The effect of different backpack loads on spinal curvature in adolescent

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The effect of different backpack loads on spinal curvature in adolescent


Author: Leung, Tsz-yin Keith
Title: The effect of different backpack loads on spinal curvature in adolescent
Degree: M.Sc.
Year: 2006
Subject: Hong Kong Polytechnic University -- Dissertations.
Backpacking injuries.
Spine -- Wounds and injuries.
Department: Dept. of Health Technology and Informatics
Pages: xii, 93 leaves : ill. ; 30 cm.
Language: English
InnoPac Record:
Abstract: Backpack is a commonly used in students to bring textbook to school and the overweight of backpack in Hong Kong students was being indicated. Over 50 % of Hong Kong students whose backpack weight are over 10% of their body weight. However, the effect of a heavy backpack on spinal curvature was not clear on adolescents. Despite evidence linking backpack carriage and back pain, previous studies to examine the effects of backpack carriage have focused on changes in physical performance rather than the direct effects on the spine itself. The evidence on the loading effect of backpack on spinal posture is still not clear. This study was done to determine local changes in spinal curvature and spinal repositioning consistency of schoolboys carrying a loaded backpack. Fifteen male subjects between the ages of 15 and 16 participated in this study (mean age =15.2, SD=0.4). All the subjects should not have any history of back pain, spinal deformity, shoulder pain or neck pain and they were underwent a series of physical examination on spine by the investigator. The experiment was done using a motion analysis system to monitor the positions of reflective markers attached to the spine (External occipital tuberosity, chin, C7, T2, T5, T7, T12, L3, S1) during normal upright stance without a backpack and while carrying a specially adapted backpack loaded at 10%, 15% and 20% of each of the study participant's bodyweight. Six repeats of the posture were recorded at each load to obtain the mean spinal curvatures and repositioning consistencies. The angles of the spinal curvature were generated from each consecutive three coordinates which were calculated by a dot product mathematical formula. The standard deviations of the spinal angles from the six repeated trials represent the repositioning consistencies of spine. The obtained data were analysed by a repeated measures ANOVA. The result indicated that a significant flattening of the lumbar lordosis (p<0.05) and the upper thoracic kyphosis (p<0.05) was found with increasing backpack load. A significant extension of the neck lordosis (p<0.05) was shown when the backpack load appeared. It implied that the head position was more upright and the kyphosis of the upper thoracic became flat to compensate the changing of head position during increasing backpack load. Beside the spinal segment, the inclination of the whole trunk significantly increased (p<0.05) among all the experimental conditions. However, the results of the repositioning consistencies were not similar as the position changes. The significant decreases of repositioning consistencies on the lumbar region were demonstrated, started with 10% body weight (BW). When the backpack load increased to 20%BW, the repositioning consistencies were also decreased significantly on thoracic and thoraco-lumbar region (p<0.05). It implied that the instability of spinal posture shifted upward from lumbar to thoracic if the backpack load became heavy. However, the neck region and the trunk inclination did not have significant changes in the repositioning consistencies. The result concluded that the carriage of a loaded backpack caused immediate changes in spinal curvature and appeared to have a direct effect on the repositioning consistency. However, the changes in repositioning ability of spine might not be directly affected by the spinal curvature. The loading effect on spinal curvature will affect the stresses and strains on spinal tissues and may be related to the occurrence of lower back pain. Although backpack load induce the changes in spinal curvature was found, a potential risk of backpack loads could not be showed in this study. Furthermore, this study only looked into the immediate effect but the long term effect of backpack carriage might also be considered. Therefore, further studies on these aspects were recommended.

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