Last updated May 3, 2018 at 9:54 am
There is a very good reason that kids seem to be able to run and run and run without tiring – they’re essentially mini endurance athletes with muscles resistant to fatigue and with a superhero-like ability to recover.
Parents know the feeling – their child is able to sprint here, then there, and then back again, leaving the adult lagging behind. Even after a fully grown adult has had to tap out, the child is still going like the proverbial bunny.
Now scientists from France and Western Australia’s Edith Cowan University (probably in an exhaustion-induced haze after chasing their children around the park) have discovered just what gives kids this never-slow-down superpower.
They not only have fatigue-resistant muscles, but they are able to recover very quickly from high-intensity exercise. In fact, even a well-trained adult endurance athlete can’t compete when it comes to recovering.
“During many physical tasks, children might tire earlier than adults because they have limited cardiovascular capability, tend to adopt less-efficient movement patterns and need to take more steps to move a given distance,” said Sébastien Ratel from the Université Clermont Auvergne.
“Our research shows children have overcome some of these limitations through the development of fatigue-resistant muscles and the ability to recover very quickly from high-intensity exercise.”
Going like the clappers
The researchers pitted three different groups against each other – eight- to 12-year-old boys and adults of two different fitness levels – to perform exercise tasks on stationary bicycles.
While the boys and untrained adults were not regular athletes or fitness fanatics, the endurance athlete group was made up of some of the country’s best triathletes, long-distance runners, and cyclists.
And boom, the kids handed out a spanking to the average adults in every measurement of fitness.
Not content with that, they were also in better shape than the elite athletes when it came to recovery.
The tests measured their aerobic capacity (using oxygen from the blood), and anaerobic capacity (which doesn’t use oxygen and produces muscle fatiguing lactate).
To find out how quickly they were recovering, the scientists also checked their heart-rate, oxygen levels and lactate-removal rates after the exercise.
“We found the children used more of their aerobic metabolism and were therefore less tired during the high-intensity physical activities,” says Ratel.
“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.”
Essentially, they can go harder for longer before producing lactate, and when they do they can get rid of it quicker, letting them bounce back up and go again sooner.
“This may explain why children seem to have the ability to play and play and play, long after adults have become tired,” said Ratel.
More than just being outrun in a park
The study not only reveals the reason even fit adults can’t keep up with their kids, it could change the way we identify tomorrow’s sporting superstars.
“Many parents ask about the best way to develop their child’s athletic potential,” said Ratel.
”Our study shows that muscle endurance is often very good in children, so it might be better to focus on other areas of fitness such as their sports technique, sprint speed or muscle strength. This may help to optimize physical training in children, so that they perform better and enjoy sports more.”
However, it also reveals how our bodies and fitness changes as we age.
“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.
“Our research indicates that aerobic fitness, at least at the muscle level, decreases significantly as children move into adulthood — which is around the time increases in diseases such as diabetes occur.”
“It will be interesting in future research to determine whether the muscular changes we have observed are directly related to disease risk. At least, our results might provide motivation for practitioners to maintain muscle fitness as children grow up; it seems that being a child might be healthy for us.”
The research was published in Frontiers in Physiology