Iranian Journal of Ergonomics

Introduction: Pilot performance investigation during multi-tasking operations requires a procedure, in which the parameters related to the desired scenario of the simulator are obtained in a systematic manner. The multi-attribute task battery (MATB-II) is a standard simulator of generic piloting tasks developed by national aeronautics and space administration (NASA).

Methods: Employing information theory concepts, baud rate generated in all subsystems of the MATB-II were calculated and then, a unique numerical index presenting an estimation of overall workload was extracted. In the next step, three tests with different levels of workload were conducted to examine the validity of the offered criteria. These tests were performed by a group of subjects on the role of human pilots, while recording their own experiences about perceived workload via NASA-TLX.

Results: The results confirmed that there were significant differences between averages of scores assigned by subjects to the total workload, for three levels of difficulty defined based on information theory (P-value < 0.001). This variable shows considerable growth from low to medium and from medium to high categories of workload level.

Conclusions: The proposed quantitative index is effective enough for determination of workload levels in the MATB-II simulator.

Introduction: Studies have shown that one of the factors affecting occupational injuries is employees’ awareness of work situation. Therefore, it is important to identify factors affecting situational awareness. The aim of this study was to investigate the role of fatigue and cognitive failures in predicting work situation awareness among employees.

Methods: This study was a cross-sectional study with a descriptive-correlational design. The sample consisted of 154 employees of the Tehran Pars Khodro Company in 2015, who was selected by stratified random sampling method and responded to questionnaires of fatigue from Chalder et al. (1993), cognitive failures from Broadbent et al. (1982) and work situation awareness of Sneddon et al. (2006). Data were analyzed using Pearson correlation coefficient and stepwise regression analysis.

Results: The results showed that there were significant relationships between fatigue, cognitive failures and work situation awareness (P < 0.01). Also, fatigue and cognitive failures predicted almost 14% and 25% of the variance of work situation awareness among employees, respectively (P < 0.05).

Conclusions: The reduction of employees’ cognitive and emotional capacity could reduce their awareness of work situation.

Introduction: Heavy load lifting or occupational and individual factors are effective hazard agents in the occurrence of musculoskeletal disorders. Therefore, the aim of the present study was investigating the correlation of musculoskeletal disorders with work ability index and allowable load lifting limit.

Methods: This analytical and cross-sectional study was conducted using census (n = 60) among the kitchen workers in Qazvin teaching hospitals in 2016. Data were collected through questionnaires including pain prevalence, work ability index and allowable load lifting limit. Data was analyzed by single and multiple regression logistic using SPSS 16 software.

Results: The highest prevalence was observed in the lower back (78.3%). Of the workers, 61.7% reported a good level of work ability index and 58.3% of the workplaces were in unsafe conditions of load handling. Unsafe condition alone increased the prevalence of shoulder and neck pain about 7 times and the lower back pain 4 times, and in interaction with other risk factors, the prevalence of neck and shoulder pains had 25 and 28 times increase, respectively. Also, subjects with good levels of ability compared to subjects with excellent levels of ability were 9 times more in exposure of musculoskeletal disorders.

Conclusions: Risk factors such as body mass index, work ability and allowable load lifting limit can affect the prevalence of musculoskeletal disorders. So, selection of subjects with good and excellent work ability levels and compliance with the load limit are the effective solutions in increasing the productivity and reducing musculoskeletal disorders among kitchen workers.

Introduction: Few studies were conducted to determine the effects of lighting on cognitive performance. However, they could not reach a decisive conclusion. This study investigated cognitive performance of university students exposed to different levels of lighting under laboratory conditions.

Methods: In this experimental study, 33 subjects (age range 19-26 years) performed cognitive tests. Participants were exposed to three levels of lighting (200, 500 and 1500lux) in laboratory conditions while performing CPT tests to investigate percentage of attention and reaction time machine that measures reaction time.

Results: The results of this study showed that the maximum percentage of attention (99.75%) belonged to lighting of 1500 (lux) and the minimum percentage of attention was related to 500(lux) (99.36%). statistical analysis showed significant differences in percentage of attention in different levels of lighting (P=0.004). In addition, results of data analysis showed that increase in intensity of  lighting can make a significant change in the average response time (P˂0.001), correct response (P=0.004), commission error (P=0.001) and omission error (P=0.017). With increasing the lighting intensity, reaction time has decreased. The reaction time showed significant differences  at all levels of lighting (P˂0.001)

Conclusion: According to the findings of this study, lighting causes a decrease in reaction time and increase in attention. Thus, the lighting should be taken into account while designing of job and tasks which need attention or reaction time.

Abstract:

Introduction: Work-related musculoskeletal disorders (WMSDs) occur when the pressure that applied to musculoskeletal tissue is/be more than tissue tolerant capabilities. This study aimed to assess the risk factors cause musculoskeletal disorders associated with manual tasks using ManTRA and conducted ergonomics intervention program(educational- engineering) among workers in the printing industry.

MethodS: In this interventional case-control study, 40 workers who performed manual tasks, ( 20 case group and 20 control group) were chosen and were investigated. Nordic Body Map was used to determine the intensity and position of pain in the Different part of the body.  ManTRA method was performed to evaluate cumulative scores in four regions of the body (wrist / hand / arm - shoulder / neck - back - lower limb) for each workers before and after the intervention. Data analysis was done using SPSS.

Results: Data analysis showed that mean intensity of  pain in the control group before and after intervention in the various regions of the body such as  head /neck (p=0.012), right shoulder/arm (p=0.012), left shoulder/arm(p=0.043), back (p=0.003), right hand / wrist (p=0.028), left hand / wrist (p=0.027), right knee/ hip (p=0.005), left knee/ hip (p=0.005), right leg (p=0.012) & left leg(p=0.028) were significant.Cumulative score was also significant in the body regions such as arm/wrist /hand (p=0.001) and shoulder /neck (p=0.001) before and after the interventional program.

Conclusion: On the basis of the findings of this study, it could be noted that the ergonomic interventional program was effective to reduce the intensity of pain in the various regions of the body and risk factors causing cumulative damage in the workplace.

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Introduction: In some occupations such as nursing, due to specific job circumstances, sleep quality is poor. Given the importance of sleep quality, this study examined the impact of sleep health education on sleep quality among nurses.

Methods: This was an interventional and quasi-experimental research. The study population included the nursing personnel serving at elected Lorestan university hospitals. Among them, 50 were randomly assigned to a control group and 50 were selected as the intervention group. Data collection was organized according to a questionnaire posing demographical questions as well as Pittsburgh Sleep Quality questionnaire. Training intervention for the intervention group was carried out. Consequently passing 45 days, both control and intervention groups were called out for questionnaire filling. Data analysis was conducted using SPSS software, independent t-test and McNemar’s test.

Results: The study results showed that after the intervention training, there was a significant difference in terms of the average sleep score among the personnel of nursing, and after the training intervention, the sleep status of the personnel got improved compared to those of the control group (P ≤ 0.05).

Conclusions: The study results showed that sleep quality-improving skills trainings had an important and decisive impact on the sleep quality of nursing personnel and holding educational courses in this field for personnel can be useful.

Introduction: Leptin, generated by the obesity gene, acts as an anti-obesity hormone that plays a key role in regulating weight. We aimed to investigate the effects of eight weeks of selected aerobic training on serum leptin levels, anthropometric indices and maximal oxygen consumption (VO2max) in obese men.

Methods: Twenty healthy elderly men were selected by convenience sampling method and were randomly assigned to control (n = 10) and experimental (n = 10) groups. The program training included 45 minutes per session, three times per week for eight weeks of participation in aerobic exercise classes with 55-60% HRR. Pre- and post-aerobic exercise, serum leptin levels, anthropometric indices and VO2max were evaluated. To make intra and intergroup comparisons, t-test for dependent and independent samples were used. For all statistical comparisons, the level of significance was set at P < 0.05.

Results: Eight weeks of aerobic exercise led to a significant increase of Vo2max (P = 0.01). The amount of leptin (P = 0.007), weight (P = 0.002), BMI (P = 0.003), body fat percentage (P = 0.002) and WHR (P = 0.013) in sedentary obese men in the experimental group significantly reduced. The variations of weight, BMI, BFP, WHR and Vo2max in the two groups had differences.

Conclusions: The results of this study showed that the selected aerobic training had a favorable influence on improvement of serum leptin levels and VO2max in obese men.

Introduction: A significant number of employees of any organization experience burnout, in many different countries. It is obvious that burnout prevention and mental health promotion play an important role in the improvement of the quality of services. One of the strategies that could be useful in reducing premature aging is deployment of a total ergonomics (ergonomics micro and macro). The main objective of this study was to investigate the relationship between variables considered in the context of total ergonomics and burnout.

Methods: The sample was selected from one of the hospitals in Yazd, including various departments with 506 employees. The sample size of 216 was determined according to Morgan. The data were collected through questionnaires and samples were selected through a stratified random sampling method.

Results: The results showed that moderate job burnout and perceived organizational support by the employees was lower than average, and there was a significant negative relationship between burnout and variables involved in comprehensive ergonomics. The study showed that demographic variables of burnout were effective on employees.

Conclusions: This study investigated burnout level, organizational support, organizational justice and physical environment. The reduction of Burnout was assessed by improved total ergonomic (macro and micro ergonomic) conditions. The results obtained in this study correspond with the results of various research studies. At the end of the study, based on the results, suggestions were made to reduce burnout.

Introduction: One of the most important issues in industries is accident. Various factors affect these events, one of which is individual features. This study aimed at investigating the role of human resource personality on human reliability in accident outbreaks using DISC behavioral approach modal in automotive industry.

Methods: This was a descriptive-analytical research. The relationship of person vulnerability with human personality with fallibility was investigated. In order to determine human personality disk standard model was used and to estimate the degree of human fallibility heart techniques were used. Then, the relationships of natural personality, human reconcilable dimensions, human reliability and fallibility were found. Also, the relationship of accident repetition with personality and human fallibility was determined. This research was conducted among 98 personnel of one of the biggest production units during 2013 to 2015.

Results: The results indicated that there was a high correlation in human personality and fallibility dimension with accidents outbreak. There was a significant relationship between persons with influential personality, inherent stability, adapted stability, adapted dutiful, and accident outbreak repetition.

Conclusions:  According to the results, the personality of individuals with high sensitivity in their job and less adaptation to changes made in work environment, has a higher possibility of accidents outbreaks. Perhaps, this issue is created because of the inconsistency between the management system that is ruling the industry of developing countries and personality features of those people.

Introduction: Metro driving is one of the newest jobs in Iran. Due to the lack of studies about train drivers’ workload, there is no comprehensive information about factors that effect workload. This study aimed at analyzing the factors that may effect driver workload, in order to recommend control measures.

Methods: In this mixed method study, data generation was done through field observations, document reviews, individual interviews, focus group interviews, and focus group discussions. In order to perform field data collection, the institute for occupational ergonomics and CCD Design and Ergonomics Ltd’s developed tools were used. Directed content analysis was used for qualitative data analysis.

Results: Overall, 65 factors were extracted as the factors that may effect driver workload. The extracted factors were drawn on a fishbone diagram, over 8 categories, including management, supervision and organizational climate, infrastructure, job design, journey, and environmental as distal factors and time pressure, information exchanges, and individual factors as proximal factors.

Conclusions: Some of the distal factors are the nature of an urban transport system, so the only amendment is compensatory programs, and some of them could be resolved by long-term plans. Workload of train drivers could be reduced with a focus on the proximal factors in the short-term, and the distal factors in the long-term.

Introduction: Application and correct interpretation of the 6-minute walk test (6MWT) in medical, therapeutic, and exercise settings requires normal values of the 6MWT. The aim of this study was to develop and cross-validate the 6MWT prediction equation in Iranian healthy children and adolescent males.
Methods: The 6MWT and anthropometric variables were measured in 391 males (8 to 17 years old) with standard methods. Pearson correlation was used to assess the relationship between distances walked in the 6MWT and independent variables. Multiple regression analysis was used to design 6MWT prediction equation from dependent variables. Furthermore, accuracy of the present 6MWT prediction equation was cross-validated.
Results: Significant correlation was found between distances walked in the 6MWT and anthropometric characteristics (P < 0.001). Multiple stepwise regression reviled that age and Body Mass Index (BMI) could explain 63% of the variability of 6MWT in children and adolescent males (r²= 0.627, SEE= 36 m, P < 0.001). Accuracy of native 6MWT prediction equation was approved by good correlation between measured and predicted distance walked in the 6MWT (r² = 0.79, P < 0.001).
Conclusions: This is the first study on the development of native 6MWD reference values. With application of this 6MWD prediction equation, physicians, physical therapists, and fitness coaches could receive correct feedback of pharmacological, rehabilitation, and exercise interventions.

Introduction: Psychosocial factors and fatigue are significant factors in nurses’ performance. Since the relationship between psychosocial factors and fatigue has been rarely studied, the aim of this study was investigating the relationship between psychosocial work factors and fatigue among nurses.
Method: In this cross-sectional study, 270 nurses from hospitals of Urmia University of Medical Sciences randomly participated. The Job Content Questionnaire and Swedish Occupational Fatigue Inventory were used for data collection. Pearson’s correlation coefficient and Structural Equation Modeling were used for data analysis.
Results: The mean (SD) of control was 66.32 (7.36), psychological job demand 35.47 (3.68), social support 22.31 (2.64), physical job demand 15.22 (2.18), and job insecurity 8.72 (4.06). Control and social support dimensions had low levels. Moreover, psychological and physical job demand had high levels, which indicates a high stress level. According to the results, psychological and physical job demand had a significant relationship with all dimensions of fatigue (P < 0.001).
Conclusions: The majority of nurses were exposed to high levels of job stress. Among psychosocial factors, physical demand was identified as the most effective factor on fatigue. Any comprehensive interventional program regarding psychosocial work factor in order to reduce job stress and fatigue can improve health care quality and also prevent medical errors.
 

Introduction: Different studies around the world have shown that Work-Related Musculoskeletal Disorders (WMSDs) are the causes of lost time, absenteeism, and disability. The purpose of this study was to investigate the prevalence rate of musculoskeletal disorders (WMSDs) and to evaluate their ergonomic risk factors and determine the effect of ergonomic intervention on awkward postures among workers of Saipa Diesel Truck manufacturing plants.
Methods: This interventional study (Before-after) was conducted on 130 workers of 2 largest truck-manufacturing plants in Iran. The prevalence rate of MSDs and ergonomic risk factors was assessed by valid and reliable translated Body Map Questionnaire (BM) and Quick Exposure Check (QEC) method, respectively.
Results: According to Body Map results, 87.5% of participants had MSDs at least in one of their eleven body regions during the previous year, before study. The highest prevalence rate of MSDs was observed in lower back (51.5%) and foot area (18.5%). Chi square test revealed that the prevalence rate of MSDs was higher among those with higher QEC risk level (P < 0.001). Results also indicated the significant effect of ergonomic interventions on reducing the prevalence rate of MSDs and QEC risk level (P < 0.001).
Conclusions: This study showed that the prevalence rate of MSDs and QEC risk levels among workers was significantly high. Therefore, it can be mentioned that the need for early ergonomic interventions is felt in all industrial units of these truck-manufacturing plants.

Introduction: Lighting affects many non-visual functions such as Circadian rhythm, alertness, core body temperature, hormone secretion and sleep. The aim of this study was to investigate the effects of lighting on human cognitive and mental performance.
Methods: In this systematic review, databases including ISI Web of Knowledge, Scopus, PubMed and Science Direct were searched to access the relevant studies. The search was performed using the keywords "Lighting" and "Illumination" and "Cognitive Performance", "Mental Performance", "Memory ", "Attention", and "Concentration" by title, keyword and abstracts of articles published in mentioned databases from 2010 to 2016.
Results: Lighting affects human cognitive performance in three areas of psycho-cognitive (visual comfort, visual perception, color recognition, identification of symbols, attention, working memory, learning, reaction time and brain function), biocognitive area (alertness, mood, vitality, subjective feelings, motivation, well-being and quality of sleep) and mental workload (amount of workload, psychological stress, and mental fatigue). The best light to regulate cognitive, biological (circadian rhythm) and mental processes is bright daylight in the morning with a short wavelength (wavelength 420-480 nm) and high intensity (1000lx).
Conclusions: Lighting design in addition to providing comfort and visual needs should provide the non-visual and cognitive needs such as attention, alertness, mood, sleep quality and decrease mental fatigue and eventually well-bing.

Introduction: Nurses as the most important part of human resources in the health service system are often faced with problems associated with shift work. The present study aimed to examine a mediating role of sleep quality in the relationship between workload and physical and mental health among nurses.
Methods: This cross-sectional study was conducted on 236 nurses working in three educational hospitals in Bojnord city. To collect data, the survey of shiftworkers (SOS) questionnaire was used. Data were analyzed using the structural equation modeling by AMOS-21 and SPSS 19 software packages. In addition, the Preacher and Hayes’ SPSS Macro program was used for testing mediation.
Results: The results showed that the proposed model fitted the data properly. Also, workload directly affected only physical health, and the quality of sleep had a mediator role in the relationship between workload and physical and mental health.
Conclusions: Sleep quality as an important variable can mediate the relationship between workload and physical and mental health in nurses. So, it is suggested that interventional interventions to improve the health of the staff be focused on adjusting and shifting job shifts and teaching the principles of sleep hygiene to them.
 

Introduction: Job motivation as one of the factors that affect the behavior of librarians can improve their performance. Considering that organizational culture is one of the factors influencing job motivation, the aim of this study was to identify dimensions of organizational culture that can affect job motivation of librarians in public libraries of Iran.
Methods: This qualitative study was conducted using content analysis. Using the purposive sampling, 19 people of librarians of public libraries in 10 provinces were interviewed using depth and semi-structured interviews. After extracting the primary codes, they classifyied into three dimmensions and eight components.
Results: Based on the results of this study, dimmensions of organizational culture, which can affect job motivation included knowledge-oriented and capability-oriented culture (professionalism and meritocracy, professional capability, use of technology, and organizational learning), independency culture (non-politicization in the library, and decentralization), and participatory and motivational leadership culture (participatory management, and motivational management).
 In view of nature and social roles of public libraries and broad impressive factors on them, these models have limitations to assess status of organizational culture in public libraries. So, it is necessary to identify dimensions and components of effective organizational culture in public libraries of Iran and then manage the organizational culture on the basis of this effective culture.
Conclusions: Dimensions and components of effective organizational culture resulted from this study can be used as an ideal model for managing organizational culture or efforts to rule these cultural components in the public library of Iran.

Background: Attention to the workstations of the employees and their quality of work life has become increasingly important due to the increased competition in the organizations. The present study aimed to investigate the relationship between the ergonomic situation of the workstations and musculoskeletal disorders with the quality of work life and demographic variables in the administrative staff of the Tehran Municipality. 
Methods: The present study was a descriptive and analytical one. The statistical population included a total of 600 persons, working in one of the regions in the Tehran Municipality. Of the 600 staff, a total of 255 were selected as the available sample group. The instruments consisted of the questionnaires, including the individual and occupational information, the Nordic questionnaire, the Walton Quality of work life, and the checklist of the ergonomic indices of the working environment for the administrative staff. In order to analyze the data, Student’s t-test and multiple regression analysis were used.
Results: In this study, the majority of the samples were females (56.9%) with a mean age of 33 years. A significant positive relationship was observed between all the ergonomic indices and the quality of work life. Significant correlations among the parameters such as age, education, sleeping at night, psychological conditions, musculoskeletal disorders of the neck, shoulder, and foot were observed simultaneously with the quality of work life. The quality of work life of an employee could be predicted through the musculoskeletal disorders and demographic variables but could not be predicted by the ergonomic indicators. 
Conclusion: In this study, a relationship existed between the ergonomic condition of the workstations and musculoskeletal disorders with the quality of work life and demographic variables. Therefore, the physical condition and the quality of the work life of the employees would be positively affected by the improvement of the ergonomic condition of the workstations. 

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.