have to feed itself to function.
However, researchers do not rule out the possibility that some “superheroes” might be able to break this limited release of energy.
“I guess that is a challenge for elite endurance athletes,” Dr. Pontzer said. “Science will have to reconsider when you prove it wrong. Maybe someone will pass this ceiling someday, and show us we made a mistake at some point.”
Source: Sciencealert, Science, BBC