Iranian Journal of Ergonomics

Investigation of the Relationship of Sleep Quality, Sleepiness and Sickness Absence

Alireza Choobineh

Introduction: Sleep disorder is very common among employees and is considered as one of the crucial health problems. Sleep disorders have a negative impact on job performance. The present study was regarding the relationship of sleep quality, sleepiness and sickness absence.

Methods: This cross-sectional study was conducted on 400 employees of a gas company through random sampling. The study data were collected using the Pittsburg Sleep Quality Index (PSQI) and the Karolinska Sleepiness Scale (KSS). Mann-Whitney U test and Spearman’s correlation coefficient were applied for data analysis.

Results: While 43.2% of the participants enjoyed satisfactory sleep quality, 56.8% had unsatisfactory sleep quality. Statistical tests indicated a significant difference in sickness absence of the personnel with good and poor sleep qualities (P = 0.0001). Spearman’s correlation coefficient (ρ = 0.777) indicated a statistically significant correlation between sleepiness index and sickness absence (P = 0.0001).

Conclusions: The results showed a strong positive correlation in sleep quality, sleepiness index of the personnel and sickness absence; i.e. along with decline in sleep quality and incline in sleepiness, the personnel’s sickness absence increased.

Ergonomic Approaches and Challenges in Product Design

Iman Dianat

Introduction: The importance of product design has been dramatically increased in recent years due to economic considerations as well as changes in user preferences, policy making and legal needs. In response to this, and as one of the most influential branches in the field of product design (in terms of the fit between product and user), ergonomics has also been developed proportionally. The aim of this study was to review the most important considerations and different traditional and new approaches in product design as well as challenges and limitations in this regard.

Methods: A review was made of the relevant electronic databases including Ergonomics Abstracts, PubMed/Medline, Web of Science, Science Direct, Scopus and Google Scholar using the following keywords: product, design, ergonomic, design procedures and design approach. The search was limited to full text articles in the English language, published in peer reviewed journals between 1990 and 2015.

Results: Comparison of the traditional and new approaches in product design indicated that the new approaches helped designers to choose the best product model based on various aspects and a more detailed interaction between user and product. Ergonomic considerations in product design also include engineering and psychological aspects as well as taking into account abilities and limitations of both products and users, to find a good fit between user and product.

Conclusions: The findings suggest that the traditional approaches in product design alone may not anymore guarantee the success of a product in the market, particularly in universal scale and for a wide range of users. In other words, consideration of various technical (in terms of user-product interaction) and legal (environment, sustainability, cost benefit, etc.) aspects in new ergonomic approaches may be taken into account to improve the quality and success of the products in the global market. Ergonomists may encounter with some challenges to achieve this goal, but high-quality ergonomics services can be considered as an effective solution in this regard.

Study of Noise Reduction Rate of Hearing Protection Devices Based on Microphone in Real Ear (MIRE) Under Laboratory Conditions

Mohsen Aliabadi

Introduction: Nominal noise reduction rate of the earmuff manufacturers can be different compared with the actual attenuation rate. The present study aimed to determine the actual noise reduction rate of common hearing protection devices using microphone in real ear method.

Materials and Methods: In this study, five brands of common earmuffs used in Iranian industries were investigated on 30 subjects under laboratory conditions. Noise reduction rates of earmuffs were measured based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK, SV 102 model) equipped with a microphone SV 25 model. The earmuffs comfort was also assessed by the developed questionnaire.

Results: The results showed that the real noise reduction rates of the earmuffs were between 49% to 86% of nominal reduction rates. Moreover, the actual insertion losses were much negligible at low noise frequencies. The performances of earmuffs based on manufacturers were not statistically different (Pv> 0.05). Based on subjects’ comfort scores, comfort of ear muffs were within the acceptable range. The noise reduction rates of the different earmuffs of each model were not statistically different as well (Pv > 0.05).

Conclusions: Irregular use of earmuff can reduce the real attenuation of earmuff to lower than the minimum rate acquired in this study. Proper training and adequate supervision on proper use of earmuff can affect earmuff fitting along with increasing of real noise attenuation.

Validation of Researcher-Made Ergonomic Assessment Test for Freestyle Wrestling Skills

Mohsen Shojaatian

Introduction: According to the effectiveness and low cost of prevention, ergonomic assessment methods as a means to predict the potential occurrence of injury are being used. The aim of the present research was the assessment of validity and reliability of researcher-made ergonomic assessment test for freestyle wrestling skills.

Methods: In this research, according to the jobs ergonomic evaluation tests and wrestling pathology research, an ergonomic evaluation test for wrestling skills (WSEAtest) was designed. Content and face validity were proved by using the opinions of sports biomechanics and pathology experts, as well as physicians, physiotherapists, trainers and wrestlers of Freestyle national team. Furthermore, the test was performed on three skills in two different days by five examiners, using Kinovea software 0.8.15; also, intra- and inter-tester reliability were calculated. After the reliability and validity approval, WSEAtest was performed on video records of four selected skills of Iranian freestyle wrestlers in London 2012 Olympic games.

Results: The injury exposure in various parts of body, traumatic factors related to collisions and loads, and athlete and environment conditions were consistent with wrestling pathological research and confirmed the validity of the test results.

Conclusions: WSEAtest has acceptable validity and reliability; trainers, specialists, and sports therapists can use this test to assess traumatic factors and identify priorities for training and corrective exercises in different wrestling levels, and in various ages.

Efficacy Assessment of the Ergo-Feedback Software in Hospital Office Staff

Hamidreza Mokhtarinia

Introduction: In the recent decades, owing to the advancement of technology, most jobs and occupations require the use of computers. Lack of information about ergonomic conditions has resulted in various occupational injuries. Break time between work and doing exercise, help in reduction of musculoskeletal symptoms. The present study aimed to use a new ergo-feedback software and to assess its usability in office staff.

Methods: Thirty office staff participated in this study. In the first step, muscle-skeletal symptoms were checked by a body map checklist. Then, the Borg score was determined by the participants, initially and after one work day. The software was then run in their systems and they worked with it for about two weeks. After two weeks, the Borg scale was completed again and efficacy of the software was evaluated by the system usability scale (SUS). Data analysis was performed using descriptive statistics (mean and standard deviation) and Wilcoxon test. Statistical analysis was done by the SPSS software version 19.

Results: The results showed that there was a significant difference between the Borg score pre and post intervention (P > .05). The majority of the users were satisfied with the software with the SUS score showing about 82.25% satisfaction.

Conclusions: According to this study, office workers were satisfied with using this software and it can help reduce musculoskeletal symptoms during a prolonged time period.

Identification and Prioritization of the Factors Associated With Musculoskeletal Disorders in Nurses at a Specialized Hospital

mahnaz Saremi

Introduction: Nursing in hospitals, because of the nature of the work, is a job in which work-related musculoskeletal disorders are highly prevalent. The main cause of musculoskeletal disorder amongst nursing staff is the movement of patients. The aim of this study was to evaluate the risk of musculoskeletal disorders caused by movement of patients in nursing staff of a hospital affiliated with the Allah University of Medical Sciences.

Methods: This cross-sectional study was conducted on 325 nurses from 30 wards of Baqiyatallah hospital during summer 2015. Data were collected using demographic and Body map Musculoskeletal Disorders Questionnaires and PTAI index checklist. Statistical analysis was performed using the SPSS software version 16.

Results: Some musculoskeletal symptoms had been experienced during the last 12 months by 78.3% of the nursing personnel. The results indicated that PTAI index score was significantly associated with musculoskeletal disorders occurrence (P < 0.05)

Conclusions: According to the findings, PTAI is an appropriate tool for musculoskeletal disorders risk identification and assessment due to patient handling in nursing personnel.

The Effects of Job Stress on the Emersion of Employees' Organizational Citizenship Behavior in a Finance and Credit Institute in Mazandaran Province

hossein Samadi Miarkolaei

Introduction: Job stress is identified as imbalance between job needs and individual’s abilities and demands. Job stress has somatic, psychological and behavioral traumas, The main purpose of the present research was to investigate the effects of employees' job stress level on the emersion of organizational behavior amongst Mazandaran's SAMEN Finance and Credit Institute's subdivision employees.

Methods: In this correlation-descriptive study, 147 employees from SAMEN subdivisions of Mazandaran province were selected based on the census sampling method. Data were collected by using the job stress and organizational citizenship behavior standard questionnaire. Data were analyzed by the SPSS and LISREL software, and using descriptive statistics, Pearson’s correlation and Standard Error of the Mean (SEM).

Results: In the current study, there was a significant and inverse relationship between job stress and organizational citizenship behavior (R = -0.590, and P = 0.001). The results of structural equation modeling and path analysis showed that job stress and most of its components were good predictors of organizational citizenship behavior.

Conclusions: Recent research has demonstrated that job stress may increase employees-related problems. There is a relationship between job stress and organizational citizenship behavior, and attention to job stress level as a predictor of organizational citizenship behavior in employees is an essential issue.

Estimating the Maximum Aerobic Capacity of Fire Fighters Using The Step Test; A Case Study With Height Adjustable Steps

yousef babayi mesdaraghi

Introduction: Firefighting is amongst jobs that require high physical strength and high aerobic capacity. These are required because of the nature and the physical demands of the job. The maximum aerobic capacities of firefighters were investigated using the step test.

Methods: This cross-sectional descriptive-analytical study was conducted on 73 firefighters. At first, demographic information was collected by a questionnaire. Then, the step was built with adjustable height, for step testing, and using the Francis method, maximum aerobic capacity of the participants, was studied. The results of the questionnaire and step test were analyzed by the SPSS 16 software.

Results: maximum aerobic capacity of firefighters was calculated as 3.65 L/min and 47.4 mL/kgmin. Moreover, the results of statistical analysis revealed a significant relationship between body mass index and exercise, and maximum aerobic capacity (P ˂ 0.05). Also no significant relationship was found between maximum aerobic capacity, age, smoking and work-related fatigue (P > 0.05).

Conclusions: Studying the firefighters cardiorespiratory capacity, to reduce the probability of firefighters injuries is very important due to occupational sensitivity and having to perform difficult tasks under demanding circumstances. The results of this study showed that maximal oxygen uptake (vo2 max) and cardiopulmonary capacity of examined firefighters are greater than the minimum amount recommended by the international association of firefighters, which can be due to regular physical fitness programs conducted by the organization.