A model of the risk factors of work-related musculoskeletal disorder

Date of Publication


Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Industrial Engineering

Subject Categories

Operations Research, Systems Engineering and Industrial Engineering


Gokongwei College of Engineering


Industrial Engineering

Thesis Adviser

Rosemary Seva

Defense Panel Chair

Alma Maria Jennifer Gutierrez

Defense Panel Member

Jose Edgar Mutuc


Work-related musculoskeletal disorders have been affecting office workers since the 21st century. It contributes the feeling of pain in the muscles, tendons, joints, bones, ligaments, and nerves in the body. Due to this, the welfare of the workers is affected, and companies like ALGA who value their employees' work life aims to improve their welfare by determining which of the workstation design, occupational, and personal factors contribute to upper body WMSDs.

Based on previous studies, some of the factors that can contribute to upper body pain (neck, right and left shoulder, and upper and lower back) are related to computer workstation design factors and occupational factors. The current workstation was assessed with ergonomic tools such as glare, anthropometry, Rapid Office Strain Assessment (ROSA), postural analysis, and Cornell Musculoskeletal Discomfort Questionnaire (CMDQ). The result of the workstation assessment using Rapid Office Strain Assessment (ROSA) shows that the current workstation design used by the workers has a grand score of 8.18 which means that there is high risk of WMSD and workstation should be further assessed as soon as possible. The factors contributed to the high score are the chair (8.06), monitor and peripherals (6.82), and mouse and mouse and keyboard (6.79). Problems with these workstation design have a significant effect on upper body pain, specifically in the neck, right and left shoulder, and upper and lower back. This was confirmed by the CMDQ result where the highest complaints of discomforts of the participants are in their lower back (14,71%), upper back (11.20%), right shoulder (8.17%), neck (7.85%), and left shoulder (16.23%). Moreover, the workstation design factors that contributes to upper body pain are Keyboard Height, Monitor Height, Backrest Position, Monitor Distance, Monitor Position, and Keyboard Distance. The occupational factor is the Length of Years Working in the Company, Repetitive Motion of the Finger, Hands, and Wrist, and Job Demand (Quota). On the other hand, personal factors include Age, Anthropometry, and Gender.

Nonetheless, some of the factors was eliminated due to the limitations of the study such as the adjustability of the workstation and participant considerations. Moreover, due to the limited time to conduct the experiment with five independent factors, associative regression was perfom1ed to find which of the computer workstation design factors are significant. From the associative regression of the computer workstation design factors, the significant factors that were found to contribute to upper body pain were Backrest Position and Monitor Distance. Therefore, these were the computer workstation design factors that was included in the experiment.

The experimentation was done in the office of the claims department employees of ALGA. 15 claims agents were included in the experiment whose ages ranges from 20 to 35 years old and have experiences on upper body pains. The modified Cornell Musculoskeletal Discomfort Questionnaire was used as the response variable of the experiment and only three independent factors where tested in the study which are the Backrest Position, Monitor Distance, and Job Demand. Response Surface Methodology, specifically Box-Behnken Design, was used to analyze the results.

Experimentation was conducted to be able to create a model of the interactions between the workstation design, occupational, and personal factors. This would show which factor contributes significantly to WMSD and which factor is needed to be prioritized first. Moreover, the interactions between the computer workstation design, occupational, and personal factors that contributes to upper body pain can also be seen through experimentation and modelling the effect of changing the settings of Backrest Position, Monitor Distance, and Job Demand. Based on previous studies, these factors have relations to upper body pain. However, when combined, its effect is not known yet.

The result of the analysis shows that the significant predictors of upper body pain (neck, right and left shoulder, and upper and lower back) are the Backrest Position and Job Demand. The result of the Response Surface Methodology explained the relationship between upper body pains and significant predictors. Based on the findings, Backrest Position and Job Demand turned out to be the significant factors that contributes to upper body pain. Since the relationship between Backrest Position and CMDQ score is negative, this indicates that the larger the backrest angle is, the lower the CMDQ score, as the model aims to minimize CMDQ score. On the other hand, Job Demand is proportional with the CMDQ score, wherein if the Job Demand is low, the CMDQ score is also decreased, and vice versa. Additionally, since the estimated coefficient or beta of the Backrest Position is the highest among the factors, this means that computer workstation design factor should be prioritized. Moreover, this states that the first specific hypothesis of the study is proven true as the coefficient of the Backrest Position is greater than that of Job Demand. Meaning that the effect of the Backrest Position on the risk of WMSD is greater than the Job Demand.

Nonetheless, the other specific hypothesis of the study which states that the placement and position of the computer components have a higher contribution to the risk of WMSD than Job Demand was disproved by the result of the study. This can again be seen in the beta coefficient of both of these factors wherein Job Demand has higher beta coefficient than Monitor Distance. Furthermore, other workstation design factors, namely the Monitor Position, Keyboard Distance, and Keyboard Position turned out to be insignificant risk factors of upper body WMSD. Moreover, since Job Demand is also a significant factor, this factor can also be adjusted to minimize the upper body pains felt by the workers.

From the findings of the study, the recommended setting of the Backrest Position, Monitor Distance, and Job Demand was generated to minimize upper body pains of the workers. The recommended settings are reclined position (114 degrees), average Eye-Monitor Distance (60 cm), and lowest Job Demand (14 documents). Nonetheless, on peak days where Job Demand is inevitably high, the workers should have micro-breaks of every 40 to 60 minutes for them to stretch their muscles. This recommendation would not only benefit the claims department employees of ALGA as it can also be applied on different workstations that would allow the same settings of the workstation.

Abstract Format






Accession Number


Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall


Human engineering; Musculoskeletal system—Diseases—Prevention—Needs assessment; Occupational diseases

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