Researchers have identified yet another health risk linked with sedentary lifestyles, particularly among boys during the critical growth period of adolescence.
Teenage boys who spend more time in front of screens tend to have lower bone mineral density (BMD), according to a study of Norwegian students presented April 4 at the World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases.
The study, presented by lead author Dr. Anne Winther of the Arctic University of Norway, observed an adverse correlation between the time teenage boys spent in front of screens and their bone mineral density, which the author identifies as “a strong predictor of future fracture risk.”
As the authors point out, the human skeleton grows continually from birth, reaching its maximum strength and size just after adolescence. Along with diet, physical activity has a direct impact on this process, so the researchers hypothesized that inactivity might compromise skeletal development.
To shed some light on the question, researchers studied a sample group of Norwegian teenagers aged 15 to 18, including 463 girls and 484 boys. Data was collected on the teenagers’ screen habits and other lifestyle factors, and each participant’s bone mineral density was evaluated in three ways: at the hip, at the femur neck, and for the body overall.
According to the results, boys spend more time than girls in front of the computer, and this higher screen time was associated with lower bone mineral density on the whole. In the female group, intriguingly, the opposite effect was observed. Girls who reported four to six hours of screen time per day had a higher bone mineral density than those who spent less than 1.5 hours per day in front of a computer or TV. This difference could not be explained by adjustments for the other lifestyle factors evaluated.
For Winther, the results seen among girls merit further study, but the findings for boys are unequivocal.
“The findings for boys … clearly show that sedentary lifestyle during adolescence can impact BMD and thus compromise the acquisition of peak bone mass. This can have a negative impact in terms of osteoporosis and fracture risk later in life.”
According to the International Osteoporosis Foundation (IOF), one in five men over the age of 50 suffer from osteoporosis.