Friday, January 29, 2010
Image by Mike Baird.
For a couple weeks now I have been waiting to discuss a very important new paper published on data from the Canadian Health Measures Survey (CHMS). For
The CHMS is a nationally representative survey of 5,000 Canadians, which is cool, but that is not what makes it so special. The CHMS is unique because, unlike most large surveys, everything is directly measured. So participants don't just report their height and weight - they are measured by researchers. So is physical fitness, physical activity, and a ridiculous number of other variables including everything from cholesterol to oral health and infectious disease. This is a huge deal, since people tend to over-report height, under-report weight, and forget a whole lot else. So information from a study like this has quite a bit less error than most traditional surveys. And the best part of the whole thing is that researchers have access to this data for free!!! So far the data has only been released to Statistics Canada researchers, but in a few months it will be opened up to the rest of us, which is absolutely awesome. And of course it will also give us tremendously valuable information about the health of Canadians. Which is what brings me to one of the first studies to be published using the CHMS data, titled Fitness of Canadian Children and Youth: Results from the 2007-2009 Canadian Health Measures Survey.
As the title suggests, this paper reports the current levels of both fitness and obesity in Canadian youth. What's more, they also compare the data to similar information collected in 1981 as part of the Canadian Fitness Survey. The result is a very interesting portrait of the health of Canadian youth.
So how does the current generation stack up? Not surprisingly, in comparison to children in 1981, current Canadian youth are heavier, have larger waist circumferences, poorer grip strength, and even worse trunk flexibility than in 1981 (interestingly, they are also taller, although it doesn't look like it accounts for the increased weight). Unfortunately aerobic fitness in 1981 was measured using a slightly different protocol than the current study, so the authors did not compare the two, although it would be a pretty safe bet that aerobic fitness is lower now than in 1981 as well. I have used the paper to graph some of the most interesting variables below, for boys and girls aged 11-14. All of the differences are statistically significant, and all of the variables have moved in an unhealthy direction.
What is the take-home message?
This paper confirms what we were all expecting - Canadian kids are heavier and less physically fit than ever before, and this is a very real concern for all of us. People tend to gain weight and become less fit with age. The authors point out that if this generation follows the same body weight trajectory as has been seen in previous generations, "the average 11- to 14-year old Canadian of today will be overweight by age 36". This means that we can expect this generation to experience increased risk of chronic disease at a younger age than previous generations as well. A sobering message to say the least, but it is an important reminder of the importance of these issues to the health and well-being of our society.
The paper itself is available for free on the Health Reports website, and I would urge everyone to take a look. The paper has a very nice figure that contrasts the silhouette of a current 12-year old with that of a 12-year old from 1981, and the figure alone is worth downloading the entire paper (there are also are quite a few variables that I didn't have room to mention in this post). And finally, be sure to check out the companion paper titled Fitness of Canadian Adults: Results From the 2007-2009 Canadian Health Measures Survey, which I hope to discuss on the blog in the future (although in general, the results seem similar to what was shown in children in the graphs I've shown above). The current issue of Health Reports also contains what is likely to be an influential paper on the important role of quality control in the use of accelerometers for the measurement of physical activity, but that will have to wait for another day as well.
Have a great weekend!
Mark S Tremblay, Margot Shields, Manon Laviolette, Cora L. Craig, Ian Janssen, & Sarah Connor Gorber (2010). Fitness of Canadian Children and Youth: Results from the 2007-2009 Canadian Health Measures Survey Health Reports, 21 (1), 1-7
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