Was there ever a time when you were watching over your kid run and play all day that you wondered where they’re getting all their energy from?

A recent study sough to bring answers to that question as it found that kids’ muscles ward off fatigue much like how an elite endurance athlete does.

The study, which was published in Frontiers of Physiology, requested a variety of people including young boys, untrained men and endurance athletes to go through high intensity exercises to see how fast their muscles fatigued and recovered.

The researchers had the participants go through a spirited session on a stationary bike and discovered that the boys’ muscles did not get tired as easily, even when going through stress levels that were at par with endurance athletes.

“The picture we get is that, in a high intensity exercise bout, kids fatigue at the same rate as elite athletes,” said Professor Tony Blazevich, a researcher from Edith Cowan University.

“They may even recover more quickly than elite athletes … which might be why kids recover so quickly when they do bouts of play or activity.”

Are kids as fit as endurance athletes?

Tim Olds, a Professor of Health Science at the University of South Australia, relayed the study was intriguing but noted that it wasn’t accurate to say that the kids were just as fit as the endurance athletes.

“What it’s found is the way they recover more resembles endurance athletes, than untrained adults,” said Olds, who was not at all involved in any capacity with the study.

In order to understand why kids have such good endurance and recovery, you need to properly comprehend how the body generates energy, Olds said.

“There are two broad ways to generate energy: one is aerobically … the other process is anaerobically.”

Olds explained that anaerobic energy generation produces lactate and when high levels of lactate build up in muscles, it leads to fatigue.

“But kids don’t have as highly developed anaerobic systems as the average adult … therefore they don’t produce a lot of lactic acid, and therefore they don’t seize up after repeated bouts [of exercise].

“It doesn’t mean that these kids are super fit, it just means that they haven’t yet developed their anaerobic capacity.”

The study also showed the degree at which the boys’ blood cleared lactate was quicker than endurance athletes, letting them recover quickly.

What does this mean for young athletes?

Professor Blazevich said that aside from helping shed light on why 10-year olds appeared to be tireless, the study could also have some us in determining what to focus on in training young athletes.

“We’ve all noticed this and now we’ve got some evidence as to why,” he said.

“If we want kids to want to participate in sport and activity, we have to understand their systems so we know how best to train them. This shows us kids are actually pretty good at playing, stopping, playing, stopping, playing, stopping. So that might mean that playing sports where they just get to run around a lot is much more enjoyable than doing other forms of deliberate exercise like adults might do,” Blazevich remarked.

What’s more, it’s useful for families where kids want to achieve higher levels in sport, by identifying weak spots that need more work on, Blazevich said.

“It looks like their aerobic fitness is very good, so we might therefore target skill, because they’re usually less skilful, strength, because relatively they tend to be weaker, and their high intensity or sprint ability, because of course they are weaker in that than adults as well. So it allows us to target in youth athletes the areas they need for improvement,” he said.