Journal of Health and Safety at Work

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Introduction: Work-related musculoskeleta ldisorders (WMSDs) of upperlimbs (UL)in the last 35 years have become extremely widespread, reaching epidemiclevels, inalladv ancedindustrializedcountries. They are considered the main cause of disability, time off work, and requests for healthcare

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Method and Materials: For detailed risk assessment, ISO -11228-3 is the preferred method. It is recommended for the specific purposes of ISO -11228-3(2007) because, given the knowledge at the time of publication, it considers all the relevant risk factors, is also applicable to “multitask jobs”, and provides criteria - based on extensive epidemiological data - for forecasting the occurrence of UL-WMSD (upper limb work-related musculoskeletal disorders) in exposed working populations. In this method is the ratio between the number of actual technical actions, ATA, carried out during a work shift and the number of reference technical actions, RTA, for each upper limb, specifically determined in the scenario under examination.

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Results: Results shown in 4 workstations include 35 task in an automotive industry. One of them is red and another’s are green.

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Conclusion: This method is suitable, quickly and very easy to use for assessment of ergonomics situation in work.

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Introduction: In last decades, due to the increase in the number of VDT works prevalence of musculoskeletal disorders has increased among users. One of the main risk factors for those problems might be related to the computer keyboards. Keyboards might lead to these problems, in different ways. Keyboard geometry is one of the main ways. As a result, the various types and shapes of personal computer keyboards have designed in order to provide a neutral or relaxed posture in the wrist and forearm areas. Slanted, sloped and tilted keyboards are the most important alternative keyboard designs for this mean.

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Material and Method: In this paper, with a systematic approach, related studies were searched in authentic databases and finally eleven studies met to our inclusion criteria for review.

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Result: findings in different studies showed that alternative keyboards clearly can provide an ergonomic neutral posture for the wrist and forearm. As a specific objective in the study, it was found that the best keyboard, to form an ideal posture for the wrist and forearm is ‘NIOSH keyboard‘ because of its ergonomic design.

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Conclusion: Considering the positive effect of the alternative keyboards on the wrist and forearm postures, it is concluded that use of the alternative keyboards can decrease risk factors related to the wrist and forearm postures. Results can be applied by personal computer users, computer designers, occupational hygienists and ergonomists.

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Introduction: Working with a computer and workplace conditions expose people to risk factors of musculoskeletal disorders (MSDs). This study aimed to assess posture, examine MSDs, and determine, weigh and prioritize the risk factors among computer users by a neural network algorithm. 
Material and Methods: This descriptive-analytical cross-sectional study was conducted in six phases on computer users in 2019. The status of MSDs was determined via Nordic musculoskeletal questionnaire (NMQ). The factors affecting these disorders were determined by the ROSA method, and then these factors were weighed by the neural network algorithm. The data were analyzed in IBM SPSS Modeler.
Results: The mean age and work experience of the users were 34 ± 6.9 and 1.5 ± 0.7 years, respectively. Most of years were observed at the lower back, neck, and upper back, respectively. The final mean scores of the chair, telephone-monitor, and mouse-keyboard were 3.7 ± 1, 3.6 ± 1.1, and 3.65 ± 1.2, respectively and the final mean score of ROSA was 4.4 ± 0.9. The greatest correlation with the ROSA score was observed in chair (R2 = 0.46), followed by telephone-monitor (R2 = 0.43), and mouse-keyboard (R2 = 0.42). The highest predictor importance of the effective factors based on the neural network algorithm prioritization belonged to the chair (48%), followed by telephone-monitor (28%) and mouse-keyboard (24%). The accuracy of the neural network algorithm in examining the effect of factors on musculoskeletal disorders was 98% based on the ROSA score.
Conclusion: Factors affecting years due to working with computers are the chair, telephone-monitor, and mouse-keyboard, respectively, as prioritized by the neural network algorithm. These disorders can be prevented by ergonomic modification of users’ chairs and correct placement of the monitor and telephone.

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Introduction: Musculoskeletal disorders (MSDs) have a multifactorial nature. Biomechanical factors are one of the most important factors. Consequently, the precise identification of effective factors plays a significant role in controlling and preventing these disorders. Therefore, the current study aimed to identify the awkward upper body postures and their effect on the prevalence of MSDs in office workers in both women and men groups by objective methods.
Material and Methods: In this cross-sectional study, the participants were 36 office workers (18 women and 18 men). The prevalence of musculoskeletal discomfort was evaluated using the Nordic questionnaire. The upper limbs posture, including the back, neck, and wrists, was evaluated continuously with an electronic inclinometer and an electrogoniometer for 30 min, followed by analyzing the collected data.
Results: The results revealed that the highest prevalence of musculoskeletal symptoms in both gender groups was in the neck (58.33%), trunk (52.77%), and wrist (47.22%), respectively. The results disclosed that the median trunk and neck flexion in both groups is over 20° and the posture angle in women is higher than that of men (P<0.05). The results showed that pain and discomfort in the trunk and neck in both gender groups have a significant relationship with the median posture angle (P<0.05). Also, the wrist posture in both gender groups during work was in extension and static condition.
Conclusion: Based on the results of this study, the prevalence of disorders in women was higher than in men. Although the tasks performed in both groups were similar, the assessment of postures disclosed that women office workers had more awkward postures in the trunk and neck than men. In both groups, the prevalence of musculoskeletal discomfort had a significant relationship with awkward postures in the trunk and neck. According to the results of the current study, ergonomic interventions are recommended to reduce awkward postures and to prevent MSDs, particularly among women office workers.

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Introduction: Biomechanical risk factors, including wrist and elbow angle and standing and sitting position, are the primary factors affecting hand grip strength and perceived exertion. The interaction of these factors can include different effects on grip strength and perceived exertion. Therefore, the present study examines the interaction of varying wrist and elbow angles in sitting and standing postures on the variability of grip strength and perceived exertion.
Material and Methods: In the present study, 30 students (15 females, 15 males) aged 19-30 participated. The average grip strength was measured by a dynamometer for 12 different positions based on the angle of the wrist and elbow in both standing and sitting postures. Perceived exertion was also assessed using the Borg CR-10 scale for each setting. Data analysis was performed using SPSS 23. The Wilcoxon test was applied to compare perceived exertion between standing and sitting postures. Furthermore, a three-way ANOVA was performed to examine interactions between posture (standing/sitting), elbow, and wrist angles. Mauchly’s Sphericity Test was applied to confirm the ANOVA assumptions, and effect sizes for multivariate analysis were calculated (partial η2).
Results: In both sitting and standing postures, the highest average grip strength was observed at a 0-degree wrist angle with a 90-degree elbow angle (standing: 28.6 ± 10.8, sitting 25.8 ± 9.8), while the lowest average grip strength was recorded at full wrist extension with a 0-degree elbow angle (standing: 19.3 ± 6.5, sitting 17.9 ± 6.9). In all three elbow angles examined (0°, 60°, and 90°), the highest value of perceived exertion was recorded in the full extension of the wrist. The changes in the grip strength at different angles were the same for sitting and standing postures, yet the hand grip strength was higher in the standing than the sitting posture (P-value<0.001). The effect of each of the studied factors (sitting and standing postures, wrist angle, and elbow angle) alone on hand grip strength and perceived exertion was deemed to be significant (P-value<0.001). Regarding the two-way interactions of the research variables, the interaction effect of elbow and wrist angles on grip strength (partial η2=0.09, P-value=0.015) and perceived exertion was significant (partial η2=0.08, P-value=0.06). Furthermore, findings indicated that the wrist angle had a more pronounced effect on the value of the perceived exertion (partial η2=0.31, P-value<0.001).