Now that school is in session, your child’s backpack is probably becoming the catch-all for everything — books, homework, snacks, sports gear and other belongings. It’s important to keep an eye on backpacks, not only to catch any moldy apples collecting at the bottom, but also to ensure they aren’t weighing your child down.

Backpacks that are too heavy, aren’t worn properly or have uneven weight distribution can cause muscle and joint aches and pains, posture problems and even injury.

Most backpack injuries happen because the backpack is too heavy. The backpack should not weigh more than 15 percent of your child’s body weight. If your child weighs 100 pounds, the backpack should not weigh more than 15 pounds.

Getting the right fit is also important. Here’s how to help kids make sure their backpack fits correctly:

Wear both straps. They should fit comfortably on the shoulders and under the arms.

Adjust the straps so the bottom of the backpack rests in the contour of the lower back. Don’t let it sag down toward the butt.

Adjust the straps so the backpack is centered evenly in the middle of the back.

If the backpack has a waist strap, use it. This helps distribute some of the weight onto the pelvis, which relieves pressure on neck, shoulders and back.

See the entire lesson about backpack safety at Health Powered Kids. It’s designed for kids ages 9-14. They will learn that there are both safe and risky ways to wear their backpacks. They will also assess their own backpack safety and learn how to make changes if needed.

This article originally ran as a post in Allina Health’s Healthy, Set, Go blog. Read more stories like this at allinahealth.org/healthysetgo.