Feb. 3, 2010 -- A backpack loaded with books may set your child up for spine strain rather than success.
A new study shows heavy backpacks place significant strain on children's spines and may lead to back pain.
Researchers say it's the first study to use magnetic resonance imaging (MRI) scans to document compression of the spinal discs and spinal curvature caused by a typical school backpack load on children.
"Backpack loads are responsible for a significant amount of back pain in children, which in part, may be due to changes in lumbar disc height or curvature," write researchers Timothy B. Neuschwander, MD, of the University of California, San Diego, in Spine.
"Over 92% of children in the United States carry backpacks that are typically loaded with 10% to 22% of their body weight," write the researchers. "Thirty-seven percent of children aged 11 to 14 years report back pain, the majority of whom attribute the pain to wearing a school backpack."
In the study, researchers used an upright MRI scanner to image the spines of eight children, average age of 11, while standing first with an empty backpack and then backpack loads representing 10%, 20%, and 30% of the children's body weight (9, 18, and 26 pounds, respectively).
The results showed two key spinal measurements changed as the weight of the backpack increased. Heavier weights caused compression of the discs that act as a cushion between the bones of the spine.
Researchers say that disc compression was especially great in the lower spine at heavier backpack weights.
Heavier backpack loads were also associated with increased curvature of the lower spine. Half of the children had a significant spinal curve even with the 18-pound backpack. Most of the children had to adjust their posture to adapt to the heaviest, 26-pound backpack load.
The amount of back pain reported by the children also increased as backpack load increased. At the heaviest load, the average pain score was nearly 5 out of 10 for the children.
Researchers say the results show heavy backpacks cause compression of the spinal discs and increased spinal curvature that are related to the back pain reported by children.
In the study, children wore the backpacks with the straps over both shoulders, but researchers say the spinal curvature could be even worse if the backpack were carried over one shoulder as many children do.