All those hall monitors exhorting students to stand up straight may be on to something: A new study finds that a typical student hunching under the weight of a backpack could experience more than 11 times that weight in stress on their backs.
A new study in the journal Surgery Technology International tested the stresses on a model spine from backpacks laden with with weights from one to 100 pounds and worn using both straps. The researchers gauged compression both when the spine was straight and when it was tilted forward 20 degrees—about the typical angle of an adolescent slouch. For every pound of weight added to the backpack, the researchers found 7.2 times that weight in compression on a straight spine, and 11.6 times the stress on a spine hunched over.
In spite of the move to more digital and shared textbooks in schools, the American Occupational Therapy Association estimates that more than 79 million schoolchildren wear backpacks to school. Medical guidelines stress limiting backpacks to no more than 10 percent of a child’s weight. For the average 5th grader, that would mean carrying no more than six pounds in total. But (based on a highly unscientific sample of 5th grade reading textbooks collected here at Education Week), each book can weigh more than two pounds. And in middle and high schools, where students regularly haul packs from class to class all day, individual textbooks can top six pounds. Add in books for a few more subjects, random handfuls of homework and returned tests, and all the other paraphenalia that tends to accumulate in kids’ backpacks, and it’s easy to go over the recommended weight. One 2009 study by the University of Cincinnati College found more than 1 in 3 students who regularly wore backpacks had back pain related to their weight.
Only a few states actually limit the weight of class materials. California, for example, requires publishers to provide a lighter alternative like a digital text if a paper book weighs more than three pounds in kindergarten through 4th grade, four pounds in grades 5 to 8, or five pounds in grades 9 to 12.