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Background and aims: Cardiorespiratory capacity determines performance and productivity of daily jobs.Shoe production workers have heavy work load and musculoskeletal disorders is prevalent in this job. Investigation on the relationship between musculoskeletal disorders (MSDs) and job strain index (SI) and physical activity capability of shoe workers can help to reduce MSDs. Methods: This study was done on 235 shoe workers of Tehran Great Bazar. Cases of the study were categorized as having 5 roles of cutting, coating, preworking, gluing, and finishing (packaging, etc.). Nordic questionnair was used to assess the rate of musculoskeletal disorders, and Tuxworth & Shahnavaz step-test was used to find aerobic capacity, and the job strain index was used for ergonomic estimation. All data were analyzed using SPSS 20 software. Results: Between job strain and musculoskeletal disorders of end part of upper limbs (right side, left side), a significant relationship was found (p0.05). Conclusion: Musculoskeletal disorders of terminal part of upper organs (wrist, shoulder, and elbow) had strong correlation with job strain. Proper planning to reduce job strain and ergonomic training can reduce the risk of MSDs in terminal part of upper organs in shoe makers.

Background and aims: Evaluation of physical pressure during different working conditions is one of the important and applicable aspects of human factors engineering at industrial and construction environments. accurate calculation of physical pressure helps to improve working condition and status of workers. On of the challenges that experts faced with is the optimal assignment of human resources to the diverse tasks with respect to physical features of them. Methods: In this study, we chose 9 casual construction works to clarify our subject. Then we measure the pressure on lumbar area for all person during different position. In order to measuring the pressure, we assume average time that each person be in the different position in a single shift. After that we calculate work risks by means of Chaffin and Doisis model. At the next step in order to assign work to workers we use a linear programming model at which the cost of assignments is equal to work risks and the objective function is to minimize total work risk. Finally, by solving the model, best assignment is achieved. Results: Since we choose 5th percentiles to 95th percentiles anthropometric features, we find out that by increasing height and weight, the risk of all works increases too. However, by means of proposed method, we can make a decision that minimizes person’s work risk. Conclusion: Persons that has higher anthropometric features are not suitable for these kind of construction works and their risk increases up to 20% with respect to other ones. Also using mentioned method for decreasing total work risk among people is made benefits.

Backgrond and aims: Due to the rapid development of agricultural mechanization operations and the use of tractor as one of the most important agricultural machinery, focus on the health, ergonomic and safety working conditions of the tractor operators is a MUST. Methods: In this research the impact of BMI index and the leg angles of Iranian common tractors drivers on pain threshold reduction of Gastrocnemius muscle during clutching were investigated. Experiments were performed on two tractors including MF285 and MF399 models as two Iranian common tractors. The experiments were conducted by employing 30 drivers. Results: The results of data analysis showed that in MF285 tractor, the drivers with higher BMI index (within the normal range) and lower leg and thigh angles had small decrease of pain threshold. Consequently, these tractor drivers feel low level of stress in their Gastrocnemius muscle. The BMI index had the highest regression coefficient for all time intervals, during and after clutching of MF399 tractors. The impact of this variable for all time intervals on the reduction of pain threshold was the highest. So that one unit increase in BMI index would decrease the pain threshold reduction by 1, 0.89 and 0.69 N, respectively. The results of genetic algorithm showed that when the BMI index, knee, thigh and ankle angles are 24.75 kgm2, 101, 76 and 100 degrees, the decrease of pain threshold in Gastrocnemius muscle is reached to 0.016 Newton. For the MF399 tractor, when the BMI index, knee, thigh and ankle angles are 24.86, 130, 115 and 95 degrees, the decrease of pain threshold is reached to 0.316 Newton. Conclusion: The effect of BMI index was negative on the decrease of pain threshold for all time intervals, during and after clutching for both of tractors. The Gastrocnemius muscle of the drivers with higher BMI index is under less stress during clutching.

Background and aims : The most important factors that influence human performance are accuracy, speed and ability to perform the skills by individuals. Given the importance of human productivity in improving the production and quality, This study examines the impact of noise on error rate, speed and ability to perform the manual skills. Methods : This experimental study was conducted on 96 students. Sampling was conducted with a Randomized block design. Controlling exposure factors of sound intensity and duration of exposure, the accuracy and speed of performance of the test subjects were evaluated using Two-hand coordination test. Data was analyzed by SPSS18 software using descriptive and analytical statistical methods by ANCOVA repeated measure. Results : The results showed that the increasing of sound level pressure from 65 dBA to 95 dBA increased the work speed significantly (P

Background and aims The study is aimed at designing and testing a new ergonomic armrest that can address musculoskeletal problems among computer keyboard operators in Iran. Methods Twenty seven operators from an educational institute were selected as subjects. Direct observations and subjective assessment using Karlqvist et al.'s (1996) questionnaires were used to discover the weaknesses of their existing armrest. The existing armrest was replaced with the new armrest which allows height adjustment, and length, width and direction/rotation movements to suite various arm positions for keying and mousing tasks. Data on the hand and arm postures were collected and compared to common armrest. Results With the new armrest, results showed significant improvements in the postures of forearm, elbow, hand and wrist which facilitate easy access of the entire surface of keyboard and mouse. In addition, majority of the subjects were satisfied, in different aspects, with the use of the ergonomic armrest . Conclusion Because of its positive and dynamic features, the new armrest could well be replaced with the traditional and even forign ergonomic armrests attachable to the table. The new armrest do not disrupt the user’s job.

Background and Aims: Work related musculoskeletal disorders are common in midwiferypractice which requires extensive labor-intensive tasks. Therefore midwives are prone tomusculoskeletal disorders. This study aims at investigating the risk factors and musculoskeletalsymptoms among in midwives.Method: we conducted this cross-sectional study in Hamedan, western Iran. Active Midwives(n=134) were asked to complete the questionnaires (demographic and a version of the Nordicquestionnaire) if they had at least 1 year experience in practice and were not pregnant during theprevious year. 102 Midwives completed the questionnaires. Data were analysed by SPSS v.10software.Results: 66.7% of the Midwives reported some musculoskeletal symptoms, of whom 54% waswork related. The most common musculoskeletal symptoms were low back pain (50%), shouldersand wrists (46%). There were significant associations between musculoskeletal symptoms andmarital status (p< 0.001), duration of employment (p

Background and Aims:Holding body in a special posture and holding load simultanausly is astatic work . These postures are the biggest and most common problems in the work places.Work related musckloskeletal disorders (WRMSDs) are major occupational health problems inindustrial countries that are caused by a bad posture . One of the newest and usefull posture codingsystems that's used in a steel plant in finland for the first time is OWAS (Ovaco Working postureAnalysis System ).Method :This is a cross sectional study that is done in Mahyaman plant , in which 200 worker'spostures are evaluated and coding by OWAS method directly . Firstly , we prepared OWAS formsand went to that plant , then coding worker's postures and filled OWAS forms . Finally , we analyzecollected datas by OWAS software and the charts are prepared bye excel soft ware .Results :In 32 work phases (12.5%) worker's back had bending and twisting posture and in 7(2.7%) work phases they work with a bended knee .In 184 work phases (72.4%) , workers had a normal position and there is not any action needed butin 54 (21.2%) they had a stressful postures , so action is necessary soon .Conclusion: Bad postures cause musckloskeletal disorders , consequently low productivity inworkplaces .In this study we find out that 184 (72.4%) , 54 (21.2%) , 7 (2.7%) and 9 (3.5%) workers ,subsequently are paced in category 1,2,3 and 4 .It's good to point out that hazardouse postures are related to cooler coloring , 3 meter scissor andcleaning units in this factory .