Children who carry heavy backpacks can suffer from spinal strain and acute back pain, a new study claims.
According to Dr. Timothy Neuschwander of University of California, San Diego, and his team magnetic resonance imaging (MRI) scans show compression of the spinal discs and spinal curvature caused by typical school backpack loads in children.
The experts conducted a study on eight children, with mean age of 11 years.
With the help of a special upright MRI scanner the image of the children's spines in standing position was developed, first with an empty backpack, then with increasing weights of 9, 18, and 26 lb.
These weights represented about 10, 20, and 30 percent of the children's body weight.
It was observed that two key spinal measurements changed as the backpack load increased.
Heavier weights caused compression of the intervertebral discs, which act as a cushion between the vertebrae (bones of the spine).
Especially in the lower spine, the disc height became smaller (reflecting greater disc compression) at heavier backpack weights.
Heavier loads were also associated with increased curvature of the lower spine, either to the right or the left.
Half of the children had a significant spinal curve even with the 18 lb weight. Most of the children had to adjust their posture to bear the 26 lb backpack load.
Dr. Neuschwander and colleagues wrote: "Low back pain in children may be worsened by discogenic [disc-related] or postural changes."
The study has been published in the January 1 issue of Spine.