Study: Sedentary Time Affects Bone Strength in Children

According to a recent study, adolescents and teens who are less active have weaker bone strength than more active individuals.

The longitudinal study included 173 girls and 136 boys aged between 9 and 20 years at baseline. Researchers examined influences of physical activity and sedentary time on bone strength using high-resolution peripheral quantitative computed tomography (HR-pQCT) at distal tibia (8% site) and radius (7% site), and used accelerometers to measure moderate-to-vigorous physical activity (MVPA) and sedentary time. HR-pOCT measurements were taken at most 4 times a year at the tibia (n = 785 observations) and radius (n = 582 observations).
____________________________________________________________________________________________________________________________________________
RELATED CONTENT
Broken Arm May Signal Poor Bone Health in African American Children
Nutritional Pearls: Is Drinking Milk Good For Your Bones?
____________________________________________________________________________________________________________________________________________

Overall, their findings showed that MVPA was a positive independent predictor of bone strength and bone volume fraction at the tibia and radius, total area, and cortical porosity at the tibia. Likewise, sedentary time was a positive predictor of cortical thickness, trabecular thickness, and cortical bone mineral density at the tibia. 

In addition, MVPA was a negative predictor for the load-to-strength ratio at the radius, and sedentary time was a negative independent predictor for total area of the tibia and radius and cortical porosity at the tibia.

“Our findings support the importance of [physical activity] for bone strength accrual and its determinants across adolescent growth and provide new evidence of a detrimental association of sedentary time with bone geometry but positive associations with microarchitecture,” the researchers concluded. “Future studies should evaluate the dose-response relationship and whether associations persist into adulthood.”

—Melissa Weiss

Reference:

Gabel L, Macdonald HM, Nettlefold L, and McKay HA. Physical activity, sedentary time, and bone strength from childhood to early adulthood: a mixed longitudinal HR-pQCT study [published online March 22, 2017]. J Bone Miner Res. doi:10.1002/jbmr.3115.