university of tennesse health science center Memphis, Tennessee, United States
Introduction: Use of backpacks (BP) by students of all ages continues to increase and has brought about an influx of new health-related problems. Of particular interest are musculoskeletal injuries at the shoulder and lower back resulting from carrying heavy loads over extended periods of time [1-5]. The goal of this study was to make modifications to the modern day BP that would reduce these complications. Purpose: The purpose of this study was to design and validate a novel offloading ergonomic backpack (EBP) that transferred a portion of the shoulder and spine loads to the pelvic region (Fig. 1). A modern day two strap BP was used as the control device to determine the shoulder offloading capacity of the EBP. It was hypothesized that the EBP would significantly reduce strap tension and shoulder loads compared to the traditional BP.
Materials and
Methods: Five participants wore the EBP and a standard two strap BP under quiet (vertical) stance conditions. Strap tension and shoulder loads were measured twice for six bag weight conditions (0,2,5,7,9,11kg). Portable luggage scales were attached directly to the shoulder straps and configured to measure strap tension. Load sensors (loadsol, Novel Inc.) placed underneath the shoulder straps provided an estimate of the total force acting on the shoulders and transferred to the spine. One-way repeated measures ANOVA and Cohen’s d effect size were analyzed to determine differences between backpack designs for the different bag weight conditions.
Results, Conclusions, and Discussions: Results: The EBP had a large effect size and significant reduction (p < 0.05) in shoulder loads compared to a traditional BP for all bag weight conditions (Fig. 2A). Similarly, the EBP had a large effect size in reducing strap tension compared to the traditional two strap BP (Fig. 2B). Conclusions: A newly designed EBP was effective at transferring a significantly large portion of the shoulder and spine loads to the pelvic region, which could reduce the risk of musculoskeletal injury. References 1. Genitrini M, et al. (2022) Impact of Backpacks on Ergonomics: Biomechanical and Physiological Effects: A Narrative Review. Int J Environ Res Public Health. 19(11):6737. doi: 10.3390/ijerph19116737. 2. Barbosa, J. et al. (2021) Impact of Overloaded School Backpack: An Emerging Problem. The Open Sports Sciences Journal. 14:76-81. DOI: 10.2174/1875399X02114010076. 3. Toghroli, R., et al., (2021). Backpack improper use causes musculoskeletal injuries in adolescents: A systematic review. Journal of education and health promotion, 10, 237. https://doi.org/10.4103/jehp.jehp_306_20. 4. Rodriguez-Soto, AE et al. (2013). Effect of Load Carriage on Lumbar Spine Mechanics. Spine, Vol. 38(13): pp. 83-91. 5. Santos, P., et al., (2023). Modular Backpack Project for Children – An Ergodesign Approach. Advances in Design, Music and Arts II 25, 502-513. https://doi.org/10.1007/978-3-031-09659-4_37.
