Heavy Backpacks Will Likely Lead to Injury

My children in middle school constantly complain that their backs are breaking from carrying around so many books in their backpacks. Are there any guidelines about how much weight they should be carrying and how to wear a backpack? - Over Burdened
Answer: Your children could be absolutely correct. Too-heavy backpacks could cause injury. According to a report from the National Association for Elementary School Principals, most doctors believe that children are at risk for muscle fatigue or injury to the spine or shoulders when they carry more than 20 percent of their body weight. This means that a child weighing 100 pounds should not be carrying a backpack of more than 20 pounds.
To determine if your children are in danger of possible injury, weigh your children's fully loaded backpacks, and then weigh your children. If their loads are too heavy based on the 20 percent guidelines, have them determine if everything in the backpacks must be carried to school. If so, you might consider buying or renting a second copy of one or more of their heavy books to keep at home, so they don't have to lug it home every night. Or you might drive them to school or the bus stop when their packs are too heavy. Another possibility is having the children use backpacks with wheels.
The correct way for children to wear a backpack is to place it over both shoulders. Putting it over just one shoulder could cause injury when the pack is fully loaded. Also, when the load is heavy, they should use the hip straps. The pack itself should be loaded with the heavier items closest to their backs.