Numerous, heavy books are thrown into a backpack and heaved over an aching shoulder. At the desired destination, the pack is dropped until it is once again found on the shoulder — all a part of a long day’s cycle.

That’s a day in the life of a backpack. But what students may not realize is that this pack could be the source of their back and neck pains. According to the American Chiropractic Association, 80 percent of Americans will suffer from back pain sometime in their lifetime, which is partially due to backpacks.

John Chatellier, chiropractor D.C. of Burke Chiropractic, 1303 E. Lincoln Highway, said a main factor of back pain caused by backpacks comes from the way the backpack is worn.

“If you wear your backpack over one shoulder, it’s going to cause structural imbalance,” he said. “Eventually, it will put postural stress on your body and can lead to back pains and other problems.”

Freshman mathematics major Lisa Holliday agreed that two straps is the best way to go.

“Students should consider wearing two straps ‘cool’ because since it’s better for your back,” she said.

Kenneth Olson, a physical therapy instructor, said not only is wearing two straps better than one, but padded, wide straps also help reduce strain.

“A wider strap is better because there’s important nerves and blood vessels under the collarbone that can get damaged,” he said.

Material is another factor to consider when choosing a backpack, Olson said.

“Nylon is lighter than leather, so that is a good material to choose,” he said. “If your backpack is causing pain, change the type of backpack. Also, avoid exceeding carrying more than 15 to 20 percent of your body weight in your bag. If your back pack is too heavy, it causes you to lean forward, which causes strain on the neck.”

While minor injuries can be treated if caught early, avoiding stress on the spine now can prevent possible future problems, Chatellier said.

“In the long run, there can be serious back problems because your body adapts to the environment it’s exposed to,” he said.

Constant improper usage of backpacks can lead to a variety of musculoskeletal and organ problems, such as abnormal spinal curves (of which scoliosis is the most extreme example), degenerative disc disease and muscle and ligament damage.

Chatellier said uneven back alignment also can contribute to difficulties in everyday tasks.

“When you’re doing some type of physical activity, it can cause you to be more prone to getting injured,” he said.