Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals.

BACKGROUND: Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. METHODS: The current study was conducted on 20 congenital blind and 10 sighted people (15-38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. RESULTS: In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. CONCLUSION: Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Assessing the effectiveness of an ergonomics intervention program with a participatory approach: ergonomics settlement in an Iranian steel industry.

PURPOSE: Work-related musculoskeletal disorders (WMSDs) are common occupational problems affecting the health and productivity of workers worldwide. Ergonomic intervention programs (EIPs) can play an effective role in preventing these disorders in the workplace. Assessing the effectiveness of an EIP is a challenge faced by both industries and researchers. This study was aimed at assessing the effectiveness of an EIP on human resources productivity (HRP), musculoskeletal disorders (MSDs), general health and occupational fatigue in a steel industry. METHODS: This study was conducted in a steel industry in Isfahan, Iran, between 2018 and 2021. To assess the effectiveness of the EIP with a participatory approach, training and redesign of workstations, the criteria of HRP, MSDs, general health and occupational fatigue were investigated before and after the intervention, using HRP Questionnaire, Nordic musculoskeletal questionnaire (NMQ), 28-item General Health Questionnaire (28-GHQ), Swedish Occupational Fatigue Inventory (SOFI-20) and Occupational Fatigue/Exhaustion Recovery (OFER-15) Questionnaire, as data collection tools, respectively. RESULTS: The implementation of EIP in the studied industry significantly led to an increase in HRP (p < 0.05). The prevalence of MSDs decreased significantly in most regions of the body after the interventions (p < 0.001). In addition, the program significantly improved general health (p < 0.001) and reduced occupational fatigue among employees (p < 0.001). CONCLUSIONS: The implementation of EIP was significantly effective in working conditions improvement. Therefore, implementing EIP with participatory approach, workforce training, as well as redesigning of workstations are recommended in industries.

Effects of an ergonomic intervention program based on the PRECEDE-PROCEED model for reducing work-related health problems and exposure risks among emergency medical dispatchers.

OBJECTIVE: To evaluate the effectiveness of an ergonomic intervention program based on the PRECEDE-PROCEED model in terms of improving exposure risks and work-related health problems in emergency medical dispatchers. METHODS: This quasi-experimental study used an interrupted time series design. Participants were 55 employees working in an Emergency Medical Communications Center in Iran. The intervention program was based on the PRECEDE-PROCEED model and included five face-to-face training sessions and installing auxiliary equipment according to best ergonomic principles. Direct observations of the emergency medical dispatchers' working postures using the Rapid Office Strain Assessment and a survey which included a modified Nordic Questionnaire, Work Ability Score, Visual Fatigue Questionnaire, and a Behavioral Factors Questionnaire were used at three time points: baseline, 1 month post-intervention, and 3 months post-intervention. RESULTS: The modified Nordic Questionnaire showed significant reductions in pain intensity scores for neck, lower back, knee and ankle after the ergonomic intervention program. In addition, there were considerable post-training improvements in behavioral factors (knowledge and enabling factors) and working postures. No significant changes were observed in Work Ability Scores, or visual symptoms. CONCLUSIONS: An ergonomic intervention program based on a systematic framework such as the PRECEDE-PROCEED model and on-site interventions can be effective in improving and enhancing the working conditions of emergency medical dispatchers. Therefore, it is suggested that ergonomic interventions be implemented based on standard and valid behavioral change models such as PRECEDE-PROCEED model in other work environments in which musculoskeletal pain and digital eye strain are common.

Physical and psychological workloads and their association with occupational fatigue among hospital service personnel.

BACKGROUND: Physical and psychological workloads are a vital issue in the workplace. This study aimed to investigate the association between physical and psychological workloads and occupational fatigue among Iranian hospital service personnel. In Iran, hospital service personnel refers to a group of healthcare workers who undertake a range of duties, such as moving and carrying the hospital waste, transporting patients by wheelchair or gurney to the operating room, x-ray department, other wards, or other locations around the facility, performing cleaning tasks such as changing linens, mopping floors, and sterilizing equipment, and following infection control procedures to reduce the risk of spreading germs within the hospital setting. METHODS: This cross-sectional study was conducted on 198 Iranian hospital service personnel. The response rate was 86%. The data were gathered using 1) The Persian version of the Job Content Questionnaire (P-JCQ) for assessing physical and psychosocial workloads and 2) The Persian version of the Swedish Occupational Fatigue Inventory (P-SOFI-20) for assessing fatigue dimensions. RESULTS: According to the P-JCQ, the physical and psychological workload intensities were high in 72.7% and 47% of the participants, respectively. Based on the P-SOFI, the participants' mean scores of "physical fatigue" (21.73 ± 6.2), "psychological fatigue" (13.61 ± 5.76), and "fatigue due to shift work" (18.17 ± 5.6) were moderate, while the mean score of "general fatigue" was high (27.3 ± 6.98). The findings revealed that various types of fatigue are associated with age, gender, marital status, daily working hours, and psychological workload. CONCLUSIONS: Psychological workload was a determinant of occupational fatigue among Iranian hospital service personnel. Hence, an interventional program, including job enrichment, job rotation, and work-rest cycle, is recommended.

Employing a three-stage procedure to develop a sizing system for medical gloves.

There is a need for gloves that are designed based on the dimensions of the hand of each society because the proper size is a key factor that affects performance. This study aimed to design and develop a glove-sizing system for Iranian healthcare workers using anthropometric data. This study was conducted on a sample including 540 healthcare workers across Iran classified by ethnicity and gender. Thirty-three dimensions were measured as the anthropometric data. Principal Component Analysis (PCA) and clustering analysis were used to create classifications for glove sizes. The most effective dimensions in defining the hand sizes of Iranian healthcare workers were middle finger length and the handbreadth. The designed six-size system covered 94% of the sample. This system can be used to design suitable gloves for Iranians. The sizes presented can be used to compare size differences in different communities. Practitioner summary: In this study, an attempt was made to design a sizing system with maximum coverage for medical gloves using statistical analysis methods and hand anthropometric dimensions of Iranian healthcare workers. The method of this study can be used in other communities as well for improving sizing systems.Abbreviations: PCA: Principal Component Analysis; GSS: Glove Sizing Systems; TEM: Technical error of measurement; R: Reliability coefficient; KMO: The Kaiser-Meyer-Olkin; PC1: The first principal component; PC2: The second principal component; FCMC: Fuzzy c-means clustering; XS: Very small; S: Small; SM: Medium small; LM: Medium large; L: Large; Xl: Very large.

Developing a Decision Aid Tool for selecting pen-paper observational ergonomics techniques: a quasi-experimental study.

BACKGROUND: A significant error that may occur during ergonomic risk assessment and invalidate assessment reliability corresponds to technique selection. This study aimed to develop a new tool called the Decision Aid Tool (DAT) to reduce pen-paper observational technique selection errors. METHODS: This quasi-experiment before-after study was performed in three phases. In the first phase, the participants' skills in technique selection were examined by showing them 20 videos of different single-task jobs. In the second phase, the DAT was designed using pen-paper observational techniques. Finally, in the third phase, 115 occupational health specialists included in the study through purposive sampling of experts evaluated the tool's efficacy. RESULTS: The results of the first phase showed that 62% of participants made an error in selecting the proper technique. The mean and standard deviation scores from the first and third phases were 11.4 ± 6.59 and 39.01 ±1.89, respectively. The mean scores increased significantly after using DAT, and 97.5% of participants could correctly select task techniques. CONCLUSIONS: The efficacy of DAT was confirmed in a quasi-experimental before-and-after study. Using DAT increases the participants' ability to choose the correct technique. The DAT can be functional for practitioners to select the pen-paper observational techniques correctly under the purpose of assessment, the body areas, and the characteristics of the task to be assessed.

Investigation of psychosocial factors on upper limb musculoskeletal disorders and the prevalence of its musculoskeletal disorders among nurses: a systematic review and meta-analysis.

OBJECTIVE: Musculoskeletal disorders are one of the most important occupational problems especially among nurses. The aim of this study was to investigate the prevalence of musculoskeletal disorders in upper limbs and its associated psychosocial factors in the workplace. METHODS: A systematic review was conducted by searching the Medline/PubMed, EMBASE, Scopus, ISI/web of knowledge and Google Scholar databases. The authors classified studies into categories of psychological work stressors and musculoskeletal problems. The statistical analysis was performed using Stata software. RESULTS: We found 1742 articles in our initial search. After reviewing the titles, abstracts and full texts, 66 articles were finally analyzed. Psychosocial factors affecting the prevalence of upper limb musculoskeletal disorders among nurses were identified which included boring work, inadequate staffing, job demands, insufficient support, time pressure, decision latitude, job dissatisfaction, and job stress. There was a significant relationship between these factors and prevalence of musculoskeletal disorders in the wrists, shoulders, neck and shoulders, and wrists and hands. CONCLUSION: Collectively, the results of this study provide strong evidence of some psychosocial factors affecting the prevalence of upper limb musculoskeletal disorders among nurses. Thus, organizational interventions to minimize these stressors may be promising in reducing one risk factor for the development of nurses' musculoskeletal disorders. These interventions should not only consider the factors of physical ergonomics but also seek to improve the organizational aspects of the workplace.

Development and validation of a Nurse Station Ergonomics Assessment (NSEA) tool.

BACKGROUND: Nurse stations are one of the primary units for supporting effective functioning of any hospital. They are important working environments that demand adherence to known ergonomic principles for the well-being of both staff and patients. The aim of this study was to develop a psychometrically tested tool for the assessment of the ergonomic conditions of nurse workstations in hospitals. METHODS: Ten hospitals, with a total of 133 nurse stations participated in this mixed-methods research. The domains and items of the tool were developed based on a literature review, an experts' panel, and interviews with nurses. RESULTS: The final nurse station ergonomic assessment (NSEA) tool has good psychometric properties. Validity was assessed by face validity and content validity. Reliability was evaluated using inter-rater agreement and test-retest reliability analyses with a four-week interval between assessments. The NSEA is comprised of 64 items across eight domains: layout and location (7 items), workspace (11 items), security-safety (5 items), environmental conditions (8 items), counter (8 items), chair (13 items), desk (9 items), and monitor (3 items). CONCLUSIONS: The NSEA adds to the literature a tool for managers to ensure they comply with legal requirements and support best practice for those working on hospital wards. The NSEA can be used to identify challenges for healthcare professionals who use nurse stations and support the execution of targeted interventions to improve human-environment interactions.

Evaluation of a passive low-back support exoskeleton (Ergo-Vest) for manual waste collection.

The purpose of study was to determine the biomechanical, physiological, and subjective effect of a Passive Exoskeleton device (called Ergo-Vest) among 20 waste collectors in the working environment. Compression force and moment on L4/L5 related to 400 critical postures of the participants were estimated using the 3DSSPP software. The heart rate and energy expenditure are measured as the physiological strain using the Polar RS400 Heart Rate Monitor. Borg scale perceived exertion, system usability scale, and ergonomic design indicators of the device were collected as the subjective parameters. Compression force and moment on L4/L5 disc were decreased when the Ergo-Vest was utilised. There was no significant difference in energy expenditure and heart rate with and without the device. The workers' perceived physical exertion was decreased while using the Ergo-Vest. From the perspective of end users, the usability and ergonomic design features of the Ergo-Vest was acceptable. Practitioner summary: The prevalence of musculoskeletal disorders is high among the Iranian waste collectors. To mitigate this occupational problem, the effect of a passive exoskeleton for lower-back support (Ergo-Vest) was investigated on the workers' spine loading, physiological parameters, and perceived physical exertion. The result shows spine force reduction and lower subjective responses.

The Medical Gloves Assessment Tool (MGAT): Developing and validating a quantitative tool for assessing the safety and ergonomic features related to medical gloves.

BACKGROUND: Medical gloves play a very important role in protecting health care workers and patients. It is very important to pay attention to the safety and ergonomic properties of medical gloves in their protective function. AIM: To develop a quantitative tool for evaluating the safety and ergonomic properties of the medical gloves. METHODS: Five hospitals with a total of 185 health care workers participated in the research. The domains and items of the tool were developed based on an expert's panel, interviews with health care workers and a literature review. Face, content and construct validity was used for validation. Reliability was also evaluated using internal consistency. RESULTS: The final tool included 26 items in six domains, including tactile sensation, dexterity, grip strength, fitting, reliability and hand hygiene. The Cronbach's alpha was 0.82 for the total scale. CONCLUSION: The final tool had good validity and reliability. The findings of this study led to the development of a comprehensive standard tool that can be used to assess the ergonomic and safety status of medical gloves. IMPLICATIONS FOR NURSING MANAGEMENT: With this tool, problems related to medical gloves can be identified among nurses, and the necessary interventions can be predicted.

Prevalence of musculoskeletal disorders, ergonomics risk assessment and implementation of participatory ergonomics program for pistachio farm workers.

BACKGROUND AND OBJECTIVES: Pistachio farmers are exposed to a variety of risk factors for musculoskeletal disorders (MSDs). However, no study has been conducted to investigate MSDs in pistachio workers. Therefore, in the present study, besides investigating the prevalence of MSDs and their ergonomic risk factors, the participatory ergonomics (PE) method is used to provide an intervention program to reduce MSDs in this population in harvesting and processing pistachio. METHODS: The present study was conducted in two phases. In the first phase 138 workers participated. The prevalence of MSDs was assessed with Nordic Musculoskeletal Questionnaire and the ergonomic risk factors was identified with ManTRA method. In the second phase PE was used to perform ergonomic interventions for reducing MSDs and the effect of the intervention was investigated. Sixty-four workers participated in the second phase (32 in the case group and 32 in the control group). RESULTS: The highest prevalence of MSDs was in shoulders (63.7%), followed by the lower back (63%) and wrists/hands (52.1%). The comparison showed that after implementing the PE intervention program, the prevalence of MSDs in the intervention group was not significantly different from that in the control group. However, in the reassessment by the ManTRA method for five tasks that were identified as high risk in the first phase, a decrease in ManTRA final score was observed for all the five tasks. CONCLUSIONS: MSDs were prevalent in all body regions of workers. After implementing PE interventions exposure to ergonomic risk factors decreased.

Relationship between personality type and musculoskeletal disorders among office staff.

BACKGROUND: Musculoskeletal disorders (MSDs) have been recognized as common health-related problems in the workplace. Accordingly, poorly-designed workstations and assigned tasks can lead to exposure to risk factors inducing MSDs among office staff. Accompanied by physical risk factors, psychological ones in working environments can also contribute to MSDs occurrence. Thus, the purpose of this study was to examine the relationship between personality types as a psychological factor and MSDs occurrence among office staff. METHODS: This cross-sectional study was carried out on office staff working at Shiraz University of Medical Sciences (SUMS) in 2016. The participants included 339 employees recruited using multi-stage simple random sampling method. The required data were likewise collected via a demographic characteristics information checklist, the Personality Pattern Questionnaire (PPQ), as well as the standardized Nordic Musculoskeletal Questionnaire (NMQ). RESULTS: The findings revealed that the participants' mean±standard deviation (SD) age were 36.4±7.8 years. As well, the most prevalent MSDs complaints were reported in lower back, knee, and neck regions with relative frequencies of 35%, 30%, and 25% respectively. Moreover, the results demonstrated that 0.6% of the participants were determined as individuals having a strong tendency for type A personality, 26.8% of them showed tendency for type A personality, 63.1% of these employees were categorized into those having a tendency for type B personality, and 9.4% of them were identified as participants who showed a strong tendency for type B personality. Additionally, statistically significant relationships were observed between personality types and MSDs occurrence (p=0.023). Furthermore, musculoskeletal symptoms were reported more prevalent among individuals having tendency for type A personality. CONCLUSION: Personality types and MSDs occurrence seemed to be associated. It was thus suggested to take account of psychological factors (e.g., personality types) in macro policy-making, employee selection, and professional staff training programs.

The relationship between work-related psychosocial factors and burnout among Iranian nurses: Job Demand-Control-Support model.

BACKGROUND: Nursing work environment consists of a number of work-related psychosocial risk factors such as excessive workloads, lack of social support, emotional demands, job insecurity and confronting with challenging situations all of which may induce burnout. The aim of the current study was to investigate the relationship between work-related psychosocial factors and burnout among Iranian nurses. METHODS: A cross-sectional study was carried out among 522 nurses. The data related to work-related psychosocial factors and burnout was gathered using Job Content Questionnaire (JCQ) and Maslach Burnout Inventory (MBI), respectively. Pearson's correlation coefficients were used to examine the relationship between work-related psychosocial factors and burnout. RESULTS: Mean scores of the dimensions of burnout for emotional exhaustion, depersonalization, and reduced personal accomplishment were 13.6 (SD=8.6), 18.42 (SD=7.1), and 28.45 (SD= 9.15), respectively. Psychological and physical job demands were positively correlated with different dimensions of burnout while social support and job control showed negative correlation with them. CONCLUSION: Appropriate interventions on reducing job demands both psychologically and physically and increasing social support and job control are suggested in prevention of burnout among the studied nurses.

Assessment of mental workload and its association with work ability in control room operators.

BACKGROUND: Modern technology has reduced physical workload and imposed high mental workload on the control room operators in industrial settings. The present study was conducted among control room operators to assess their mental workload, investigate their workability, examine the relationship between mental workload and workability, and determine the factors associated with workability. METHODS: This cross-sectional study was carried out among 213 control room operators in six Iranian process industries. Task Load Index (NASA-TLX) was used to assess the mental workload, and Work Ability Index (WAI) was used to determine workability. The relationships between demographic characteristics and dimensions of mental workload and workability were examined by univariate tests. Logistic regression analysis was also used to determine the factors associated with the operators' workability. RESULTS: The results showed a high mental workload in the study population (82.38±8.8). Yet, the operators showed a good and excellent level of workability (56.4%). Pearson's correlation coefficient revealed a significant inverse linear relationship between the mean score of mental workload and workability (r=-0.581). Besides, regression modeling demonstrated that mental demand (OR=0.90), temporal demand (OR=0.90), effort (OR=0.91), frustration (OR=0.92), from NASA-TLX subscales were significantly associated with workability. Moreover, mental and temporal demands were important factors associated with reduced workability. CONCLUSION: Monitoring tasks imposes high mental workload on the control room operators, which may result in adverse effects on their workability as well as on the safety of the system.

Relationship between circadian rhythm amplitude and stability with sleep quality and sleepiness among shift nurses and health care workers.

INTRODUCTION: Sleep is affected by the circadian cycle and its features. Amplitude and stability of circadian rhythm are important parameters of the circadian cycle. This study aims to examine the relationship between amplitude and stability of circadian rhythm with sleep quality and sleepiness. METHOD: In this cross-sectional research, 315 shift nurses and health care workers from educational hospitals of Kerman University of Medical Sciences (KUMS), Iran, were selected using a random sampling method. The Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and Circadian Type Inventory (CTI) were used to collect the required data. RESULTS: In this study, 83.2% suffered from poor sleep and one-half had moderate and excessive sleepiness. The results showed that flexibility in circadian rhythm stability, job stress and sleepiness are among the factors affecting quality sleep in shift workers. DISCUSSION: Those whose circadian rhythm amplitude was languid suffered more from sleepiness and those whose circadian stability was flexible had a better sleep. Variables including circadian rhythm stability (flexible/rigid) and amplitude (languid/vigorous) can act as predictive indices in order to employ people in a shift work system so that sleepiness and a drop in quality of sleep are prevented.

Assessment of functional parameters and comfort of a new computer mouse as compared with other types of input devices.

BACKGROUND: This study was conducted to assess functional parameters and comfort of a new computer mouse (Ergomice) as compared with three other input devices. MATERIALS AND METHODS: Functional parameters (i.e., task completion time and error rate) of each device were assessed by 10 participants using standardized software based on Standard No. ISO 9241-9:2000. Comfort evaluation was also undertaken for each device using the visual analogue scale technique. Statistical analysis including the Wilcoxon signed-rank test and the Friedman test was performed using SPSS version 16. RESULTS: The functional parameters of the standard mouse were better than those of the other devices. However, no significant difference was observed between this mouse and Ergomice. Overall comfort evaluation showed that the standard mouse and Ergomice were more comfortable to work with. The comfort level of hand/wrist posture in the Ergomice was higher than that of the other three devices. CONCLUSION: The design features of Ergomice could improve its functional properties. Hand/wrist posture comfort of Ergomice was judged to be high compared with that of the other devices.

Looking beyond the screen: A systematic review of safety in control rooms.

As a complex socio-technical system, the Control Room (CR) is central to many industries, such as process, aviation, transportation, and mining. CRs' complexity impacts the safety, operational, engineering, regulatory, and financial performance of the system. In this study, a search strategy was defined and applied to three reputable databases: Scopus, Web of Science, and PubMed. The search results underwent a two-stage screening process based on inclusion and exclusion criteria. The inclusion criteria were investigating the safety in the CR, full-text availability, and writing in English. The exclusion criteria were unrelated to the safety in the CR, non-English Language, and non-original studies. A total of 59 studies were included in the analysis. The included articles were systematically reviewed from the Human Reliability Assessment (HRA) and Human Factors Engineering (HFE) perspectives. Since these records covered various subjects related to human reliability and human factor aspects, a categorization step was added to the study process. In this step, all included studies were categorized based on their subjects. A total of 7 categories were identified, including reliability (17 documents), safety performance (13 documents), decision-support systems (7 documents), fire safety (2 documents), communication/teamwork (11 documents), situation awareness (4 documents), and others (5 documents). Finally, the included studies in each category were analyzed and discussed. The results of this study help identify different aspects of safety in the control room and plan to improve their safety weaknesses, which ultimately leads to an increase in the efficiency of employees and various industries.

Validating the effectiveness of a self-report tool to predict unsafe behavior of industrial workers: a QEEG analysis.

Objectives. Unsafe behavior (UB) is defined as the likelihood of intentionally or unintentionally deviating from pre-defined plans. This study aims to investigate the validation of a self-report tool for measuring workers' cognitive-based UB using quantitative electroencephalography (QEEG). Methods. The cognitive-based unsafe behavior questionnaire (CUBQ) was completed by 632 front-line workers in a manufacturing industry to identify differences in the backgrounds of the subjects regarding UBs. Two groups were then selected as extreme groups and QEEG was conducted based on the international 10-20 electrode placement. Results. The mean values of absolute power (AP), alpha/beta ratio (ABR) and alpha/gamma ratio (AGR) from brain oscillations in different regions of the cortex were significantly different between the studied groups (p < 0.05). Additionally, these values were found to be significantly correlated with slips, lapses and mistakes, as measured by certain scales of the CUBQ (p < 0.05). Conclusions. The findings of this study indicated differences in brain oscillation activities among industrial workers with different UB backgrounds. These results confirm the effectiveness of CUBQ as a proactive tool for safety practitioners to predict industrial workers' UBs.

Assessment of Load Manual Lifting among Shelf-Stoking Workers in Chain Stores: A Cross-Sectional Study.

In Iranian stores, shelf workers, in addition to shelf-stocking, perform diverse tasks, such as working as a cashier, cleaning, barcode reading, labeling goods, and entering the price with the portable data terminal (PDT). Therefore, this study aimed to investigate the prevalence of work-related musculoskeletal symptoms (WMSs) and assess load manual lifting among shelf-stoking workers. This cross-sectional study was conducted among 101 shelf-stoking workers (60 males and 41 females) in chain stores at Shiraz city, Iran. The subjects were selected by cluster sampling from chain stores in Shiraz city, namely Refah, Canbo, Soroush, and Tirazis. Then, the required number of samples was selected and entered into the study from each cluster in proportion. The Persian version of the Nordic Musculoskeletal Questionnaire and the National Institute of Occupational Safety and Health-variable lifting index method were used to collect the required data. Data were analyzed by SPSS software version 22 using the Mann-Whitney U test, Spearman's correlation coefficient, and linear regression. Ankles/feet, lower back, and knees had the highest prevalence of WMSs among the participants. About 70.3% of workers had a VLI higher than 1. There was an association between gender and VLI. The VLI was higher in males than females. The study's findings revealed that the medians of the VLI were significantly different among participants with/without upper back symptoms during 12 months prior to the study and among participants with/without lower back symptoms during 7 days prior to the study. According to the linear regression analysis, gender and lower back symptoms during 7 days prior to the study remained in the model and were associated with the VLI. The findings revealed that the back region of the shelf-stoking workers is prone to work-related musculoskeletal disorders. In addition, based on the results, gender and lower back symptoms during the 7 days prior to the study were predicting variables for VLI. This study provides an overview of pain/discomfort and postural load in shelf-stoking workers. Since the principles of ergonomics for the placement and layout of shelves are the same in all stores, the findings of the present study can be used in other stores.

Estimation of aerobic capacity and determination of its associated factors among male workers of industrial sector of Iran.

INTRODUCTION: The aim of this study was to estimate maximal aerobic capacity (VO2 max), to determine its associated factors among workers of industrial sector of Iran and to develop a regression equation for subjects' VO2 max. METHODS: In this study, 500 healthy male workers employed in Shiraz industries participated voluntarily. The subjects' VO2 max was assessed with the ergocycle test according to the Åstrand protocol. Required data was collected with a questionnaire covering demographic details (i.e., age, job tenure, marital status, education, nature of work, shift work, smoking and weekly exercises). RESULTS: The subject's mean VO2 max was 2.69 ± 0.263 l/min. The results showed that there was an association between VO2 max and age, BMI, hours of exercise and smoking, but there was no association between VO2 max and height, weight, nature of work and working schedule. On the basis of the results, regression equations were developed to estimate VO2 max. CONCLUSION: Final regression equation developed in this study may be used to estimate VO2 max reliably without the need to use other laboratory instruments for aerobic measurement.