Musculoskeletal Disorders (Definition , Causes , Risk Factors , and Prevention): Part I .

are injuries in the musculoskeletal system which is also named as “repetitive motion injury”or “repetitive stress injury” or “overuse injury” [1]. These disorders are the most prevalent and costly injuries which effect on suffered people’ life. As MSDs are multifactorial injuries, implementing a multidimensional musculoskeletal health program may be effective [2]. MSDs can arise from a sudden exertion due to lifting a heavy object [3], arising from repetitive strain, from repeated exposure to force, vibration, or awkward posture [4]. MSDs can affect many different parts of the body including shoulders and extremities (arms, legs, feet, and hands) neck, and upper and lower back [5]. Carpal tunnel syndrome, back pain, tension neck syndrome, tendinitis , hand-arm vibration syndrome and epicondylitis, are types of MSDs [4].The development of Musculoskeletal Disorders: When a worker is exposed to MSD risk factors, they begin to fatigue which may outruns his/ her body’s recovery system that in turn may be resulted in musculoskeletal imbalance And finally over time, leading to musculoskeletal imbalance persists MSDs develop [6] MSDs can arise from the interaction of physical risk factors with ergonomic risk factors such as biomechanical load, heavy loads, repetitive motions or from static positions, repetitive heavy loading [7-8] , Individual factors like gender and obesity [8-9], psychological factors such as workplace stressors, high job demands, low social support, overall job strain or job dissatisfaction [10-14] .However, social, and occupational factors such as workplace design, standing, twisting or tension in the body, posture during work repeated motion, or forces needed to perform actions on the job and vibration exposure [4,15-16]. These risk factors can be broken up into two categories: workrelated risk factors as ergonomic risk factors and individual-related risk factors. Thus, the basic cause of MSDs is exposure to MSD risk factors – both work-related risk factors and individual-related risk factors should be considered in controlling MSDs [17].