This is why kids can run all day without getting tired

One study shows that children are metabolically comparable to well-trained adult endurance athletes and are therefore less fatigued during high intensity exercise than untrained adults. That’s why they can easily drain their parents!

If you ask any parent, they’ll let you know: children are tireless. They can bike all day, run all day, play all day without ever getting tired. How can such a small body have so much energy? Why are not they as tired as adults? A team of researchers from the University of Clermont-Auvergne (France), in collaboration with the French Rowing Federation and the Center for Exercise and Sports Science Research at Edith Cowan University in Joondalup, Australia, published on April 24th, 2018 in the journal Frontiers in Physiology a study that explains the reasons for this apparent immunity to tiredness of our little ones.

To provide an effort, the body must produce energy and it achieves it in two ways. The first, aerobic or oxidative, uses oxygen in the blood to produce energy from the body’s sugars and lipids. This method does not cause muscle fatigue, but it is limited by the amount of oxygen that can be consumed by the cells. The second, anaerobic, takes over when the oxidative method is no longer sufficient. It does not require oxygen but produces acidosis and lactate — the famous “lactic acid” of athletes — and induces muscular fatigue.

For researchers, the question was which of these methods of energy production predominates in children. They brought together three different groups. Boys 8 to 12 years old, prepubescent, untrained adults and adult athletes, practicing high level endurance sports. The researchers then measure in the laboratory on an ergometer bike within each group the power delivered during an effort by each of these methods of energy production.

After the exercise, measuring heart rate, oxygen uptake, and lactate concentration in the blood allowed the scientists to see how quickly participants in the experiment were recovering from the test.

During the exercise, the untrained adults obviously tired faster than the athletes and the children. The latter actually use their aerobic metabolism to produce the energy needed for exercise and are less fatigued during high intensity physical activity. This predominance of aerobic metabolism is also found in adult endurance sports practitioners.

The children are therefore particularly well equipped to practice a physical activity that lasts. In truth, they are even better than the adult athletes!

The researchers also demonstrated the excellent recovery capacity of children. After the physical effort, the heart rate of the children returns to normal very quickly, that of adults pounding twice as long. And as if that was not enough, lactate, which they produce in lesser quantities, is eliminated faster than in adults. Faced with fatigue, children recover so much faster than adults.

So when you face your son or daughter in a race, it’s actually a miniature marathoner better armed than you for stamina that you are challenging without knowing it. And while at the end of the race, you’ll be busy wiping the sweat from your brow, catch your breath and lower your heart rate, the child will have to sit down for only two minutes before going back to track and start running again.

Shakes Gilles

Editor of The Talking Democrat. He enjoys bike riding, kayaking and playing soccer. On a slow weekend, you'll find him with a book by the lake.