Screen Time Weakens Boys’ Bones

Here’s more incentive to encourage boys to minimize computer use. A new study presented at the World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, in Seville, Spain, in April, draws a link between screen time and diminished bone mineral density.

The research, published in Osteoporosis International With Other Metabolic Bone Diseases (2014; 25 [s2]), included 1,038 Norwegian boys and girls aged 15–18.

“When we explored associations between BMD and screen time in a multiple regression model that included adjustment for age, sexual maturation, BMI, leisure time physical activity, smoking, alcohol, cod liver oil and carbonated drink consumption, we found contrasting relationships,” the authors reported.

Data analysis showed that boys spent more time using a computer than girls did and that increased screen time was associated with higher BMI levels. More screen time was associated with less BMD in boys, but the same was not true for girls.

“In contrast, girls who spent 4 to 6 hours in front of the computer had higher BMD than counterparts who spent <1.5 hours of screen time each day; this could not be explained by adjustments for the measured confounders,” the authors stated.

“We see different associations between time spent in sedentary activities and BMD levels among Norwegian boys and girls, and these findings warrant further studies in other populations,” the authors concluded.