Researchers from the University of San
Diego, California School of Medicine say those students also share a common
problem: low back pain due to overloaded backpacks.
The results of their research, published in
the July/August edition of the Journal of Pediatric Orthopaedics, correlated
pain associated with using a backpack with two main factors: the magnitude of
the backpack load and the manner by which children distribute the load over
their shoulders and back.
"The optimal position for wearing a
backpack is high on the upper-back, with straps over both shoulders," said Alan
Hargens, Ph.D., professor, Department of Orthopedic Surgery, University of California,
San Diego School of Medicine. "Kids who wear their backpacks in the more
'stylish' lower back position, or only use one strap, may suffer shoulder pain
and posture problems."
Previous research by Hargens' team
(Archives of Pediatric & Adolescent Medicine, December 2005) shows that
even in the high back position, pressure build-up under the straps could
occlude blood flow and that pressures were higher on the right shoulder than
This most recent study quantified the
pressure under backpack straps while children carried a typical range of loads
under varying conditions.
"What's interesting here is that, contrary to
popular belief, it's not just the weight of the backpack, but how it's
carried," said Chambers. "And, the pain generated is not just on the back. It
includes the pressure on the skin, which causes nerve pain similar to that
tingling sensation caused when a leg or arm falls asleep."
Ten healthy children (5 boys, 5 girls),
ages 12 to 14 years, wore a backpack loaded at 10, 20, and 30 percent body
weight (BW). The children carried the backpacks in two positions: low on the
back or high the on back and pressure sensors measured strap pressure on the
When walking with the backpack straps over
both shoulders, contact pressures were significantly greater in the low-back
position than in the high-back position. And regardless of carrying position,
contact pressures on the right shoulder were always higher than those on the
On average, children load their backpacks
with a weight equal to between 10 and 22 percent bodyweight. When the children
put on a loaded backpack, they attributed 46 percent of the loading pain to the
lower back and approximately 15 percent to the shoulders.
"It's possible that our subjects alter
their posture by elevating the right shoulder, thus increasing the contact
pressure on that shoulder," pointed out Hargens. "If those postures are
practiced over a long period of time, with more weight and pressure on one
shoulder, it may alter posture and produce prolonged pain. We need to study
Advice from researchers to parents and kids
is simple: when it is necessary to carry heavy backpacks, carry them in a
high-back position, using broad straps, to spread the load, and to minimize
point pressures. Wear backpacks above the hips and maximize contact between the
backpack straps and upper body. If the backpack has a waist-strap, use it.
"Following these recommendations may
require conscious effort from the kids, encouragement from parents, peers, and
school staff, until it becomes habitual," said Murthy. "Although professionals
and parents cannot often dictate what children should carry, it is important
for us to educate them so they carry the packs correctly."
Researchers agree this study supports the
standard set by the American Academy of Orthopedics which suggests children carry a backpack weighing no
more than 15 percent of their body weight.
"Parents also need to check what their
children are carrying. We found that quite often it's not just books and school
work that's weighing them down... but iPods and laptop computers and other things
they may not need to carry to school everyday," said Chambers.