en Occupational and Industrial Health Occupational and Industrial Health پژوهشي Original Article <p dir="ltr"><span style="font-size:14px;"><span style="font-family: times new roman;"><strong>Background: </strong>Musculoskeletal disorders (MSDs) are among the most prevalent pains which could be ignited via material handling. Backpack wearers are among those who may carry heavy loads. Since MSDs mainly originate in school-aged children, students (as the largest group of backpack wearers) are considered more important. The purpose of this study is to design a backpack based on minimization of shearing force.<br> <strong>Methods</strong>: At first the relevant patents were investigated at national and international levels. Then the appropriate ones selected for optimizing. The main selection criterion was based on reduction of pressure on body. As an extra function we used a generator to produce electricity. The criterion for electricity generator selection was: 1) small dimension, 2) low weight, and 3) safe voltage.<br> <strong>Results</strong>: A suspending system used to eliminate shearing forces. Since a wearing backpack student is under the shearing force caused by walking, a spring system was used as a reducing device for shearing force. Physical spring calculation revealed that springs with stiffness coefficient equal to 588 was appropriate.<br> <strong>Conclusion</strong>: In comparison with existing designs, suggested backpack design can reduce forces on upper limb during handling the backpack<a name="_GoBack"></a></span></span>.</p> <p dir="ltr"></p> Backpack, Musculoskeletal disorders, Student, Suspending system 159 165 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-28-4&slc_lang=en&sid=1 Shirazeh Arghami arghami@zums.ac.ir 10031947532846009260 10031947532846009260 No Department of Occupational Health Engineering, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Mojtaba Moshayedi m.moshayedi110@yahoo.com 10031947532846009261 10031947532846009261 No Department of HSE Management, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Idin Rahim Ziad aidin_rahimziad@yahoo.com 10031947532846009262 10031947532846009262 Yes Department of Occupational Health Engineering, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran.