The study found the physical limits of endurance sports

WASHINGTON, June 6 (Xinhua) -- An international team of researchers has found that people exercise for long periods of time with an unsurring energy limit, and that athletes end up burning calories at levels about 2.5 times their metabolic rate.
study was published recently in the American journal Science Advances. The researchers studied a group of athletes who ran six marathons a week for five months in 2015. Daily data show that they start with high levels of energy consumption, but soon decline and remain at about 2.5 times the underlying metabolic rate for the remaining mileage.
basic metabolic rate refers to the minimum energy metabolic rate that a person's body needs to consume to sustain life in a calm state at natural temperatures.
show that even the best endurance racer can't break that limit in the end. The researchers believe this suggests that the body self-regulates after a period of high levels of energy consumption.
reason for the limits of endurance exercise is the body's limited ability to digest food and absorb calories, the researchers said.
study found that all endurance sports, whether dragging a sled in the cold winter or cycling in the summer, were in line with this pattern, unlike previous studies of the ability to regulate the temperature of the endurance association table.