A study from Korovessis et al. in Greece involving 1.252 students aged 12-18 from 7 high schools in Greece and making daily use of backpacks, confirms earlier evidence in concluding that backpack carrying, particularly asymmetrically, “results in a shift of the upper trunk and shoulder and cervical lordosis” and as a result “increased back pain in (the) school period and holidays.”
Summary points are:
a) A literature review including previous studies from Europe, the US and Australia showing that a large proportion of schoolchildren carry backpacks with loads exceeding a recommended maximum of 10% of their body weight, that there is an association between back pain and carrying backpacks to school, and that back pain at a young age is an important risk factor for back pain in adult life.
b) 55% of students carried backpacks asymmetrically, and this significantly increased the relative risk for dorsal pain (2.9 times) and low-back pain (5 times) compared with students carrying backpacks symmetrically over both shoulders. Students who carried backpacks asymmetrically were more than 4 times likely to suffer high-intensity pain compared with students who carry backpacks symmetrically.
c) Amongst all students, girls were 5.6 times more likely than boys to suffer from dorsal pain in the school period, and 4 times more likely than boys to suffer from high-intensity pain.

References:
Korovessis P, Koureas G et al. (2005) Backpacks, Back Pain, Sigittal Spinal Curves and Trunk Alignment in Adolescents: A Logistics and Multinomial Logistics Analysis, Spine 30:247-255.

For good public education information on backpack use, visit the website of the Ontario Chiropractic Association (www.chiropractic.on.ca) and see the Pack It Light, Wear It Right program