Is it OK to carry a backpack on just one shoulder if you use a different shoulder every day?
- Luke*

It's not OK if the backpack is heavy (10% of your body weight or more). That's just too much weight for each shoulder to bear on a regular basis. You can still hurt yourself.

If a backpack is heavy, you can strain your muscles from carrying it on one shoulder just for one day. That's why the best way to carry a heavy pack is by using two straps. It balances the weight across both shoulders and over your back.

Doctors and physical therapists recommend that people carry no more than 10% to 15% of their body weight. So if you weigh 120 pounds, your backpack should be no more than 12 to 18 pounds. If you weigh 150, it should be no more than 15 to 20 pounds, etc. And these amounts are for using both straps. To carry a pack on one shoulder safely, you'll have to go for much, much less than that.

The average textbook can weigh in at 3 to 5 pounds. So if your pack has a couple of textbooks, a notebook, and water bottle in it, you're already pushing the limits for a two-shoulder pack. That's without adding a laptop or other things you might want to carry around.

Why are the experts so strict about backpacks? Mostly because a backpack is a weight you carry around each and every day. For most of us, our high school and college years are the only time we'll carry around this much on a regular basis — and for several years. Yet it's also a time when our bodies are still growing. That leaves us more vulnerable to injury at the point in our lives when we're carrying the most weight.

The good thing is, our teens are also a time in our lives when we become more aware of and informed about our bodies. We're better able to take care of ourselves than we were as kids. Asking questions like this one (and thinking through the pros and cons as you are doing) helps us make good decisions.

Reviewed by: Kate M. Cronan, MD
Date reviewed: September 2011

*Names have been changed to protect user privacy.