By Stephanie Stahl

Follow CBSPHILLY Facebook  | Twitter

PHILADELPHIA (CBS) — A new study looked at the impact heavy backpacks have on a child’s back. Sixty-four percent say they have back pain related to lugging around all their school stuff.

The typical student’s backpack is loaded with electronics, supplies, books, gym clothes, lunch and more. It’s estimated that about 70 percent of kids carry backpacks that are heavier than recommended.

The study shows all that weight can take its toll on the back. Research measured how wearing a backpack impacts the spine.

“For example, 10 pounds in your backpack, then the forces on the spine is 70 pounds of force,” study co-author Ken Hansraj said. “So if you’re struggling uphill 20 degrees, then the forces become 120 pounds of force.”

What Gets You To Sleep? Study Reveals Some Turn To Metal Music

Carrying too heavy a load puts children and teens at risk for long-term health problems because they’re stressing areas of the spine and core that are still growing.

It’s recommended that young students carry no more than the equivalent of 10 percent of their body weight.

That amounts to five pounds for a 50-pound 6-year-old; for a 150-pound teenager, the recommendation increases to 23 pounds and for a 200-pound adult, 40 pounds.

Experts say it’s important to use both straps and to keep them tight. Practicing good posture can also reduce pressure on the spine.

“Good posture is your ear above your shoulders and your angel wings back,” Dr. Hansraj said.

Students’ Health, Academics Improved With Later School Start Times, Study Shows

Fourteen-year-old Lucy Chant, who carries about 20 pounds in her backpack, tries to always make sure she’s carrying it the right way.

“It’s not normal at first, kind of, but once you like put in the time and stuff you definitely feel a difference,” Lucy said.

Girls were significantly more likely to report back pain related to their backpacks than boys. The obvious solution is not carrying so much or switching to something that you can roll, like a carry-on bag used for traveling.

Stephanie Stahl