Whether kids are heading off to their first year of Pre-K or their last year of high school, they all probably have one thing in common: the backpack they’re hoisting.

Though backpacks are an efficient way to carry school items, they can sometimes harm more than they help. More than 6,300 youngsters between ages 5 and 18 were treated in emergency rooms for backpack injuries in 2016, according to the Consumer Product Safety Commission.

“Backpacks help distribute the weight of the load among a child’s shoulder and back muscles, but if they’re not worn correctly or they’re too heavy, they can cause muscle strain,” says Pablo Castañeda, M.D., chief of pediatric orthopedic surgery at Hassenfeld Children’s Hospital at NYU Langone in New York City. Some other experts say overly heavy packs can harm joints and increase a child’s fall risks as well.

Here, expert advice on how to choose, load, and wear backpacks properly.

The Features Your Child Needs

Look for a backpack that is sturdy but lightweight, no wider than your child’s body, and size-wise, extends from about 2 inches below the shoulder blades to the waist. Reflective strips can make your child more visible. And consider these features:  

Wide, padded shoulder straps. Skip drawstring backpacks, whose thin straps can dig into your little one’s shoulders and restrict blood flow to the area. This can lead to back, neck, and shoulder pain and temporary arm and hand numbness. And opt for backpacks with two straps. Those with only one strap can create an uneven load and strain muscles, Castañeda warns.

“You also need to make sure your child is wearing the backpack the way it’s meant to be worn—on both shoulders,” adds Sara Bohac, M.D., a pediatrician at the Cleveland Clinic.

Padded back. This helps protect kids from being poked by any sharp edges on objects inside the pack, such as the corner of a textbook, and makes the backpack more comfortable to wear.

Waist strap. Though not essential, this feature, which helps spread out the weight of backpack contents more uniformly, may be useful for children who have several textbooks to transport.

Wheels. A rolling backpack may be a good option if your child sometimes lugs around a lot of heavy items. But check school policy; some have banned this style of backpack because it can pose a trip hazard for other youngsters, clog up hallways, be difficult to maneuver up and down stairs, and may not fit in lockers. 

“It’s particularly an issue for younger elementary school-age kids, since a bag can start rolling down the hall and they don’t know how to control it,” says Jennifer Weiss, M.D., a pediatric orthopedic surgeon in Los Angeles and spokesperson for the American Academy of Orthopedic Surgeons.

Make Sure Kids Use Them Right

To help prevent injury, follow these steps:

Pack strategically. Try to place heavier items closest to the center of your child’s back and lighter items in the front of the pack, recommends the American Occupational Therapy Association (AOTA). But do make full use of all those nifty compartments and pockets so that most of the weight isn’t concentrated in just one spot. See a packing diagram here.  

Check the weight. When loaded, the backpack should not weigh more than about 10 to 20 percent of your child’s body weight, according to the American Academy of Pediatrics (AAP). (Some other national health organizations recommend a maximum of only 10 or 15 percent of your child’s weight, so consider erring on the lower side of the AAP’s advice, especially for young children.) You can weigh a loaded pack on your bathroom scale. 

More Back-to-School News

But about 70 percent of kids carry backpack loads that are heavier than recommended, according to a 2015 study published in the journal Applied Ergonomics.

And if your child is overweight or obese, his backpack should be about one-third lighter than is generally recommended, suggests another study in Applied Ergonomics published last January.

“These kids’ back muscles are already supporting a lot of weight, and you don’t want to add even more strain,” Bohac says.

So remind your children that school backpacks are for, well, schoolwork. They should carry only the items they need for the day and leave the rest at home or in their locker at school.

Do your part to lighten the load. If you’re packing a water bottle, for example, send it empty and have your child fill it at school. And if you have younger school-age children, go through backpacks with them each night and remove unnecessary items.

Teach kids how to pick it up properly. To lift a backpack, kids should bend their knees and use both hands to pick up the pack. “If you bend over at the waist, you can strain your back,” Weiss says.

Adjust the straps. The pack should be snug against your child’s back, with the bottom resting in the curve of her back, AOTA says. But straps should not be so tight (or the pack so heavy) that she struggles to put it on or take it off.

Consider e-books or an at-home set of textbooks. Some school districts are starting to replace textbooks with e-books, especially at the high school level. Almost half of all Advanced Placement (AP) and National Writing Project (NWP) teachers, for example, say their students use e-readers and tablet computers to complete assignments, according to a 2013 Pew Research Center survey.

But even if your district doesn’t offer this, you may be able to download some of your child’s books from textbook manufacturers’ websites. If that’s not an option, consider buying a second set of textbooks for your child to use at home (you may be able to find used books online).

“We often see the most back strain in middle schoolers, since younger kids don’t carry heavy books back and forth to school, and the high schoolers have graduated to tablets and lightweight computers,” Castañeda notes.

Help If They Have Pain

If your child complains of mild back pain and you think it’s muscle-related, you can give her over-the-counter pain medication, such as ibuprofen, and apply a heating pad or hot water bottle to the sore area for brief periods over a couple of days.

But if discomfort persists, see your pediatrician. “Most of the time, kids I see who have low-back pain related to wearing a backpack have another underlying issue, such as weak core muscles,” explains Heather Fenton, M.D., a spokesperson for the AAP. 

He or she could be experiencing another medical problem, such as scoliosis, which affects up to 3 percent of people and is most often diagnosed between ages 10 and 15. (Contrary to popular belief, wearing a backpack doesn’t worsen scoliosis, but it can sometimes make it more painful.)

If the lingering pain is muscle-related, your pediatrician may recommend specific back and core strengthening exercises or refer you to a physical therapist who can design a program for your child.