backpack

By putting a heavy weight on your shoulders in the wrong way, the weight’s force can pull you backward. So people who carry heavy backpacks sometimes lean forward. Because of the heavy weight and this unnatural position, they can develop shoulder, neck, and back pain. If you wear your backpack over just one shoulder, or carry your books in a messenger bag, you may end up leaning to one side to offset the extra weight. You might develop lower and upper back pain and strain your shoulders and neck.