Your spine's health is affected by your choice of backpack. The American Chiropractic Association and American Academy of Orthopaedic Surgeons suggest that children's backpacks should not weigh more than 10 to 15 per cent of their body weight. But most young people carry far heavier loads. Research has shown that a lot of back pain is caused by carrying overloaded backpacks. A 2007 study published in the Journal of School Health looked at the influence of school bags on back pain and found that of the 531 children and adolescents studied, 49.2 per cent reported pain due to their backpacks and nearly a quarter had to receive medical treatment. Those carrying a backpack weighing over 11 per cent of their body weight were more likely to have back pain. than weights of under 10 per cent. Researchers' recommendations 1 Carry backpacks that weigh less than 10-15 per cent of your body weight, so if you weigh 120 pounds, your backpack shouldn't weigh between 12-18 pounds. 2 Use a backpack that has a waist belt - and fasten it up! This will help to distribute weight more evenly across your body. 3 Wear both straps of your backpack to avoid posture problems. Wearing only one means you lean more to offset the weight, straining your neck and shoulders. 4 To minimise the weight, remove items you don't really need, and have regular weigh-ins to be sure your pack doesn't exceed recommendations. 5 Where possible, heavy books should be replaced by electronic media or keep a second set of books at home. 6 If you have a locker use it regularly throughout the day instead of carrying your whole day's worth of books everywhere you go.