The Effect of Mental Workload on the Prevalence of Musculoskeletal Disorders (Case Study: Bandar Abbas Zinc Production Company)

Introduction: One of the effective factors in the occurrence of musculoskeletal disorders is the mismatch between the mental workload on the person and his abilities and limitations. Therefore, this study aimed to investigate the effect of mental workload on the prevalence of musculoskeletal disorders in Bandar Abbas Production Company. Method: This cross-sectional descriptive-analytical study was conducted in 2019. The data collection tools included demographic information questionnaires, Nordic musculoskeletal disorders, and NASA-TLX mental workload. The participants were 172 people who were identified using Cochran's formula and simple random sampling. The collected data were analyzed by SPSS25 software. Results: The results indicated that 76.74% of the subjects had musculoskeletal disorders. Most of disorders were reported in the low back (51.16%), knees (38.95%), and neck (23.84%). The mean score of mental workloads in Bandar Abbas Production Company in this study was high (66.67). Among the mental workload subscales, the effort subscale had the highest score (85.32) and the performance subscale had the lowest score (20.00). Statistical tests showed that there was a significant relationship between mental workload and the prevalence of musculoskeletal disorders. Conclusion: According to the findings of the study, there was a direct relationship between mental workload and the prevalence of musculoskeletal disorders. Therefore, measures should be taken to reduce the perceived mental and psychological load, such as reducing working hours, interrupting and resting between working, increasing the variety of working postures, and

Physical Welding Factors for Reclassified Welding Positions in Shipbuilding Assembly Process Based on Muscle Activity Measured by Surface Electromyography

Welding, a key technology in the shipbuilding industry, is mostly performed by hand, owing to the complex structure and shape of production blocks. This manual welding requires a variety of working postures, which have become an important determinant of the worker’s workload and, consequently, assembly man-hours. Currently, major shipyards calculate welding man-hours by reflecting the welding factor, which is defined as the working time consumed in the welding process. A set of welding factors is known to be based on the accumulated experience in shipyards, whereas the verification or derivation process for these factors is not disclosed or available. This study proposed a method for quantitatively calculating work difficulty for welding positions based on the working posture in a process where the posture acts as an important variable. Standard welding positions reflecting the actual welding work at shipyards were established. A physiological assessment method was used to propose the physical welding factor by analyzing the measured muscle activity. The validity of the proposed method was verified by comparing the results of a musculoskeletal simulation package and shipyard welding factors. The proposed method can be readily applied to other fields in which workers’ physical activities are involved.

Effect of Computer Keyboard Slope on Upper Limb Postures at Sitting and Standing ComputerWorkstations : A Pilot Study

A user’s posture at a computer workstation, especially wrist posture, is determined by the keyboard angle. Most commercially available computer keyboards have a built-in positive slope that requires the user to extend their wrist approximately 20° when typing. The purpose of this study is to find the negative keyboard angles that minimize wrist extension for both sitting and standing workstations. In this study, we compared upper limb working postures, including those of the wrist, elbow and shoulder, at 5 different keyboard angles between −16° and +6° in sitting and standing postures. Based on our results, we can conclude that the optimal range of keyboard slope is from −4° to −12° in sitting posture and −8° to −12° in the standing posture in terms of minimum wrist extension, typing performance, and user preference. We also propose a universal keyboard support design as an attachment to currently available keyboards.

Assessment of the Working Posture among Dental Students to Prevent Musculosk ent Musculoskeletal Disor eletal Disorders

Poor working posture among dental practitioners has been known to cause musculoskeletal disorders (MSDs), which are made worse by lengthy procedures and a lack of awareness about the proper working posture. Objectives: To assess the working posture of clinical dental students to determine if interventions were needed to reduce MSDs. Methods: The working postures of 225 clinical dental students were recorded and assessed within 10 minutes into procedures from March-December 2019, using the Rapid Upper Limb Assessment (RULA) method. The results were then statistically analysed using chi-square and Fisher’s exact tests. Results: Of the 225 students observed, 64 (28.4%; 95% CI: 23.1-35.7%) were classified as having RULA scores of 1-2 and 3-4, 141 (62.7%; 95% CI: 58.4- 65.7%) had RULA scores of 5-6 and 19 (8.4%; 95% CI:5.3-12.4%) had RULA scores of 7. Only one student had a RULA score of 1-2, where posture was considered acceptable. The working postures of the students in year 4 (P<0.001) were worse than those of the students in the other clinical years. No significant difference was observed concerning gender variance. Conclusion: Students’ working postures should be evaluated frequently, and other tools, for example, dental loupes, should be provided to help them maintain good working postures

Working posture analysis on oyster mushroom farmers using OWAS method in Lempake, Samarinda, East Kalimantan

A preliminary survey showed that oyster mushroom farmers in Lempake Samarinda experienced pain in several body segments, especially at their waist. It may be attributable to the working condition that requires non-ergonomic postures such as frequent awkward posture in sitting or standing position. Therefore, this paper aims to assess the working posture in oyster mushroom farmers. Ovako Working Posture Analysis System (OWAS) method was applied to measure the risk level of farmers' working posture. A total of ten activities were observed from the oyster mushroom cultivations' process in four cultivations in Lempake, Samarinda, Indonesia. Each activity was assessed using the OWAS category based on the position of the back, arms, legs, and load. The result showed that 10% of farmers' working posture was classified in the 4th risk level category, categorized as highly dangerous for the musculoskeletal system, so direct improvement was needed. Furthermore, 10% of working postures were classified in the 3rd risk level category, and 60% of working posture was in the 2nd risk level category, which is categorized as dangerous for the musculoskeletal system and could cause significant tension so that improvement in the future as needed. On the other hand, 20% of working posture was classified in the 1st category which was safe for the musculoskeletal system

Analisis Risiko Postur Kerja pada Pengoperasian Mesin Pengolah Sampah Plastik Creatics

Ketidaknyamanan dalam postur kerja dapat mengakibatkan berbagai permasalahan dalam bekerja. Musculoskeletal Disorders (MSDs) atau gangguan pada otot, sendi dan sistem syaraf merupakan permasalahan yang paling banyak terjadi akibat bekerja. Hal tersebut dapat mendatangkan kerugian, baik bagi pekerja maupun perusahaan. Salah satu penyebab musculoskeletal disorders adalah postur kerja yang tidak ergonomis yang dapat membahayakan keselamatan dan kesehatan pekerja. Tujuan penelitian ini adalah menganalisis postur kerja dalam mengoperasikan mesin pengolah sampah terintegrasi Creatics. Metode yang digunakan adalah adalah penyeberan kuesioner Nordic Body Map (NBM) untuk mendeteksi keluhan sakit pada bagian tubuh pekerja dan metode observasi Ovako Working Postures Analysis System (OWAS) untuk mendukung hasil kusioner NBM untuk menentukan risiko bahaya dari postur kerja. Hasil yang diperoleh adalah responden mengalami keluhan sakit pada kaki, lutut, paha, lengan, pinggang, lengan atas kanan, lengan bawah kanan, bahu kanan dan pinggang. Hal ini didukung oleh hasil penilaian dengan OWAS yang menunjukkan postur kerja masuk dalam kategori dua, yaitu berbahaya dan perlu perbaikan pada rancangan mesin Creatics di masa yang akan datang.

Performance of Small-Scale Sawmilling Operations: A Case Study on Time Consumption, Productivity and Main Ergonomics for a Manually Driven Bandsaw

Sawmilling operations represent one of the most important phases of the wood supply chain, because they connect the conversion flow of raw materials into finite products. In order to maintain a high volume of processed wood, sawmills usually adopt different processing strategies in terms of equipment and methods, which can increase the value or volume of the lumber produced from logs. In this study, the performance of small-scale sawmilling operations was monitored, whilst also evaluating the exposure of workers to harmful factors. An assessment of time consumption, productivity, and main ergonomics was conducted during the use of a manually driven bandsaw. In addition, the exposure to noise was investigated to complement the knowledge in this regard. The results indicated a rather high time utilization in productive tasks, which may come at the expense of exposure to noise and to poor working postures. The modelling approach resulted in statistically significant time consumption models for different phases (blade adjustment, effective sawing, returning, unloading lumber, and loading and fixing lumber). The exposure to noise was close to 92 dB (A) (8 h) and, therefore, the level of emitted noise is likely to depend on the condition of the used blades, species sawn and on the dimensional characteristics of the logs. In terms of ergonomic risks, the poorest postures were those related to tasks such as moving the logs, loading the logs, fixing the logs, rotating and removing the logs, as well as unloading the lumber.

Analysis of Postural Instability in the Upright Position on Narrow Platforms and the Interactions with Postural Constraints

Background: Loss of balance is a considerable risk factor for workers while using ladders, because they are required to maintain static postural balance on platforms of a restricted size. This study observed center of mass (CoM) and center of pressure (CoP) behaviors and evaluated the effects of the platform depth (anterior–posterior length) and working postures. Methods: Eleven male participants stood on four platforms with depths ranging from 6 to 15 cm and maintained their positions for 60 s while performing or not performing other tasks (object holding, upward viewing, or both simultaneously). The kinematics were analyzed on the sagittal plane based on the inverse pendulum model. Results: The absolute moving range for the CoP–CoM linearly increased with the decreasing platform depth, and the working postures affected the slopes of the linear fits. The relative range of CoP–CoM displacement on narrow platforms was highly correlated with the subjective sense of instability. Conclusions: Monitoring the CoP is effective for a better understanding and evaluation of static postural balance. This study’s findings contribute to improving the design of work equipment through the use of wider platforms that are robust against the effects of working postures.

Assessment of Posture Related Musculoskeletal Risk Levels in Restaurant Chefs using Rapid Entire Body Assessment (REBA)

Background: Objective To assess the level of risk in posture associated work related musculoskeletal disorders in restaurant chefs using Rapid Entire Body Assessment [REBA]. Method: 30 subjects were included. Out of 30 subjects, all of them were males. The Mean Age, Weight, Height and working hours were 19.57 years, 52.06 kg, 185.28 cms and 8.63 hours respectively. Postures using REBA score sheet were evaluated based on the most difficult work tasks (based on observation and interview), the posture that was sustained for a longer period of time. Result: Body posture was evaluated using REBA sheet and it can be concluded that the major areas susceptible to painful working postures were of the neck and the wrist positions having the most frequent risk reported. Followed by the upper arm and trunk position having moderate risk and the least frequent area involved were legs and lower arm position. Conclusion: The study concludes that most of the restaurant chef’s fall under moderate risk of musculoskeletal disorders and require intervention and awareness about postural correction exercises to prevent further musculoskeletal injuries. Key words: Restaurant chefs, Posture, Rapid Entire Body Assessment, Ergonomics, Musculoskeletal risk.