Wednesday, September 7, 2011
Sigh-provoking as that scene is, it speaks to the ongoing problems our children are having with over-sized, over-stuffed and over-loaded back packs causing back and shoulder pain and the potential long-term issues they may face thirty years later. Simply stated most pre-teens don’t have the body strength that is necessary to maintain an erect posture under the ridiculous loads they carry and this weight and its distribution put substantial stress upon their immature skeletons and in the case of one-strappers, their shoulders.
The question then is begged as to what are the proper guidelines and some good tips for buying, loading and wearing a backpack?
Let’s start with the weight of the backpack. It is generally agreed that no more than 10% of a child’s body weight when they are pre-teens should be loaded into the pack. As they become older the weight can increase to no more than 15% of their body weight. You want to put the heaviest weight at the bottom of the backpack and it’s a pretty good idea, especially with younger children to clean out their packs every one or two days as you will be amazed at what you might find that has gone missing or is unnecessarily adding to the weight of the backpack.
In addition to the weight however, one of the major principles involved in safely wearing a backpack is to distribute the weight over as much of the body as possible. Therefore, one of the things you want to look at is a shoulder strap that is thick and well padded. Look for a backpack that has lots of side pockets as these can be used to further distribute the weight around the trunk. You don’t want the backpack to go below the natural curve of the waist, as this increased length will put more force across the skeleton; remember force is a function of weight times the distance squared. Additionally, I usually recommend that the backpack have a plastic or thick rubber lumbar support to fit as close to the body as possible and, although considered nerdy clasping the waist straps is very important in reducing the drag of the backpack and keeping the load as close to the long axis of the skeleton as possible (remember, distance squared!).
A final word about one-strappers. These are the teens that carry twenty to thirty pounds of books and goodness knows what else on one shoulder and then coms home and complaining that his or her shoulder hurts. Really! Needless to say, although way cool, these shoulder bags are a bad idea.
While there have not been a sufficient number of long-term studies to make any definitive statements about the long term effects of carrying a heavy backpack (such as the oft-heard it causes a curved spine) these common sense tips and approaches to this yearly annoyance will serve everyone well and help your child avoid unnecessary aches and pains.
They just don’t have the body strength to remain erect under these very substantial loads, and it puts their skeletons under substantial duress.