Effects of load carriage on adolescent spinal posture

Pao Yue-kong Library Electronic Theses Database

Effects of load carriage on adolescent spinal posture


Author: Choi, Wai-chong Susanna
Title: Effects of load carriage on adolescent spinal posture
Degree: M.Sc.
Year: 2007
Subject: Hong Kong Polytechnic University -- Dissertations.
Spine -- Wounds and injuries.
Posture disorders.
Department: Dept. of Health Technology and Informatics
Pages: ix, 83 leaves : ill. (some col.) ; 31 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2090231
URI: http://theses.lib.polyu.edu.hk/handle/200/3107
Abstract: Although no direct linkage between low back disorders and heavy backpacks, many evidences have shown carrying heavy backpacks may be related to low back disorders in adolescence. However, the information of the change of spinal curvature is critically limited among studies with various methodologies and measurements in existing literature. The aim of this study is therefore to determine the local changes in spinal curvature and spinal repositioning consistency of adolescent carrying a loaded backpack. The spinal curvature and repositioning consistency were measured for different load placements (backpack centered at T7, T12 or L3) at 15% of body weight or unloaded condition in a group of 10 normal adolescent boys (14-16 years). Nine reflective markers were attached to external occipital tuberosity, chin, C7, T2, T5, T7, T12, L3 and S1. A motion analysis system (Vicon 370E, Oxford Metrics, Oxford, UK) with six cameras was used for recording the standing posture. Postural angles of the spinal curvature were calculated between three adjacent markers (e.g., T2-T5-T7). Six repetitions of the posture were recorded for 3 seconds in each condition, while the standard deviation of the six repeated recordings was calculated as the repositioning consistency. The spinal curvature and repositioning consistency at each spinal level were analyzed by one-way repeated measures ANOVA with different center of gravity positions of backpack. Significant spinal curvature changes were observed which included a greater head on trunk extension (EO-CH-C7, CH-C7-T2) accompanied with greater thoracic kyphosis (T5-T7-T12) plus greater trunk forward inclination (L3-S1-Horizon) in all three load placement conditions. Post hoc comparisons showed the changes in curvature and posture of the extension of head/neck on trunk (EO-CH-C7) was significantly greater while carrying backpack centered at T7 than at T12. For the repositioning consistency, there was no significance in overall effect of the center of gravity of the backpack at three tested levels of the spine. However, in neck and upper thoracic region, better repositioning consistency was observed at T12 than at L3; at thoracolumbar region, better repositioning consistency at T12 than at L3 and during unloaded condition and also at thoracic region better repositioning consistency during unloaded condition when compared to at L3. The result of this study did not recommend placing the centre of gravity of the backpack as high as T7 in view of leading to greater neck extension than lower load placements. The change in repositioning consistency was not conclusive and might not be sufficient to determine appropriate load placement. Further investigation of the repositioning consistency of spine in relation to the posture adopted, while carrying backpack, might give more determinable information concerning the safety guidelines for adolescent backpack users.

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