Kids’ gear: That backpack is too heavy!

Every year, that school supply list gets longer — and while those pencils, notebooks, and glue sticks are boring, my kids at least look forward to one thing on the list — picking out a cool, new backpack.

They’re fun, and they’re functional — but if you have a kid (like mine) who takes home everything at the end of the day (afraid to leave something at school that he might need) — you might need to take a serious look at the gear your child is choosing, and how he is packing it up every day.

Why? Because heavy backpacks can wreak havoc on a child’s joints, muscles, and spine, and the effects could be long-term.

Manhattan physical therapist Karena Wu, of ActiveCare Physical Therapy, warns parents of the injuries that can occur when children carry heavy backpacks to and from school every day.

“When a heavy weight, such as a backpack filled with books, is incorrectly placed on the shoulders, the weight’s force can pull a child backward,” says Wu. “To compensate, a child may bend forward at the hips or round the back, which can cause the spine to compress unnaturally. The heavy weight might cause some kids to develop shoulder, neck, and back pain.”

Wu says kids should carry no more than 10 to 15 percent of their body weight in their packs. For example, a child who weighs 80 pounds shouldn’t be carrying around a bag that weighs any more than eight to 12 pounds — and much less if possible! If you’re not sure what that feels like, weigh the bag on a bathroom scale.

But it’s not just the bag’s weight that needs to be monitored; look at how your child wears the backpack. Some kids wear their packs too low, which Wu says also increases the stress on the spine. She says the pack should should rest evenly in the middle of the back and not sag down to the buttocks.

And some kids like to wear their packs over one shoulder, causing them to compensate for the extra weight by leaning off to one side — which can result in upper and lower back pain and a strain on the shoulders and neck.

Prolonged improper use can also lead to poor posture, especially for girls and younger kids who are smaller and may be carrying loads that are not in proportion with their weight.

Purchasing a safe backpack

The right backpack — when worn properly — is handy and useful. And backpacks are a good choice for school (as opposed to shoulder bags, messenger bags, or purses), because the strongest muscles in the body — the back and the abdominal muscles — support their weight. But before you give in to your tween or teen who just has to have that trendy pack — read these recommendations from the American Academy of Pediatrics about selecting the right one. Look for:

• A lightweight pack that doesn’t add a lot of weight to your child’s load. (For example, even though leather packs look cool, they weigh more than traditional canvas backpacks.)

• Two wide, padded shoulder straps; straps that are too narrow can dig into shoulders.

• A padded back provides increased comfort and protects kids from being poked by sharp edges of objects (pencils, rulers, notebooks, etc.) inside the pack.

• A waist belt, which helps to distribute the weight more evenly across the body.

• Multiple compartments, which can help distribute the weight more evenly.

Some schools allow rolling backpacks, which are ideal for heavy loads. Check your school’s safety regulations before buying one, because many schools don’t permit them as they could be a tripping hazard in the hallways. (They are also difficult to pull up stairs and roll through snow.)

Be wary of backpacks that have tight, narrow straps because they can dig into the shoulders and affect circulation and nerves. This can lead to numbness and weakness in the arms and hands.

And remember that to be worn correctly, the weight of a backpack should be evenly distributed.

Parents need to make sure the straps are tight enough for the pack to fit closely to the body.

School officials also warn of dangers to other children when some kids wear heavy backpacks:

• Students who carry large packs often aren’t aware of how much space the packs take up and can hit others with their packs when turning around or moving through tight spaces, such as the aisles of the school bus.

• Kids are often injured when they trip over large packs or the packs fall on them.

• Carrying a heavy pack changes the way children walk and increases the risk of falling, particularly on stairs or other places where the backpack puts the student off balance.

Encourage your child to take some extra time at the end of the day to decide what comes home and what stays in the locker.

You can also make sure your kids aren’t adding to their weight limit by removing laptops, cellphones, and video games.

And lastly, says Wu, there are ways to handle the backpack that can help avoid injuries:

“As with any heavy weight, they should bend at the knees and grab the pack with both hands when lifting a backpack to the shoulders,” she says. “Try to make sure all the stuff they carry is distributed; use all of the compartments, and put the heavier items like textbooks, closest to the center of the back.”

Most importantly, parents should watch their children handle their packs. If you see your child struggle to get the backpack on or off, or if the child is leaning forward consistently, it’s too heavy.

And if your child has back pain or numbness or weakness in the arms or legs, talk to your doctor or physical therapist immediately.

Monica DiClerico Brown is a cable television news anchor and freelance writer. She lives in Pearl River, N.Y., with her husband and two children.