Iranian Journal of Ergonomics

Introduction: In the orthotic and prosthetic workshops, awkward postures, repetitive and continuously movements etc. are the risk factors of musculoskeletal disorders (MSDs). This study was conducted with the objective of ergonomic assessment of working conditions in these workshops.

Material and Methods: In this study all employed personnel of linorthotic and prosthetic production centers in Shiraz city participated (n=42).Data were collected using Nordic Musculoskeletal disorders Questionnaire (NMQ) and Ergonomic Risk Factor checklist (ERF)for assessment of working conditions .Data analysis was performed using SPSS software (Ver. 16).

Results: The means (SD) of age and job tenure (years) in employees studied were 37.26 (10.21) and 12.8 (9.39), respectively .The most prevalent MSDs symptoms were reported in lower back (42.9%), shoulder (40.5%) and knee (40.5%).Working condition assessment by ERF check list revealed that the means core of upper and lower region of body and also mean of total score were higher than acceptable limit (more than 7)..

Conclusion: In working conditions improvement, corrective measures and MSDs risk factors control in studied workers should be noted to risk factors in low back, shoulder and knee. The results of this study showed that ergonomic problems in orthotics and prosthetics clinics was related to "custom shoe making", "grinding and finishing", "filling plaster cast" and "positive cast rectification" tasks and ergonomic interventions to decrees and/or eliminate of awkward working posture needed corrections.

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: Musculoskeletal disorders are common in students and several causes may be considered for them. The aim of this study was to investigate the relationship between school furniture dimensions and trunk posture with musculoskeletal disorders in students of the sixth grade of elementary school in Karaj.
Methods: In this cross-sectional study, 346 boy students in sixth grade of elementary school in Karaj were selected. A flexible ruler was used to measure thoracic kyphosis and lumbar lordosis angles. A 50-centimeter metal ruler was used to record ergonomic and anthropometric data of the students. Spearman’s correlation test was run to analyze the collected data at the significant level of 0.05.
Results: The results showed that only 18%, 12% and 50% of desk height, seat depth and seat height measures were at normal ergonomic conditions, respectively. A negative significant correlation was observed between seat depth and total Nordic score (P<0.05).
Conclusion: It seems that school furniture dimensions in sixth grade boy students of elementary school in Karaj were not in acceptable condition. So, we suggest that ergonomics standardization of school furniture should be considered to prevent its possible consequences.