Inactive Teens May Develop Weaker, Lazy Bones


Have you ever fallen into such a lazy slump that you could feel it in your bones? For certain inactive teens, this might literally be the case.

Inactive teens have weaker bones compared to others their age who are active, according to a study published in Journal of Bone and Mineral Research.

Credit: Giles Turnbull/Flickr, CC BY 2.0

“We found that teens who are less active had weaker bones, and bone strength is critical for preventing fractures,” said Leigh Gabel, lead author and Ph.D. candidate in Orthopedics at the University of British Columbia.

Over the course of four years, researchers at UBC and the Center for Hip Health and Mobility in Vancouver studied the bone strength and physical activity of 309 teenagers.

Using 3D X-rays, researchers compared teens who got the recommended 60 minutes of moderate to vigorous physical activity a day to those who got less than 30 minutes.

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Between the ages of 10 and 14 for girls, and the ages of 12 and 16 for boys, is a crucial time in their physical development — about 36 percent of their skeleton is formed during that time, and bone is responsive to physical activity.

Kids who are sitting around are not loading their bones in ways that promote bone strength,” Gabel explained.

Bones are living tissue; the more weight-bearing physical activity a person does, the more new bone tissue forms, making the bones stronger. Weight-bearing activities include running, dancing and sports like soccer.

Overall bone strength comes from a combination of bone size, density and the bone’s small, detailed architecture. Although the boys in the study generally had larger and stronger bones, both the boys and girls responded the same way to physical activity.

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The physical activity didn’t need to be organized or structured either. Shorts bursts of dancing, playing with your dog or running around at the park were just as effective.

The study’s co-author Heather McKay, professor of Orthopedics and Family Practice at UBC and the Center for Hip Health and Mobility, explained that parents need more community-based support to make it easier for them to encourage their children to detach from video games and other electronics to get active.  

“The bottom line is that children and youth need to step away from their screens and move to build the foundation for lifelong bone health,” McKay said.