Take the Ouch Out of Kids Backpacks

Dec. 5, 2005 -- Kids' backpacks need to lighten up.

So say researchers who watched 10 healthy children don backpacks of different weights.

The maximum load wasn't much more than what many children typically carry. Still, sensors showed that the weight produced pressure that could cut blood flow to the shoulder muscles.

"We recommend that backpack loads be minimized to promote comfort and safety," write Brandon Macias and Alan Hargens, PhD, of the University of California at San Diego.

Their report appears in the Archives of Pediatrics and Adolescent Medicine.

How Heavy Is Too Heavy?

It's hard to pinpoint a pound limit for kids' backpacks. Children come in all shapes and sizes, so some can carry heavier loads better than others, the researchers write.

Average backpack loads reportedly equal 22% of a child's body weight, according to the study. So for a 100-pound child, that works out to a backpack load of 22 pounds.

That's probably too much, write Macias and colleagues. They note that most students worldwide carry backpacks and that it's not unusual for kids to complain of shoulder pain and back pain.

Backpack Burden

The study included five boys and five girls who were about 13 years old and routinely wore backpacks.

First, the students wore an empty backpack. That was no problem, according to sensors on the backpacks' shoulder straps. Each backpack was placed in the same position over both shoulders and collarbones.

Next, the kids wore backpack loads equaling 10%, 20%, and 30% of their body weight. As the weight increased, so did the shoulder pressure.

The kids also rated any pain they felt on a 10-point scale, with 0 being no pain and 10 being the worst imaginable pain.

The kids' pain ratings rose along with backpack weight, peaking just below four points.

Pressure and Posture

Pressure on either shoulder for all three loads reached levels that could restrict blood flow to shoulder muscles, the study shows.

The pressures were particularly higher on the right shoulder. That's probably due to posture, which wasn't studied, the researchers write.

The kids only wore the backpacks for 30 seconds. Some couldn't stand the load any longer. Children typically carry backpacks for 30-60 minutes per day, write Macias and colleagues.

They note that while concern about kids' backpacks isn't new, the sensors add objective information supporting light backpack loads.

SOURCES: Macias, B. Archives of Pediatrics & Adolescent Medicine, December 2005; vol 159: pp 1186-1187. News release, University of California, San Diego.