Combat didn't cripple the soldier's arm. Before he ever deployed to Iraq, a 100-pound backpack damaged nerves in the 20-year-old soldier's right shoulder and impaired his dominant appendage.

Combat didn't cripple the soldier's arm. Before he ever deployed to Iraq, a 100-pound backpack damaged nerves in the 20-year-old soldier's right shoulder and impaired his dominant appendage.

"He couldn't raise his arm to comb his hair, shave on the right side of his face," says Medford Dr. Ben Branch, a physical rehabilitation physician who treated the soldier at a Chicago-area medical center for veterans.

"It actually happened during his boot camp," Branch adds.

Hardly believing that a backpack could cause such injury, Branch looked beyond the military to the community at large, particularly school-age children who carry belongings on their backs every day.

"The text books typically have gotten heavier and heavier," the doctor says. "I don't think it's something most parents even think about — or teachers, for that matter."

Branch's sources, namely the American Academy of Orthopedics and universities, offered some surprising statistics. Sixty-six percent of school nurses reported seeing students with pain or injury attributed to carrying backpacks. Backpacks belonging to 55 percent of students are heavier than the recommended 10 to 15 percent of the student's body weight. Ultimately, 60 percent of children will experience back pain by the time they reach 18.

"Because there were so many back-pain issues, I started looking into (whether) there a correlation," Branch says.

Visiting a Chicago-area elementary school, Branch weighed students' backpacks. The heaviest among the school's fourth-graders tipped the scales at 49 pounds, he recalls. Compound that weight with the inappropriate size of many backpacks and fashion trends that influence kids to wear them improperly, and the outcome could be injury, Branch says.

"It's cool to just wear one strap," he says. "That can be a real problem.

"They're more likely to have back pain " if they developed these bad habits."

Branch, new to Medford's Providence Medical Group Physiatry, presented his research this summer to fellow physicians with some prevention tips. In addition to keeping a backpack's weight under 15 percent of a student's body weight, the bag should be no larger than the length of the wearer's back, measured from the shoulders to the top of the waist. If possible, choose a backpack with a waist strap, as weight is distributed better through the hips. And load a backpack with the heaviest items first, so they rest closest to the body, Branch says.

Some bags are specifically designed to minimize the load on a person's back. Along with a group of physicians, Branch tested some models and found that the AirPack, with its air-filled straps and lumbar cushion, seemed to lighten a weight of 35 pounds.

Some educators have found other ways to lighten up their students. In Ashland, middle schoolers use textbooks that remain in the classroom, and their homework is not reliant on transferring textbooks to and from school, says Julie Di Chiro, superintendent of Ashland School District.

The district's block schedule at the middle and high schools also cuts back on the number of books needed for daily classes, Di Chiro says. Students have 90-minute classes, alternating subjects every other day. While the primary reason for a block schedule is in-depth instruction, the side benefits of carrying fewer books home and the two-day window to complete assignments are convenient arguments in favor of block scheduling, Di Chiro adds.

"It's a legitimate concern, though, when kids are carrying around that much weight," she says. "We try to encourage kids to use backpacks on wheels."

These rolling bags, "like little suitcases," already are popular with a number of students in the Southern Oregon Education Service District, says physical therapist Michael Friedl. When it comes to kids with disabilities, a heavy backpack can be a major obstacle to maintaining balance, Friedl says. But any student could be susceptible to backpack overload, he adds.

"There's a cumulative effect by the end of the year."