Inactive teens have weaker bones than those who are
physically active, according to a new study.
Researchers with UBC and the Centre for Hip Health
and Mobility, at the 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.
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 PhD
candidate in orthopedics at UBC.
Gabel and her co-investigators used high resolution
3D X-ray images to compare differences between youth
who met the daily recommendation of 60 minutes of
moderate-to-vigorous physical activity per day and
those who got less than 30 minutes a day.
The four-year window between the ages of 10 to 14
for girls and 12 to 16 for boys is a vital time
when as much as 36 per cent of the human skeleton is
formed and bone is particularly responsive to
"Kids who are sitting around are not loading their
bones in ways that promote bone strength, said
Gabel, which is why weight-bearing activities such
as running and jumping and sports like soccer,
ultimate Frisbee and basketball are important.
Bone strength is a combination of bone size, density
While boys had larger and stronger bones throughout
the study, both boys and girls responded in the same
way to physical activity.
We need school-and community-based approaches that
make it easier for children and families to be more
active, said co-author Heather McKay, a professor
in orthopedics and family practice at UBC and the
Centre for Hip Health and Mobility.
The good news is that activity does not have to be
structured or organized to be effective: short
bursts such as dancing at home, playing tag at the
park, chasing your dog or hopping and skipping
Parents and caregivers can support healthy choices
by being role models and limiting screen time. McKay
highlights simple yet effective tactics used in the
Action Schools! BC intervention where children and
their teachers took activity breaks throughout the
day during lessons.
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, said McKay.
For more information
The Journal of Bone and Mineral Research
Physical Activity, Sedentary Time, and Bone Strength
From Childhood to Early Adulthood: A Mixed
Longitudinal HR-pQCT study
The University of British Columbia