The effect of weight and duration of carrying backpack on forward head, kyphoses and lordoses in 14-18 year-old girls

In recent years, the weight of school backpack has become a growing concern and carrying the heavy backpack causes postural deformity. The aim of this study was to investigate the effect weight and duration of carrying backpacks on forward head, kyphoses and lordoses in 14-18 year-old girls.
In this prospective cohort study, 262 girls with the mean age 15.5±1.1 years, height 160±6 cm, weight 56.4±12.5 kg, backpack weight 3.98±1.3 kg, and duration of carrying 17.5±8.5 min were randomly selected. Then, 45 healthy girls (mean age, 15.8 years) were voluntarily selected and randomly divided into three groups based on basic measurements including the weight of backpack 3.5, 4.8 and 6.1 kg in 16, 21 and 27 minutes, walking on the treadmill with 1.6 meters per second. The forward head, kyphoses, and lordoses were measured before and after walking on treadmill.
Results showed that carrying backpacks more than 3.5 kg in 16 min increased the kyphoses angle (P=0.048). Moreover, the results showed that carrying backpacks with any weight significantly increased lumbar lordoses angles. However, no significant difference was observed in changes of forward head posture among the three groups.
Carrying heavy backpacks can increase kyphoses in girls. So, they should avoid carrying backpacks 6% heavier than their weight for more than 16 minutes.