Can Kids Exercise Too Much?

Last year, I did an episode called How Much Should Kids Exercise?, in which I stated that although children don't need a lot of intense physical activity to get the health benefits of exercise, at least 7 minutes of exercise per day is the minimum necessary to prevent weight gain, obesity, and chronic health risks.

But two recent occurrences involving kids and exercise got me thinking.

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The first is that my friend Joe DeSena, the CEO of Spartan racing, told me that his 8-year-old boy had just completed a 50K race, and had also run the Boston Marathon along with a variety of other impressive and grueling feats of endurance. The second is a recently published magazine article in The Atlantic entitled “How Far Is Too Far for Kids to Run?”

Don’t get me wrong - I am a huge advocate of increasing physical activity in children. I’ve talked about this in a previous episode called How to Get Kids Fit and I recently spoke at The431Project about ways that we can combat childhood obesity and get kids more active.

But how much is too much? 

How Much Exercise Is Too Much?

While many children are still sitting around playing videos games, other children are now exercising in extremely high volumes with an increasing number of young athletes training for and competing in long-distance endurance events such as triathlons, obstacle races, adventure races, and marathons.  Injury and growth reduction potential risks aside, this may actually increase the propensity for those same active kids to eventually quit exercising.

The 2011 National Athletic Training Association’s position statement sums this up quite nicely:

“Athletes who sustain recurrent overuse injuries may stop participating in sports and recreational activities, thus potentially adding to the already increasing number of sedentary individuals and the obesity epidemic.”

Should Kids Run?

Running is a particular culprit, because, as this study shows, children’s bodies (particularly their bones, joints, and soft tissue) simply don’t absorb the impact of running as well as adults. Another study shows that children have different running biomechanics and a smaller legs to body size ratio, which can lower their body’s ability to absorb impact.

And although it has yet to be definitely proven by science (as there are obvious ethical issues with a controlled study that forces kids to pound the pavement) repeated impact to immature joints could potentially cause injuries to joint cartilage or separation of growth plates – which can lead to lifelong joint pain and stunted growth.

The Atlantic article I mentioned earlier sites the Clinical Journal of Sports Medicine as saying:

“Training to run in a marathon, which is more than eight times the usual cross-country competitive racing distance, is an inappropriate activity for children and adolescents.”

Perhaps this is one reason the Boston Marathon sets a minimum age limit of 18 for participation.

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Ultimately, when it comes to running, I let my kids run as much as they’d like – but I don’t actually sign them up for any events that require them to pound the pavement for hours on end to simply reach the finish line. I believe that the cons outweigh the pros.

Instead, I encourage my kids to participate in sports and events that require brief bursts of physical activity, such as soccer or tennis, or longer bursts of activity that aren’t extremely energy-depleting, such as 1-mile obstacle races or children’s distance triathlons (or even a “run-walk” 5K).

Should Kids Lift Weights?

When it comes to weight training, it can be a different story altogether. As this excellent article from ExRx.net notes:

• Strength and power increases with proper weight training, even in children.

• Neuromuscular coordination improvement in children has been linked to repetitive practice of the specific skill (regardless of the skill investigated), and that includes weight training.

• Weight training is simply measured subjectively, and scaled according to a child’s own strength, which means that it is an activity that may be more suitable for children’s participation compared to sports where success is measured simply by victory or defeat.

Research shows that children can weight train for up to 15 hours per week with no deleterious effect to their hormones, growth plates, or health (and now you have a great excuse to get your kids out in the backyard to build that rock wall!).

Based on this, while I personally didn’t begin hoisting 10-pound dumbbells until I was 13 years old, my 6-year-old twin boys now join me in our weight room with their own tiny dumbbells, kettlebells, and medicine balls, and I let them carry and lift heavy objects as much as their heart pleases (while of course being careful to teach them proper lifting form to protect their little backs and joints).

The only caveat to this is that science has yet to prove that utilization of maximal weights is safe. Maximal weight is anything that a child can only feasibly lift one time, such as a heavy barbell squat or deadlift. So I don’t think weight lifting competitions are a good idea for a growing child.

Get-Fit Guy's Approach to Children and Exercise

Ultimately, the Get-Fit Guy take on childrens’ exercise is this: Let your kids lift heavy objects, move all day long, and sprint as much as they want, but be careful about putting them into activities that require chronic repetitive motion for hours on end. The research simply doesn’t yet show that this is safe for children – and frankly, they’ll have plenty of time to run marathons and do Ironman triathlons after they’ve gone through puberty.

If you have more questions about how much kids should exercise, then join the conversation over at http://ift.tt/1xq4tPg!

Boy lifting weights image courtesy of Shutterstock.