As healthy humans our birthright is good postural alignment. As pre-school children we have upright posture, we have a full range of movement, we can express our physicality freely and easily.
Then a catastrophe is imposed on our bodies: we are sent to school.
We are made to sit for hours, and we carry heavy bags, and within a few short years we develop postural habits that we may spend the rest of our lives living with.
This is something that has got worse over the years: when I was at school, we had desks to leave our books and possessions in, and only carried in our bags what we needed that particular evening. Nowadays we expect schoolchildren to carry all their books around all the time, and the weight children are expected to carry about with them is disproportionate to their own weight and strength.
As you can see from this illustration, heavy back packs force the child to round her shoulders and poke her head forwards. Often backpacks are slung over one shoulder, so the weight is not evenly distributed. Scoliosis (curvature of the spine) is often a result of carrying a bag on one side, while the spine is growing.
You can help your child to maintain good posture.
Get the best possible bag for their back: have a look here http://www.ergonomicschoolbags.co.uk/ as a starting point for the sort of bag to look for. I advise padded shoulder straps, and a sternum and hip belt.
Help them empty their bags of unnecessary stuff. Only take what they need.
School lunches instead of packed lunches lessen the amount they have to carry.
Weigh your child's loaded backpack - it should weigh no more than 10% of his or her own bodyweight: if it weighs any more than this s/he will have to change their posture to respond to the load. Does your child's school really want to ruin their childrens' backs?
The bag should not be low on their bodies, and should end less than a couple of inches below the waist. If it's too low it will pull them backwards and they will respond by leaning forward.
Make sure the bag is worn over both shoulder straps, and not left hanging from one!
The smaller the bag, the less they can put in it! Within reason, keep the bag's size small, or they will fill it up with unnecessaries.
Bags with various pockets and compartments are a good idea for organisation.
Make sure pointy items are placed in parts of the bag where they cannot dig into your child's back.
This advice applies not just to children, but also to adults.............make sure that your sore shoulders, neck tension, upper back pain is not caused by carrying too much, in an inappropriate bag.