ABILENE, Texas -

We've all heard the dangers of carrying heavy things, but what happens when our kids carry heavy backpacks for years?

At Abilene Christian High School, the students carry an average of a 7.6 pound backpack.

Dr. Ken Mansfield of Mansfield Chiropractic said to determine how much weight is too much is dependent on the size of the child.

Isaiah Avila, who is an 8th grader at ACHS, has a backpack that weighs 10 pounds.

"It's pretty heavy,” Avila said. “I wasn't expecting it to be that much, but I don't have any injuries or anything in my back. It just doesn't really bother me. I'm used to it after a while."

Mansfield said constantly carrying around too much weight on your back and shoulders, though, can cause damage.

"The main danger is the change of posture because of the weight that they carry," Mansfield said. "They do it long enough it could cause problems with the discs in their lower back and especially in their back."

Some schools don't require students to carry textbooks, but if your kids have to carry a backpack, Mansfield suggested watching to if your child's posture changes.

"If their backpack is too heavy, they're gonna see these postural changes, then they need to either change the strap length or preferably have them not wear the backpack at all," Mansfield said.