Why Kids Always Have Energy: Their Muscles Recover In The Same Way As Endurance Athletes

Are you surprised? Thought not.

Ever wondered why kids run around all day and never seem to get tired? You’re probably not surprised to hear that a new study has found kids basically have the same energy levels as endurance athletes (so that’s why it’s virtually impossible to keep up!). 

Researchers discovered young children are able to run around all day because their muscles resist fatigue and recover in the same way as elite endurance athletes. The study, published in Frontiers in Physiology, asked young boys, untrained men and endurance athletes to do high intensity exercise and looked at how quickly they grew tired. 

“We found the children used more of their aerobic metabolism and were therefore less tired during the high-intensity physical activities,” said Sebastien Ratel, associate professor in exercise physiology who completed this study at the Université Clermont Auvergne. “They also recovered very quickly - even faster than the well-trained adult endurance athletes - as demonstrated by their faster heart-rate recovery and ability to remove blood lactate.” 

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Kids recovered more quickly than endurance athletes during the high intensity task.

Professor Ratel added: “This may explain why children seem to have the ability to play and play and play, long after adults have become tired.”

In the study, researchers compared the energy levels of 12 boys aged between eight to 12, 12 untrained men and 13 male endurance athletes. They were asked initially to do two, seven-second sprints, followed by one minute recovery. Next, they were asked to cycle as fast as they could for 30 seconds. 

Each group was assessed for the body’s two different ways of producing energy; 1) Aerobic - uses oxygen from the blood - and 2) Anaerobic - doesn’t use oxygen and produces acidosis and lactate which may cause muscle fatigue. The participants’ heart-rate, oxygen levels and lactate-removal rates were checked after the cycling tasks to see how quickly they recovered.

In all tests, the children outperformed the untrained adults. In recovery, they outperformed the endurance athletes. During the cycle, the adult’s power fell by 51.8%, and athletes by 41.8%, but children’s only decreased by 35.2%. 

Professor of health science at the University of South Australia, Tim Olds, said the study was interesting, but said it didn’t mean kids were, in general, as fit as endurance athletes. “What it’s found is the way they recover more resembles endurance athletes, than untrained adults,” he said, according to ABC News