Lau Tsz Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 57-66). / Text in English; abstracts in English and Chinese. / Lau Tsz Chung. / Acknowledgement --- p.i / Abstract --- p.ii / Table of contents --- p.v / List of Figures --- p.viii / List of Tables --- p.x / Introduction --- p.1 / Background --- p.1 / Statement of Problem --- p.3 / Research Question --- p.4 / Significance of the Study --- p.4 / Theoretical Contribution --- p.4 / Practical Contribution --- p.5 / Review of Literature --- p.7 / Load carrying on Level Ground --- p.7 / Research Method Involved --- p.8 / Modified Gait Pattern During Load Carriage --- p.9 / Trunk Posture --- p.10 / Low Back Pain --- p.11 / Posture and Back Pain --- p.12 / Load Carrying Studies in Children --- p.14 / Stair Walking --- p.15 / Compared with Level Walking --- p.15 / Temporal Characteristics --- p.17 / Kinematics Measurement --- p.18 / Stair Dimensions --- p.19 / Stair Walking with Load Carriage --- p.21 / Physiological Studies --- p.21 / Biomechanical Studies --- p.21 / Methodology --- p.24 / Design --- p.24 / Subject --- p.24 / Instrumentation --- p.25 / Motion Analysis System --- p.25 / School Bag --- p.25 / Experimental Set-up --- p.25 / Procedure --- p.26 / Term Definition --- p.27 / Data Analysis --- p.27 / Results --- p.29 / Ascending Stair --- p.29 / Posture --- p.29 / Effect on Load Weight --- p.29 / Effect on Load Carrying Method --- p.30 / Velocity --- p.30 / Parameters of Lower Extremities --- p.30 / Descending Stair --- p.31 / Posture --- p.31 / Effect on Load Weight --- p.31 / Effect on Load Carrying Method --- p.31 / Velocity --- p.32 / Parameters of Lower Extremities --- p.32 / Trend --- p.32 / Summary --- p.33 / Discussion --- p.35 / Ascending Stair --- p.35 / Posture --- p.35 / Different Load Weights --- p.35 / Different Carrying Methods --- p.39 / Velocity --- p.40 / Descending Stair --- p.42 / Posture --- p.42 / Velocity --- p.46 / Parameters of Lower Extremities --- p.47 / Trend --- p.48 / Back Pain --- p.49 / Recommended Carrying Load Method and Weight for Children --- p.50 / Limitations of the Study --- p.52 / Further Study --- p.53 / Conclusion --- p.56 / References --- p.57 / Appendix --- p.67 / Appendix A - The experimental Set-up --- p.67 / Appendix B - Subject Consent Form --- p.68 / Appendix C - Figures and Tables --- p.71

There is anecdotal and scientific evidence to suggest that schoolbag carriage is associated with musculoskeletal discomfort (MSD) and possibly long-term back pain. Thus schoolbag carriage is an area of concern for students, parents and both education and health professionals. A schoolbag weight limit of 10% of body weight (BW) is currently recommended. However, it is based on subjective observations rather than objective findings and does not consider other aspects of schoolbag carriage such as schoolbag design and adjustment or carriage patterns. Five studies were conducted in order to determine the effects on students' responses to schoolbag carriage of schoolbag design, adjustment, carriage duration and weight. Backpack design had a significant effect on reported musculoskeletal discomfort and choice of backpack. Schoolbag hip-belt and shoulder strap adjustment and weight significantly affected shoulder strap tension forces and shoulder interface pressure in simulated schoolbag carriage. Using activity monitoring, school students were found to spend approximately two hours carrying their schoolbags each day. This usually comprised 11-15 times per day of 8-9 minutes of carriage. Using this temporal pattern information, 16 boys (13-14 years) were exposed to a simulated school day using schoolbags weighing 0, 5, 10, 12.5 and 15% BW and an additional condition of 10% BW with tighter shoulder straps. Posture, rating of perceived exertion (RPE), muscular strain and reported ability to walk and balance were significantly affected when schoolbag load reached 10% BW. However, despite these findings, the magnitude of self reported muscular strain and MSD suggested that 15% BW may be too heavy for school students. Thus, 10% BW may be an appropriate upper schoolbag weight limit for a typical school day. Using a psychophysical approach the mean (standard deviation) maximum acceptable schoolbag weight (MASW) selected by 16 school boys (13-14 years) was 10.4(3.8) %BW. This finding agrees with the findings of the previous study and supports the current schoolbag weight recommendation of 10% BW. The results of the five studies can be used in developing schoolbag carrying guidelines to help reduce the prevalence of MSD amongst school students.