Iranian Journal of Ergonomics

Introduction: The prevalence of work-related musculoskeletal disorders in computer users is high. The purpose of this study was to evaluate ergonomic assessment musculoskeletal disorders risk in computer users determine the effect of an eight-week corrective exercises program on reduction of musculoskeletal pain.

Material and Methods: In the first phase of the study, RULA technique and Nordic questionnaires were used to evaluate postures and musculoskeletal disorders of 84 computer users of Tuyserkan administrations. In the next phase, 30 individuals for participating in a corrective exercises program intervention divided into two groups namely, experimental (n=15) and the controls (n=15). Subjects were re-evaluated after period of eight weeks. Data was analyzed using independent and dependent t-tests.

Results: The overall prevalence of pain was seen in neck, lumbar, shoulders, back, carpal and hand, elbow respectively. In posture analysis, 61.3 and 53.6 percent of subjects were in action level of 2 in left and right limbs respectively, 32.2 and 44.1 percent of subjects were in action level of 3 and 2.4 percent in level of 4 in right side. After the corrective exercise intervention, there was 38.3% significantly reduction pain for upper limbs (p=0.001) and 38.7% for lower limbs (p=0.006).

Conclusion: This study showed that frequency of musculoskeletal problems in neck, lumbar, shoulders, back, wrist was generally high among our subjects, and selected corrective exercises could reduce the risk level and pain.

Introduction: Today, computers are widely used in many homes and workplaces. The relationship between computer use and musculoskeletal disorders in the neck and upper extremities has been well documented. Muscle fatigue in the shoulder and arm regions is one of the most frequently reported problems in computer users. Supporting the upper extremities has been suggested as a way to reduce the static load on upper body muscles while using a keyboard. The purpose of this study was to determine the effect of elbow and forearm support on upper trapezius muscle fatigue while typing.

Materials and Methods: Eight students of Bu-Ali Sina University (Hamadan, Iran) participated in this quasi-experimental study. The surface electromyography activity of the upper trapezius muscle of the dominant side was recorded in three positions, namely without elbow support, elbow support with the table, and elbow support with a pad while typing. The muscle fatigue index for the three typing positions was calculated based on the median frequency slope of the raw electromyography signals. Repeated measures analysis of variance (ANOVA) was employed for statistical analyses.

Results: Median frequency slope decreased significantly in elbow support with the table in comparison with non-support position (p = 0.04). There were no significant differences between elbow support with a pad and other two positions.

Conclusion: These results suggested elbow support as a mechanism to delay trapezius muscle fatigue and thus increase task efficiency. More research is required to determine the advantages or disadvantages of using different pads.

Background: The aim of this study was to investigate the effect of the heel wedges on the electromyography activities of the selected left and right lower back muscles during load lifting.
Methods: A total of 17 male subjects voluntarily participated in this quasi-experimental study. The selected subjects lifted a box, weighing 10% of their body weight, above the height of their hip joint, descending as far as the thigh, parallel to the ground, and then ascending to the starting position. The above task was performed nine times in two conditions, including with and without the heel wedges. Using the ME6000 electromyography system, the activity level variables were normalized and the median frequencies of the erector spinae (ES) and the multifidus (MU) muscles were recorded. The subjects also held the box for 30 s in the standing position with stretched hands. The paired t-test was used for the data analysis.
Results: The results showed that during static load lifting using the heel wedge, the median frequency of the right ES muscle changed significantly (P<0.05). Also during dynamic load lifting using the heel wedge, the activities of the left and the right ES muscles as well as the left MU muscle decreased significantly (P<0.05). However, no significant differences between the two conditions were observed for the other variables (P>0.05).
Conclusion: During such occupational tasks, a decrease in the activities of the selected lower back muscles with the heel wedge might result in a delay in the onset of muscle fatigue. The above findings might be used in the design of shoes, suitable for the work environments. However, further investigations are needed in this area in order to provide more accurate results.
 

Background and Objectives: Using anthropometric characteristics in the ergonomic design of workstations can be useful in the prevention and reduction of musculoskeletal discomfort and in office-work environments. The purpose of this study was to determine the anthropometric dimensions of Hormozgan province gas department staff to design desks and chairs for computer work based workstations.
Methods: This is a descriptive-analytical study for measuring 36 anthropometric variables of 121 Hormozgan province gas company staff selected by cluster random method. After collecting anthropometric data considering ergonomic design criteria, dimensions of desk and office chairs are designed.
Results: Participants were 80.2% male and 19.8% female with a mean age of 35.11 and a standard deviation of 6.6 between 25 and 59 years. The mean and standard deviation of height measured was 170.7 and 8.06 cm, respectively. Anthropometric results are shown separately by gender and percentile in the tables. Dimensions of chair and office desk are designed based on obtained data.
Conclusion: The presented anthropometric desks can be used in future studies and designs. Also, the dimensional characteristics of the furniture provided can be a practical guide for designing and manufacturing office workstations.