The teens, couch potatoes natural?

teen(Quebec) You find that your teen is looking more and more like a “couch potato”? But he who was a sportsman child, is it possible? Yes, it is, but know that it’s not necessarily laziness if it becomes a little soft side: it could be that teens are biologically made like that, a recent British study.

The experiment, published online recently on the website of the scholarly journal Medicine & Science in Sports & Exercise, was to install accelerometers the size of more than 300 children 5 years of the city of Plymouth, one week per year until the age of 15 years. By registering children gear changes, accelerometers have thus given an idea of ​​their level of exercise practically from infancy through adolescence.

“To our knowledge, no other study has objectively measured physical activity each year in a cohort throughout childhood and adolescence,” write the authors, led by Brad Metcalf, School of Medicine of the University of Exeter.

Results: Overall, children are much exercise to eight years to five years. But once inside the preteen, some lazy settled quietly. Between 9 and 15 years, in fact, the researchers found that the total physical activity decreased 30% for girls and 20% boys.


Interestingly, the biggest decline among girls seems to be explained mainly by the fact that puberty occurs earlier at home, and the trend is the same among wealthier than among disadvantaged – the study also included socioeconomic indicators . Similarly, the reduction was similar at home and at school.

This declining physical activity in adolescence has already been found in other studies, but his reasons are still not clear. Some see it as an effect of the social and academic environment that changes past 12 years or so, but Mr. Metclaf and his colleagues argue in turn for a biological explanation. “The differences between the sexes, the tendency according to age and physical activity are systematic in our data, and says also said systematic control, they write. He is not sure if it is a biological control or socio-environmental, but our data do not support the latter avenue. […] The thesis of the biological cause, it is supported by our data, since physical activity is strongly associated with puberty. ”

Rapid conclusion …

However, this conclusion seems a bit fast in the eyes of Benedict Arseneault, a researcher at the Institute of Cardiology and Pneumology of Quebec who is interested (especially) the prevention of heart disease – and thus to exercise. “Right now, I’d say it’s speculative. […] The data are consistent with the biological explanation, but does not prove, “he said.

It notes, however, that the study also brings shades of unpublished and potentially very important on the decline of physical activity in adolescence. The authors could indeed measure the intensity of the exercise, and thus found that the decline is mainly concentrated in light activity – means and intense exercises are falling slightly, but significantly less. But these light exercises are often related to lifestyle, “which could have implications for future interventions [health authorities],” the researchers write.

“The data are pretty clear on the fact that young people, both children and teenagers, are almost as many organized sports before, confirms for his part said Arseneault. But it’s the slight physical activities that fall, and here we are talking about going to school on foot or by bike, spontaneous games, children that will make a strong, going to the park, etc. In return, of course, are increasing sedentary activities. The authors of the study did not measure, but we know that time spent in front of a screen is clearly increasing. ”

The Stopru