Exercise is known to increase bone development in teenagers, but what effects do exercise and minor physical activity have on the bones of children? A recent study published in Pediatrics is one of the first to examine the effects of low-impact everyday activities on bone density in children.

Researchers examined the relationship between physical activity and bone measurements in a sample of 368 four- to six-year-old children, using a combination of motion readings, parental reports on their children’s activities, and similar reports on the number of hours their children spent watching television.

Bone density and bone mineral content were measured for the entire skeleton, and specifically at the hip and spine. Parents rated their children’s activity level by reporting the daily hours their children spent watching television and by attaching a motion-recording belt to each child to keep track of time spent being physically active.

High motion levels and physical activity ratings were associated with higher bone density and mineral content in both boys and girls. Comparisons showed a 12 percent greater hipbone content in the most active children, compared to children in the least-active group. Also, girls who watched more television tended to have lower bone densities than those who watched less. Boys showed a greater level of total physical and vigorous activity than girls, which may account for their higher bone densities.

These findings suggest that exercise, or even mild physical activity, may increase bone density in children. Do your best to control the number of hours your children spend in front of the tube, and encourage them to be physically active whenever possible.

Reference:

Janz KF, Burns TL, Tomer JC, et al. Physical activity and bone measures in young children: the Iowa Bone Development Study. Pediatrics June 2001:107(6), pp 1387-1393.