Inactive teens develop lazy bones (literally)

Inactive teens have weaker bones than those who are more physically active.

Researchers at Canada's Vancouver Coastal Health Research Institute, measured the physical activity and bone strength of 309 teenagers over a specific four-year period that is crucial for lifelong, healthy skeletal development. Lead researcher Leigh Gabel, who is completing her PhD in orthopaedics says the findings highlight the importance of physical activity for young people,

"We found that teens who are less active had weaker bones, and bone strength is critical for preventing fractures."

Gabel and her team used high resolution 3D X-ray images to compare differences between young people who met the daily recommendation of 60 minutes of moderate-to-vigourous physical activity per day and those who got less than 30 minutes a day. The orthopaedic researcher says that there is a vital four-year window - between the ages of 10 to 14 for girls and 12 to 16 for boys - when as much as 36% of the human skeleton is formed and bone is particularly responsive to physical activity.

"Kids who are sitting around are not loading their bones in ways that promote bone strength. That's why weight-bearing activities such as running and jumping and sports like soccer and basketball are important. Bone strength is a combination of bone size, density and microarchitecture. While boys had larger and stronger bones throughout the study, both boys and girls responded in the same way to physical activity."

Heather McKay, a professor in orthopaedics and family practice at the Centre for Hip Health and Mobility says that school-and community-based approaches are needed to make it easier for children and families to be more active,

"The good news is that activity does not have to be structured or organised to be effective: short bursts such as dancing at home, playing tag, chasing your dog or hopping and skipping count, too."

Professor McKay says that parents can also support healthy choices by being role models and limiting screen time,

"The bottom line is that children and young people need to step away from their screens and move to build the foundation for lifelong bone health."

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