Friday, February 5, 2016

Are Canadian children in a physical activity crisis?

By Brian Timmons, PhD

There is an activity crisis in Canada. Canadian kids do not get enough physical activity for healthy growth and development. How do I know? Because according to the ParticipACTION Report Card on Physical Activity for Children and Youth only 9% of kids ages 5 to 17 meet the Canadian physical activity guidelines. We are raising a generation of children that will not outlive their parents. It's serious.

In a couple of weeks, I will be speaking at the Chronic Disease Prevention Alliance of Canada (CDPAC) conference in Toronto. My presentation is in the last session on the last day of the conference (a coincidence, I'm sure). Not to steal my own thunder, but in that presentation I will suggest that the physical activity landscape among children in this country may not be as bleak as we are led to believe.

To do so, we have to start at the beginning. How much physical activity do kids need for healthy growth and development? Do you follow twitter? Are you on the Facebook (yes, I call it "the" Facebook)? Lots of organizations insist that kids "need" 60 min every day. Do you check out ParticipACTION much? The message is the same: kids need 60 min every day. Even the World Health Organization recommends 60 min of physical activity every day. And if kids don't get it? Well, that's when the crisis sets in. Of course, these recommendations are based on the evidence, right?

A reasonable question at this point would be: what does the evidence say? Let's take the Canadian situation. The current Canadian physical activity guidelines are based on the evidence synthesized in a systematic review conducted by Janssen and LeBlanc. What did these authors find? They wrote, "The minimal and optimal doses of physical activity required for good health in children and youth remain unclear". They went on to write, "The need for children and youth to engage in physical activity on a daily basis to maintain good health was not supported by the evidence reviewed here". Indeed, recommendation #1 from these authors was: "Children and youth 5-17 years of age should accumulate an average of at least 60 minutes per day and up to several hours of at least moderate intensity physical activity". An "average" of at least 60 min per day. Not 60 min every day. And the reason they didn't recommend the latter is because there is no evidence for it. They didn't even say it had to be moderate to vigorous physical activity (MVPA), just, "at least moderate".

So how did our Canadian physical activity guidelines come to read 60 min of MVPA every day? You can read about that here.

Then there is the problem of measurement. The statistic that only 9% of Canadian school-aged children meet the guidelines is based on data from the Canadian Health Measures Survey (CHMS). The CHMS uses accelerometry (which has its own issues; dare I say "epoch") to objectively monitor physical activity of its participants. Unfortunately, the rigid definition of the guideline creates a disappointing number of kids who are actually active 60 min at a moderate to vigorous intensity every day.

But wait. Is it all that bad?

What is often lost in the publications and press releases is the finding that 61% of kids accumulate at least 60 min of MVPA on at least 2 days of the week and that 44% of kids accumulate at least 60 min of MVPA on at least 3 days of the week. Why is this important? Well, because Janssen and LeBlanc wrote, "there is strong and consistent evidence based on experimental studies for several health outcomes that participating in as little as 2 or 3 hours of moderate-to-vigorously intense physical activity per week is associated with health benefits". And remember, experimental studies are usually those that impose physical activity on top of the child's normal activity routine. One interpretation, therefore, is that the majority of Canadian kids are, in fact, active enough for health, isn't it? Another finding from the 2007-2009 CHMS that never appears on twitter is that almost 50% of Canadian kids accumulate at least 30 min of MVPA on at least 5 days of the week. This fits into Janssen and LeBlanc's evidence-based statement of 2 to 3 hours of MVPA per week as well, doesn't it?

And 50% is better than 9%.

But wait, there's more...

There are also Canadian physical activity guidelines for the early years (0-4 years), and I can proudly say I was involved in their development. These guidelines recommend that children ages 1 to 4 years should accumulate at least 180 min of physical activity at any intensity every day. Is this evidence-based? Well, you can read about that here. The important question is what proportion of Canadian preschoolers meets these guidelines? The CHMS says 70%. Hardly a crisis.

So where does this leave us?

As a father of 3 kids between the ages of 5 and 17 years, I guess I wonder is 60 min of MVPA every day necessary for their healthy growth and development. If they only get an "average" of 60 min of MVPA on any given week (meaning some days may be more active than others), does this have major implications for their health? If occasionally they spend all day indoors and play video games or board games, does that make me a bad parent? As a scientist, I wonder the same: is 60 min of MVPA every day necessary for children's healthy growth and development? I wonder if the way we measure adherence to the guidelines and the guidelines themselves are flawed to a point where our interpretation is tainted. I wonder what the scientific community can do to avoid the activity crisis rhetoric. Government and non-government agencies are investing in initiatives designed to promote physical activity, in part, because of the apparent activity crisis. Are these initiatives needed it? Are they worth it? If you're in Toronto this year on February 25th, drop into our symposium Thursday afternoon to find out.

Do I think more is better when it comes to physical activity for kids? Yes.

Do I think Canadian children are in a physical activity crisis? No.


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