Journal of Health and Safety at Work

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Introduction: In Iran country, small enterprise with less than 10 workers comprise about %90 of all industries and 80% of working population. Noise, higher than the permissible level is among the hazardous agents, workers in these plants facing with. The aim of this study was to investigate the correlation between screening estimation and noise measurement in small plants.

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Material and Method: This cross-sectional study was conducted in 51 plants with less than 5 workers. Noise screening was done using screening from. Next, noise level was measured in all the plants by TES-1358 sound level meter and regular grid method. Data were analyzed using chi-square test and linear regression in SPSS version 16.

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Result: The mean (SD) scores of sound pressure level and screening form were 86.5 dBA (4.5) and 64.2 (9.4) in 51 understudy plants, respectively. According to the results of sound measurement, sound level in 34 plants (66.6%) exceeded the permissible level and in 17 plants (33.33%) was below the limit. The results of screening forms showed that 47 plants (92.16%) had permissible level of noise while noise in 4 (7.84%) was not in permissible level. Chi square test revealed no significant relationship between the results of the two methods, based on the permissible and impermissible limits (p-Value=0.288). Furthermore, according to the regression analysis, R2 was obtained 0.357.

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Conclusion: No correlation was shown between the results of the two methods used. Thus, it is recommended to change the parameters used in the noise screening form for small plants, with less than 5 workers.

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Introduction: Air health is an important environmental issue which has been endangered in recent years due to application of advanced technologies used for improving the financial welfare and relative prosperity of humans. Making use of pollution control systems and refinement methods are some general ways to control environmental pollution. Since several different techniques of control, each with its advantages and disadvantages are employed in order to mitigate the spread of air pollution, the aim of current study was to design a fuzzy multi-attribute decision making model to select the most appropriate air pollution control equipment in Mashhad Shargh Cement Company.
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Material and Method: After identifying the desired industry and also the production process, all factors affecting decision-making process including environmental factors, technical factors and economic factors were considered by utilizing Fuzzy Analytic Hierarchy Process method. Importance weight of these criteria was calculated and subsequently the priority of model choices were also determined using this approach.
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Result: Among main criteria of the model, economic criteria was identified as the most important factor influencing the selection of the type of air pollution control equipment, with the wight of 0.555. Environmental and technical factors with weighting of 0,286 and 0,159 also gained the next priorities, respectively. Final weights of Electro filter, Baghouse and Hybrid filter technologies were calculated 0.256, 0.415 and 0.329 in cement mill unit and 0.291, 0.374 and 0.334 in material grinding and furnace unit, respectively.
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Conclusion: Finally, the proposed model that is based on the Fuzzy Analytic Hierarchy Process indicates that the Baghouse Technique is the most appropriate technique for the purpose of dust filtration in major sources of air pollution spread in Shargh Cement Company.

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Introduction: Working in hot and inappropriate climate condition is one of the most common problems of occupational health which can lead to heat induced diseases and even death. Heat stress may impair the cognitive processes involved in decision-making and converting simple tasks to complex ones. The aim of present study was to assess selective attention and reaction time among workers in a casting unit of a car manufacturing industry and to investigate the effects of heat stress on mentioned variables.

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Material and Method: In this retrospective cohort study 70 workers from a hot industry were selected in two of exposed and control groups. First, demographic questionnaire was completed for each of the participants and noise and light were measured as the likely confounding factors. Stroop test 1, 2, and 3 were done before and during the work in order to determine the effects of heat on selective attention and reaction time. Besides,WBGT were measured at the ankle, waist, and head levels. Data were analyzed using SPSS software, version 18.

Result.: WBGT measurements showed that the mean WBGT were 33 and 16.7 for the exposed and not exposed groups, respectively. Moreover, no significant relationships were observed between test duration, reaction time, and number of errors in Stroop tests 1 and 2 and the level of heat (P-value<0.0001). However, the mentioned variables had a significant positive correlation with Stroop test 3. Additionally, for exposed group variables of test duration, reaction time, and number of errors in Stroop 3 were significantly higher than those of control group.

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Conclusion: According to the findings in present study, heat stress causes an increase in reaction time and a decrease in selective attention. Thus, heat can be assumed as a stressor in hot work environments and the heat should be taken into account while design of job and tasks which needed selective attention or reaction time.

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Introduction: Work-related accidents may cause damage to people, environment and lead to waste of time and money. Health, Safety and Environment Management System has been developed in order to reduce accidents. This study aimed to investigate the effect of implementation of this system on reduction of the accidents and its consequences and also on the safety performance indices in Kermanshah Petrochemical Company.

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Material and Method: In this study, records of accidents were collected by OSHA incident report form 301 over 4 years. Following, the mean annual accidents and its consequences and safety performance indices were calculated and reported. Then, using statistical analysis, the impacts of two years implementation of this system on the accidents and its consequences and safety performance indices were evaluated.

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Result: The results showed that the implementation of HSE system was significantly correlated with Frequency Severity Indicator, Accident Severity Rate, lost days, minor accidents and total incidents (P-value <0.05). Moreover, the values of these variables have been reduced after implementation of this system. However, the system did not influence the Accident Frequency Rate and disabling accidents (P-value> 0.05).

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Conclusion: The implementation of Health, Safety and the Environment Management System caused a reduction in accidents and its consequences and most of the safety performance indices in the entire process cycle of Kermanshah Petrochemical Company. Overall, safety condition has been improved considerably.

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Introduction: Quality of Work Life (QWL) is a new form of job satisfaction which involves ones feelings about all aspects of their job. The aim of this study was to assess the psychometric properties of the Persian version of WRQoL-2 questionnaire for use in the nursing community.

Material and Method: In this study, backward translation method was used in order to verify the linguistics stability. Then, the cross-sectional study was conducted among 270 nurses working in a hospital, affiliated to Tehran University of Medical Sciences. Reliability and construct validity was investigated using test-retest and factor analysis, respectively. In addition, discriminant validity was assessed by comparing QWL mean scores of nurses satisfied with their salary and those who were dissatisfied.

Result: Regarding the reliability, it was observed that the repeatability coefficient were at an acceptable level for all dimensions of the WRQoL-2questionnaire. According to factor analysis, six components were identified with some questions in different groups compared to the original questionnaire. Considering discriminant validity, all components, except Stress at Work, obtained P-value less than 0.05.

Conclusion: Based on the acceptable level of reliability and validity of the WRQoL-2 questionnaire, use the questionnaire to assess the quality of work life of nurses is recommended.

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Introduction: Extensive human and economic losses due to the fire accidents shows the necessity of scientifically dealing with major industrial fires, , investing in the development of fire protection technologies and determination of the most effective techniques to limit damages. This study is conducted to evaluate the effect of active and passive protection methods on reducing the level of fire risk, in the control room of a thermal power plant.

Material and Method: In the first phase of this study, fire risk level for buildings, goods, occupants and activities was calculated using Fire Risk Assessment Method for Engineering. In the second phase, from 36 sub-factors affecting risk level, three sub-factors of passive protection measures and two sub-factors of active protection measures were analyzed and modified, in reducing the fire risk level of occupants.

Result: The results of the present study showed that occupants’ fire risk level (20.64) is above the acceptable level. Correction of three sub-factors, including constant fire load, floor number, and changing the dimensions and area of the control room up to 40% and installing an automatic fire extinguishing system and training the occupants to use fire extinguishing equipment and emergency evacuation up to 33%, is effective in reducing the fire risk level.

Conclusion: Passive and active protection methods, despite their impacts on reducing the level of risk, cannot provide an acceptable level of fire safety independently. Therefore, combined use of these methods is essential to protect buildings and people, and prevent any interruption in the system’s activities.

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Introduction: This paper aims to explore the main effect of night shift rotation speed on the pattern of melatonin secretion and the sleepiness, among control room operators (CORs) in a petrochemical industry
Material and method: In this study, 60 CORs operators within two different patterns, including 7 nights and 3 nights shift works were selected from a petrochemical industry to investigate the influence of rotation speed on their melatonin secretion and the sleepiness pattern. Thus, melatonin was sampled from saliva, and the sleepiness and sleep quality were assessed using Karolinska Sleepiness Scale (KSS) index. Data analysis was carried out using spss18, Chi square, t-test, and GLM model.
Results: Melatonin values and their general changes during shift were noticeably different in two proposed patterns (P <0.05). The sleepiness index was significantly different only at 3:00 in both patterns, whereas the interaction of light and caffeine on both melatonin changes and sleepiness was not significant (P <0.05). Moreover, a significant difference was observed between the process of melatonin changes and sleepiness in the two studied patterns (P <0.05).
Conclusion: Adopting slower shift schedules rotations would be more appropriate, from the viewpoints of the importance of alertness and performance for human error prevention, among people working in serious worksites such as control rooms.

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Introduction: Workers in car manufacturing industry are at risk of a high prevalence of musculoskeletal disorders, especially low back pain. Therefore, in the present study aimed to design and fabricate a portable device to evaluate the low back kinematics and to compare these variables in workers with and without low back pain (LBP) in assembly lines of an automotive industry.
Material and Methods: In the present research workers postures were assessed using OWAS direct observational method. Moreover, simultaneously, prevalence and intensity of low back pain were evaluated by Dutch Musculoskeletal Questionnaire (DMQ) and Visual Analogue Scale (VAS). After fabricating motion analysis device, a field study was conducted using the designed device among 16 volunteers to investigate low back kinematic variables in two groups of workers: LBP and non-LBP.
Results: The results showed that 62.1 percent of all working postures were high risk with corrective action levels of 3 and 4. On average, 86.1 percent of workers experienced LBP in the previous 12 months. Regarding comparison of kinematic variable in the two groups of LBP and non-LBP, workers without LBP had higher degree and duration (in second) of movements (forward flexion, lateral bending, extension, and twisting), as compared to those with LBP. However, only movement range of forward flexion in non-LBP group (mean: 64.29 and SD: 8.41), was significantly higher than those with LBP (mean: 58.97 and SD: 11.34).  
Conclusion: The device can be used as an effective tool in the ergonomics studies in the field of back pain, due to its potential to record the kinematics of the trunk, as well as its lightweight and non-interference with the task. Device’s validity was acceptable based on the comparison of the results of this device with those obtained from inclinometer.

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Introduction: Perpetration of samples is one of the most important stages needed for trace residue analysis of biological specimens when human exposure assessment is required. The samples preparation process makes the analyte get more purified and enriched as well as more compatible to the analysis instrument systems. The present study has concentrated on a systematic review of different articles published regarding the sample preparation methodologies of human biological samples.
Material and Methods: In this systematic review, all articles related to the development of sample preparation for trace residue analysis of heavy metals in occupational biological samples published in English during 2009-2019, were considered. To meet the desired objective of the current study and facilitate the  related articles on physiochemical sample preparation methods accessibility combined keywords of Mesh and non-Mesh, without any limitation in the type of studies, the Pubmed, Web of Science, and Scopus were considered to be searched. Noteworthy, in this study, only the articles related to the workers’ biological samples were reviewed.
Results: Based on the obtained results, after reviewing of the keywords trough websites, 2964 articles were identified. Then, the redundant papers were removed and59 articles were remained, based on their titles and abstracts,. After detailed review of selected articles, regarding the study criteria, 8 articles were selected for the final systematic review.  Five articles out of 8, (62.5%) were allocated to the development of sample preparation for mercury in biological samples. It is worth mentioning that the majority of biological samples were regarded to the urine samples (75%) in the current study. Based on the obtained results, Solid Phase Extraction (SPE), applied in 37.5% of studies, was a popular method used in sample preparation.
Conclusion: The development of sample preparation approaches indicates a great promise for specified methods with low costs and less extraction time when separating different heavy metals from complex matrices. These sample preparation and preconcentration techniques ease the analyses processes and provide the quantitative recoveries, higher sensitivity, and lower detection limits.

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Introduction: Musculoskeletal disorders (MSDs) are prevalent in work settings and are associated with high rate of prevalence and costs. Musculoskeletal conditions have multifaceted nature, and occupational factors play an important role in their development. The aim of this study was to identify the risk factors of work-related musculoskeletal disorders in the working population in Iran during 2000 to 2015.
Material and Methods: Using the appropriate search terms, articles published in the journals, student thesis, and those presented at the conferences were searched through authentic English databases (Google Scholar, Scopus, PubMed) and Farsi ones (Magiran, SID, IranMedex, Irandoc). Following removal of duplicate citations and irrelevant studies, the full texts of the remaining publications were prepared and assessed for more detail.
Results: Perceived discomfort in low back region obtained the highest score in workers of industrial, administrative, service, and agricultural settings. However, in the handicraft and educational groups, the highest percentage of discomfort was belonged to neck (66.7%). Findings showed that the most commonly used techniques for evaluation of musculoskeletal disorders and risk factors were, respectively, Nordic questionnaire (NMQ) (76%) and REBA (13.9%). Moreover, all identified risk factors were classified into eleven groups including: biomechanical, work environment design, tools, equipment, temporal aspects of job design, job content, organizational aspects, economic and financial issues, social aspects, individual characteristics, and training.
Conclusion: Overall, a wide range of risk factors reported in the previous studies were categorized in the present review. The results are suggested to be considered by managers and decision makers as a framework to take measures for controlling musculoskeletal disorders to accomplish the goal of ergonomics, which is productivity and well-being.

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Introduction: Recent evidence indicates that lighting can affect physiological and neurobehavioral human functions, referred to as non-image forming (NIF) effects of lighteffects. This study aimed to determine the effects of illumination levels and correlated color temperature (CCT) on alertness and performance under NIF conditions.
Material and Methods: In this study, 22 participants were exposed to light at various levels of illumination, including very low illuminance (<5 lux, control) and light conditions with correlated color temperatures (CCT) of 4000 K, 8000 K, and 12000 K at 300 and 500 lux. The data collection process included recording the power of brainwaves (alpha, alpha-theta, beta, and theta), sleepiness and mood scales, and cognitive performance tests for sustained attention, psychomotor vigilance task (PVT), working memory, and inhibitory capacity.
Results: The results indicated that 500 lux light conditions at correlated color temperatures of 8000 and 12000K significantly reduced normalized alpha, alpha-theta power, subjective sleepiness, and performance compared to the dim light condition. Under illumination levels of 300 and 500 lux, there were no significant differences in the measured values of the variables.
Conclusion: Lighting interventions can be used as a supplement to other strategies for increasing alertness and performance in the workplace.

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Introduction: One of the most important complications of exposure to noises is changes in the gene expression patterns. Irreversible damage to the inner ear, such as noise-induced hearing loss (NIHL), is caused by tissue damage and changes in the gene expressions in the auditory system. Changes in the GJB2 gene expression pattern lead to autosomal deafness at different loci. The present study aims to evaluate the GJB2 gene expression in cochlear tissue exposed to white noise.
Material and Methods: In this study, ten male Westar rats were divided into two experimental (W1, W2) groups of six rats and a control (normal) group of four rats. Two experimental groups were exposed to constant white noise in the frequency range of 100-20000 Hz and the sound pressure level of 118-120 dB. In order to study the histology and gene expression, after a cochlea biopsy, the histological tests, RNA extraction, cDNA synthesis, and qRT-PCR analysis were performed.
Results: The results showed that the transcript level of GJB2 was significantly decreased in both experimental groups W1 and W2 by 0.02 and 0.12-fold, respectively (p <0.05). Also, the results of the histological study showed that cochlear tissue was more seriously damaged in the W1 group than W2.
Conclusion: It can be concluded that a significant reduction in the GJB2 gene expression and irrevocable damage to auditory nerve ganglion and Reissner membrane (vestibular membrane) caused changes in the gene expression patterns in cochlear tissue and developed the risk of non-syndromic sensorineural hearing.

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Introduction: Sleep deprivation is one of the factors affecting the physiological performance of athletes and laboratory evidence has suggested a link between sleep deprivation and decreased physical performance of athletes. The aim of this study was to determine the effect of sleep deprivation on objective and subjective physiological responses of student-athletes.
Material and Methods: The research is experimental. Twenty male volunteer sports science students selected and examined in two conditions with simple random selection in counter balanced intra-group pattern. Participants examined at two controlled situation; 1) after twelve hours fasting and eight hours enough sleep, and 2) after twelve hours fasting and thirty hours quiet sleeplessness. Measurements of physiological variables including: blood pressure, heart rate, blood lactate, mental scale of pressure perception, VO2max and body temperature were examined with specialized tools. Variations in independent variable related to intervention were analyzed using t test in the significance level of P<0/05 and SPSS software.
Results: Physiological responses of blood lactate (p = 0.002), heart rate (p = 0.01), ratings of perceived exertion (p = 0.002), time to exhaustion (p = 0.001), blood pressure (p = 0.01) =) and body temperature (p = 0.002), after deprivation of sleep to a debilitating activity in the post-test compared to the pre-test increased and the maximum oxygen consumption (p = 0.001) decreased significantly, which was also statistically significant. The findings of the present study showed that sleep deprivation can cause a significant change in the objective and subjective physiological responses of sports students.
Conclusion: According to the results of the present study, it was found that 30 hours of sleep deprivation caused significant changes in the objective and subjective physiological responses of athlete students. In a general conclusion, the findings of the present study showed that sleep deprivation should be mentioned as one of the potential limiting factors of physiological function.

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Introduction: Usability has been defined as the extent to which specific users can efficiently use a product to achieve specific goals. Along with the increased number of the elderly population, there is a need for user-centered products for this group of people. Smartphones are widely used products in modern society. USE (Usefulness, Satisfaction, and Ease of use) questionnaire is an easy-to-use, quick, and accurate instrument to assess product/service usability. Thus, this study was done to determine the validity and reliability of the Farsi version of the USE questionnaire to evaluate the usability of smartphones for elderly users.
Material and Methods: The USE questionnaire was developed by Lund (2001) to assess usability, considering four separate dimensions: usefulness, satisfaction, ease of use, and ease of learning. This is a 30-item questionnaire that evaluates usability on a 7-point Likert scale. In order to assess the face and content validity of the questionnaire, a panel of nine experts was asked to rate the relevancy, clarity, simplicity, and necessity of each question using the Likert scale. Subsequently, the Content Validity Ratio (CVR) and Content Validity Index (CVI) were computed. In order to confirm the reliability of the questionnaire, two methods of internal reliability and test-retest reliability were used. In this sense, Cronbach’s alpha was calculated as the measure of internal reliability. Cronbach’s alpha equal to and above 0.7 was considered the minimum acceptable value. To measure the test-retest, 50 old adults (aged 60 years old and above) were asked to answer the questionnaire twice at a two-week interval. Then, the Pearson correlation coefficient was calculated between the two sets of scores. Also, the receiver operating characteristic (ROC) curve was utilized for specifying its sensitivity, specificity, and cut -off point
Results: Based on the comments of the expert panel, CVI scores of all questionnaire items were above 0.78, whereas four items rated less than 0.78 in terms of CVR scores; and, consequently, were removed from the questionnaire. Moreover, according to the reliability assessment results, both internal correlation and test-retest scores obtained acceptable values. Specifically, Cronbach’s alpha coefficient for usefulness, satisfaction, ease of use, and ease of learning were 0.771, 0.862, 0.756, and 0.798, respectively. In the ROC curve, the cut-off point was reported as 4.88 with the sensitivity and specificity of 97.8% and 75%, respectively, and area under the ROC curve at this cut-off point was obtained 81%.
Conclusion: Comparing a product’s characteristics with standards is a prerequisite to determining the level of usability of that product. The Farsi version of the USE questionnaire is a reliable tool for measuring usability with satisfactory validity and reliability. This questionnaire can be used in future studies in smartphone usability.

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Introduction: In recent years, the manufacture of air purification media, especially nanofiber filters using polymeric materials and the electrospinning method, has received much attention in air pollution control. The production of high-performance media and low-pressure drops is an important issue in air filtration. This study aimed to investigate the feasibility of fabricating electrospinning polyethylene terephthalate (PET) media to abduct submicron and micron particles from the air stream.
Material and Methods: To determine the optimal device conditions in the manufacture of PET media, different weight percentages of a PET polymer solution in a mixture of trifluoroacetic acid and dichloromethane solvents (70:30) were first prepared in a pilot study, and various parameters of the electrospinning device were examined and analyzed along with performing the electrospinning process. The surface and morphological characteristics of the media were evaluated using SEM. The pressure drop and efficiency of particle trapping were assessed using a mask and media pressure by a pressure drop test device.
Results: The optimal electrospinning conditions of the PET polymer solution were obtained at a concentration of 20%. The average diameter of nanofibers PET was 163 ± 600 nm with a pressure drop of 26.33 ± 5.5 pa, and average efficiencies of 97.42 ± 1.67% and 99.85 ± 0.21 were obtained for submicron and micron particles, respectively, with a quality factor (QF) value of 0.1740.
Conclusion: The produced media can abduct and remove particles from the air stream for submicron and micron particles in ranges of 96-99% and 99-100%, respectively, with an average pressure drop of 26.33±5.5 pa.

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Introduction: Given the high prevalence of low back pain in manual handling activities, its known relationship with spinal loads, and the role of muscular fatigue and the body’s adaptive mechanisms to counteract fatigue, this study investigated the effect of repetitive lifting tasks on trunk muscular fatigue and the kinematics of the spine and load-in-hand.
Material and Methods: Eighteen male volunteers lifted a box from the floor to their waist height at a pace of ten lifts per minute until they could no longer continue the task and reported the highest level of exhaustion. Kinematic data and muscle electromyographic activity were simultaneously recorded using a motion capture system and an electromyography device. In this study, average trunk flexion angle and trunk angular velocity were calculated as trunk kinematic variables, while average box vertical travel distance, average box horizontal displacement from L5-S1, and average box vertical displacement velocity were considered as box kinematic variables. The median frequency of electromyographic signals from selected muscles was quantified as a muscle fatigue indicator. Since subjects performed different lifting cycles, the total number of cycles was divided into five distinct blocks for data analysis.
Results: The results showed significant effects of lifting trial blocks on trunk angle (p=0.004) and vertical box displacement (p<0.001). Median frequency was significantly affected by lifting blocks for right (p=0.016) and left erector spinae (p=0.014), right (p=0.021) and left multifidus (p<0.001), right latissimus dorsi (p=0.001), and left rectus abdominis (p=0.039).
Conclusion: Overall, the results highlight variations in most kinematic parameters and a reduction in the frequency content of EMG signal spectra. These changes serve as indices of the central nervous system’s control over lifting behavior under dynamic conditions. A better understanding of these central nervous system adaptations could have practical applications in interventions such as workstation design, exoskeleton development, and worker training to manage musculoskeletal disorders.

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Introduction: In many occupations, users must sit for prolonged periods during their job activities. Prolonged sitting is associated with fatigue, leading to postural changes that can increase spinal loads. Despite the importance of this topic in terms of the extent of prolonged sitting and its subsequent adverse consequences, little attention has been given to this occupational activity. Hence, this study investigates changes in neck, trunk, and muscle activities and fatigue levels in prolonged sitting computer tasks.
Material and Methods: Twenty healthy subjects (gender-balanced) from the student community with at least five years of experience in computer work aged between 20-30 years were asked to randomly perform three types of computer tasks for 90 minutes (each task for 30 minutes). Electromyographic (EMG) activities of right and left cervical (ESCR and ESCL), thoracic (ESTR and ESTL), and lumbar (ESLR and ESLL) erector spine and upper trapezius (UTR and UTL) muscles were continuously recorded. Root mean square (RMS) and median frequency were extracted as EMG metrics. Subjects also rated their perceived discomfort using a Visual Analogue Scale (VAS). The effect of time, gender, and their interaction on muscle EMG activities, fatigue, and discomfort were explored.
Results: Time had a statistically significant effect on UTR, ESCR, and ESTR muscle activities. UTL and ESCR muscle activities significantly differed between male and female subjects. Further, the findings confirmed the interactive effect of time and gender on ESTR muscle activity. UTR, ESCR, ESCL, ESTL, and ESLL muscles’ fatigue index changed statistically over time.
Conclusion: The findings confirmed neck and trunk muscles’ fatigue by increasing muscular activity and reducing frequency contents over time, per the subjective rating of discomfort.

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Introduction: Prolonged sitting postures are among the risk factors for musculoskeletal disorders in occupational settings, leading to increased musculoskeletal discomfort in various body regions. This discomfort can negatively impact individuals’ health and impose high costs on society in terms of work absences, early disabilities, and reduced productivity. The purpose of this study is to investigate the effect of stretching exercises on the level of discomfort, muscle activity, and muscle fatigue in the neck and trunk region during prolonged sitting tasks.
Material and Methods: This experimental study was conducted among 20 healthy male and female participants under two test conditions: control and intervention. In the control condition, participants performed cognitive tasks (watching videos, typing, text editing, and nback cognitive test) without any intervention. In the intervention condition, participants performed stretching exercises before each task. The Visual Analogue Scale was used to assess perceived discomfort. Also, muscle fatigue was evaluated using an electromyography (EMG) device and RMS and MPF measures.
Results: Discomfort in hands and arms (p-value=0.04) and lower back (p-value=0.03) during video-watching was higher in the control condition than in the intervention. Regarding muscle activity, the activity of the right cervical erector spinae during the video-watching task was lower in the control condition than in the intervention. In the n-back cognitive test and text editing, the right lumbar erector spinae muscle activity was significantly higher in the control condition than in the stretching exercises intervention. Regarding the left cervical erector spinae, a significant difference was observed between fatigue in control and intervention conditions during the video-watching task. Also, right thoracic erector spinae fatigue in text editing was higher in the control condition than in the exercise intervention; however, for the n-back test, the level of fatigue was lower in the control condition compared to the intervention.
Conclusion: The perceived discomfort in seated computer tasks is generally lower in the exercise intervention compared to the control condition. The stretching exercises used in this study improved muscle activity and reduced fatigue in some of the trunk muscles, although the effects of the exercises depend on the type of task. Overall, muscle fatigue in two cognitive tasks, text editing and n-back, was more affected by stretching exercises than other tasks.

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Introduction: This study aimed to analyze the effects of endurance training (Aerobic) on the levels of inflammatory markers (IL-6/TNF-α) and some metabolic parameters in male rats with non-alcoholic fatty liver disease to investigate the feasibility of using exercise training to reduce inflammation.
Material and Methods: A total of 44 Wistar rats were randomly assigned into two groups: (I) standard diet group of 22 rats and (II) high-fat diet group with 22 rats supplemented with free access to fructose water. After 17 weeks, two rats from each group were sacrificed, and liver tissue was collected for hematoxylin-eosin staining. Subsequently, the remaining 20 rats in the (I) group were divided into a training group (T) and a control group (C). The 20 rats in the (II) group supplemented with fructose water were divided into a fatty liver group (FL) and a fatty liver + training group (FL+T), each comprising ten rats. In the next phase, the T-groups underwent an eight-week endurance training intervention. Then, IL-6, TNF-α, glucose, insulin, insulin resistance and sensitivity levels were measured.
Results: The results of the present study showed that as a result of a high-fat diet with liquid fructose in HFD+HF group rats, non-alcoholic fatty liver disease (NAFLD) with complications such as a significant increase in the levels of IL-6 and TNF-α, Hepatic dysfunction, and metabolic parameters were disturbed (p<0.001). However, endurance training improved most of these complications by reversing the disease process (p<0.001).
Conclusion: According to the results of the present study, it can be concluded that the improvement of inflammatory markers, liver dysfunction, and metabolic parameters through endurance training is one of the key mechanisms of exercise in the treatment of NAFLD, the consequences of which may show the importance of endurance training in treatment of NAFLD highlights.

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Introduction: Operating room personnel are involved with occupational physical activities such as repetitive bending, holding surgical tools and standing for long hours that can lead to musculoskeletal disorders (MSDs). Low back pain (LBP) is the most prevalent and costly problem among these disorders. The aim of this study was to determine the relationship between occupational physical activity, LBP and disability among operating room personnel.
Material and Methods: A total of 60 operating room personnel voluntarily participated in the study, all of which had at least two years of working experience. At the end of a working week, the degree of disability and pain were assessed by Graded Chronic Pain (GCP) questionnaire. The International Physical Activity Questionnaire (IPAQ) was used to evaluate the level of physical activity. Simple linear regression was conducted to investigate the relationship between physical activity, LBP and disability. 
Results: The survey using the GCP questionnaire revealed that 58.3% of participants reported experiencing occupational back pain, while 41.7% reported no back pain.  Among those with back pain, the average pain intensity was rated 43.11 (18.22) on the scale.  Pain remained stable for an average of 2.3 days (standard deviation = 0.95).  The average level of disability associated with back pain was 32.09 (27.44). Statistical analysis using simple linear regression showed a significant relationship between back pain and several factors: vigorous physical activity (p-value = 0.02), prolonged sitting time (p-value = 0.01), and chronic pain (p-value < 0.001).
Conclusion: Occupational physical activity characterized by low intensity, but high repetition and standing for a long time in fixed postures were the most significant contributors to lumbar back pain among operating room personnel. Chronic pain in this population was reported as grade 2, indicating severe pain with minimal disability; if left unaddressed, this could lead to movement restrictions.