In general a child's backpack should never exceed 10% of their body weight as the added stress to their backs can cause deformation as well as back injuries.
Although it may feel and look like spinal discs slip out of place, it's actually a herniation of the inner disc.
An improperly set up work station can cause unnecessary pressure on the spine!
Whiplash the symptoms you need to know
Keeping Your Spinal Discs Healthy