The weight of a book exerts a different amount of pressure on the back based on posture and other factors, equating to more force. The angle of a person’s spine also changes how that force applies to the spine. The effect a single book in a person’s bookbag equates to the weight of seven books on the spine. When a person leans forward just 20 degrees, it is more like the effect of having 12 books in the bag. Studies are ongoing as to the effect the additional weight has. Currently backpacks have been connected with back and neck pain, intervertebral disc compression, altered gait and posture, and plantar foot pressure. The amount of weight recommended in a backpack varies based on the size of a person to reduce the negative effects of carrying a backpack. For children whose bodies are still growing, studies have suggested a load up to 10% of the child’s body weight. For young adults, the studies suggest a safe weight is up to 15%. Adults around college age can carry between 15 and 20% of their body weight safely.
One of the greatest concerns is that ligaments are the first affected by having too much weight in the backpack. When inflamed and stressed, ligaments can reduce a person’s mobility and movement range. However stress on a muscle strengthens the muscle. When stress is applied over long periods of time, it causes intractable pain, and bookbags create undue stress on those muscles. Over time, wear and tear coupled with the additional stress causes the muscles and ligaments to begin to degenerate. In the worst cases it will require surgery to repair the damage. To reduce the risk of this kind of long-term damage, the article provides the following preventative suggestions.
- Keep in mind the multiplier for how much a book weighs in a bookbag (7x the weight for each book; 12x times greater when a person leans forward 20%), and make sure not to exceed the study recommendations based on age and size.
- Only carry what you need; avoid overpacking.
- When possible, get digital books to reduce the weight of items in the bookbag.
- Be aware of your posture and maintain good posture when carrying a backpack.
- Always wear both bookbag straps and keep the bookbag close to your body.
- Work on your core and leg muscles to better distribute the weight.
For more details on these suggestions and to review the data about personal weight and backpacks, check out Impact of the Backpack on the Spine.