Children always seem to have bags of energy and never run out of steam. Researchers found that children have the stamina and levels of recovery of endurance athletes. Children recover from "high-intensity exercise" a lot quicker than athletes. A study looked at the performance levels of children cycling, and compared their fitness to athletes. Dr Sebastien Ratel said: "We found the children used more of their aerobic metabolism and were therefore less tired during the high-intensity physical activities. They also recovered very quickly – even faster than the well-trained adult endurance athletes."

The researchers hope their findings will help scientists understand how the human body changes with age. It could help in the fight against diabetes and other diseases. Dr Ratel warned that children are becoming less active. He said: "With the rise in diseases related to physical inactivity, it is helpful to understand the physiological changes with growth that might contribute to the risk of disease." He said children should keep fit as they grow up and play a lot so they become healthy adults. He said: "Children seem to have the ability to play and play…long after adults have become tired."