GRANADA, Spain — It is an incredibly common sight in schools all over the world; students rushing home or between classes carrying backpacks filled to the brim with textbooks and notebooks. Homework is a big part of most teachers’ lesson plans, and that means students must lug their books home after most school days. Now, a new study has established just how much backpack weight is too much.
Researchers from the University of Granada and Liverpool John Moores University have determined the maximum weight that children, more specifically elementary school students aged between 7-12, should be allowed to carry in their bags: 10% of their body weight when using a traditional backpack, and 20% of their body weight when using a rolling backpack.
Weight recommendations have been made in the past for traditional backpacks, since they are by far the most popular form of backpack all over the world, but no recommendations had ever been made for rolling backpacks until now. Furthermore, over 40% of school students in Spain use rolling backpacks, so researchers from the University of Granada set out to perform their own study that would incorporate rolling backpacks.
For the study, the torso and lower limb posture of 49 elementary school students was assessed. Each student’s posture was analyzed while performing three different actions: walking freely while carrying no weight at all, walking while carrying a normal backpack, and walking while pulling a rolling backpack. For both types of backpacks, the test subjects were carrying either 10%, 15%, or 20% of their body weight.
A 3D motion capture device, similar to those used in animation and video games, was used in conjunction with statistical techniques to analyze each child’s movements and the impact of the weight on their bodies. Researchers found that the majority of stress was being placed on the hip and torso, with minimal impact on knees and ankles.
The study’s authors made a point to note that the rolling backpacks put much less stress on the body in general, and allow children to walk almost identically to how they would while carrying nothing at all.
The study is published in the scientific journal Applied Ergonomics.