Physical and psychological job demands and fatigue experience among offshore workers.

Offshore operations are generally challenging and hazardous, and the workers are exposed to conditions that may lead to fatigue. A cross-sectional study evaluated physical and psychological job demands and their associations with fatigue among offshore workers. The offshore workers (n = 251) completed a questionnaire including demographic/job details, Multidimensional Fatigue Inventory (MFI‒20), and Job Content Questionnaire (JCQ). Data were analysed using linear regression modelling. Results indicated that the physical (particularly performing repetitive motions and applying pressure with hands and wrists) and psychological (e.g., intense task concentration and fast working) job demands were relatively high. The total mean (SD) fatigue score (MFI‒20) was 56.3 (13.9). Individual factors (Body Mass Index ‒ BMI), physical job demands (awkward working postures, frequent moving/lifting heavy objects and doing lots of physical efforts) and psychological job demands (task interruptions by other people and doing an excessive amount of work) were the main variables associated with different dimensions of fatigue in the multivariate models. While physical fatigue was only associated with the physical job demands, both physical and psychological job demands were significantly associated with mental fatigue in the multivariate context. The findings have possible implications for job design and implementation of intervention programmes to promote health and performance of the employees.

Effects of tool grip span, workpiece orientation, moving direction, and working height on two-handed torque strength and subjective measures.

BACKGROUND: Using both hands is regularly needed for force/torque exertions in many activities, especially when using hand tools. OBJECTIVE: To investigate the effects of tool grip span, workpiece orientation, moving direction, and working height on two-handed wrist U/R deviation torque strength, usability, comfort, and discomfort while using locking pliers. METHODS: Participants (n = 22) took part in an experimental study which evaluated the effects of tool grip span (4.5-6.5 cm), workpiece orientation (transverse/sagittal), moving direction (clockwise (CW)/counterclockwise (CCW)), and working height (shoulder/elbow/knuckle) on two-handed wrist U/R deviation torque, (dis)comfort, and usability while using locking pliers. RESULTS: The results showed no significant effect of tool grip span on wrist U/R deviation torque strength, but the locking pliers with 4.5 cm handle grip span led to more comfort and better usability. The two-handed wrist U/R deviation torque strengths were significantly higher in sagittal plane than in transverse plane, and in CW direction than in CCW direction. The highest values of two-handed wrist U/R deviation torque strength in sagittal and transverse planes were exerted in knuckle and elbow heights, respectively. CONCLUSION: The findings can be used to develop guidelines and recommendations with regard to daily and occupational activities which require the use of both hands for force exertion with manual hand tools.

T-shaped handle set-up: effects of handle diameter, between-handle distance, workpiece orientation, working height, and exertion direction on two-handed torque strength, usability, comfort, and discomfort.

The use of both hands is often required for force/torque exertions, particularly when using hand tools. This study investigated the effects of handle diameter (3-5 cm), between-handle distance (0.5-1.5 shoulder span (SS), workpiece orientation (horizontal/frontal), working height (shoulder/elbow/knuckle), and exertion direction (clockwise/counter-clockwise) on maximum two-handed torque strength, usability and comfort/discomfort while using T-shaped handles. Participants (n = 20) performed 36 experimental conditions. The handle diameter had no significant main effect on torque strength. The 3 cm diameter handle was associated with better usability and comfort compared to other options. Higher torque values were recorded with between-handle distance of 1.0 and 1.5 SS, in frontal plane, in shoulder and knuckle heights, and in counter-clockwise direction. The between-handle distance of 1.0 SS had better comfort and higher usability than other conditions. Interactions between the between-handle distance and working height, between-handle distance and workpiece orientation, and workpiece orientation and working height were also significant.Practitioner summary: Effects of handle diameter, between-handle distance, workpiece orientation, working height, and exertion direction on torque exertions, and subjective measures when using T-shaped handles were evaluated. Higher levels of strength were measured with between-handle distance of 1.0-1.5 shoulder span, and in frontal plane, in shoulder/knuckle heights, and in counter-clockwise direction.

Anthropometric data of an elderly Iranian population provides insights for system design.

BACKGROUND: Anthropometric data should be considered for each major population age category, specifically because of the dimension changes occurring during ageing. In elderly subjects, the physical activities and their capabilities become limited. Therefore anthropometric reference data for equipment and system designs is necessary. OBJECTIVES: The aim of the study was to collect data for the body dimensions of an elderly Iranian population and evaluate the related gender and age correlations. METHODS: Nineteen body dimensions were manually measured on a sample size of 317 subjects (167 male and 150 female) from four provinces of Iran. A pilot preliminary test for assessing test-retest reliability on ten body dimensions using the Intraclass Correlation Coefficient (ICC2 :1)  was performed. Descriptive statistics were reported based on gender and independent samples t-tests to compare the anthropometric dimensions of both genders and age. RESULTS: Results indicated higher dimensions in males, except for hip-breadth (p = 0.87). In all subjects, increasing age corresponded with: decreased standing shoulder height, eye height, and elbow height; and with sitting height and sitting knee height; while hip-breadth increased. Reliability was acceptable (ICC2.1 >0.88). In the elderly, as with adult subjects, there are significant gender differences in body dimensions, and this should be considered in equipment and system design. Furthermore, this study demonstrated both genders differences and the consequences of aging. CONCLUSIONS: From this pilot data, product designers can consider the anthropometric characteristics for elderly Iranian subjects for equipment and system design.

Effects of handle characteristics of manual hand tools on maximal torque exertions: a literature review.

The present study was conducted to review the literature on the effects of handle characteristics of manual hand tools including handle diameter, shape and material on forearm supination/pronation, wrist flexion/extension and wrist ulnar/radial deviation torque strengths to assist ergonomists and designers in developing guidelines to improve workstations and hand tool designs. Twenty-seven papers meeting the inclusion criteria were reviewed. The study provides different points that can be applied to improve the design of hand tools with an emphasis on handle diameter, shape and material, and highlights various methodological issues including interactions among variables affecting maximum torque strength, posture, torque exertion using one or two hands, torque exertions in multiple anatomical axes, using gloves, upper extremity anthropometry and test protocols, which should be considered in future research.

The new "Tehran Back Belt": Design then testing during a simulated sitting task improved biomechanical spine muscle activity.

Background: Spinal load and muscle activity in occupation settings is an area of increasing concern. Regarding technological advancements, in diverse occupations the spinal loads have increased through constrained seated postures. Back belts are consequently used in prophylactic and conservative management of occupational low back pain (LBP) in two distinct settings, prevention in industry, and treatment in LBP management. Industrial sites utilize belts for LBPprophylaxis on a large scale with their design and user experience (UE) influencing both the effectiveness and the workers' compliance. This pilot study aims at determining the effectiveness of the new Tehran Back Belt (TBB) and assesses both UE and biomechanical effect (BE) on para-spinal muscle activity in healthy subjects. Methods: A pretest-posttest study. Stage-1, design and fabrication of the TBB. Stage-2, the UE of the designed belt evaluated in healthy volunteers (n=30) via a checklist. The BE was determined from the level of lumbar extensor and trunk flexor muscle activity gauged during two test conditions of sitting posture (with and without belt) over 35-minute periods. Results: Most subjects (>90%) reported high 'ease of use' and 'comfort' while wearing the TBB.The BE statistical analysis showed significantly reduced EMG activity levels for the longissimus(P = 0.012, η2=0.24), rectus abdominis (P=0.024, η2=0.18) and internal oblique (P=0.001,η2=0.44) muscles in belt-use conditions. Conclusion: Decreased muscle activity while using the TBB is potentially advantageous for workers as spinal muscle activity is significantly reduced. Further investigations for longer duration effects and during real work office-based activities are warranted.

Influences of gender, hand dominance, and anthropometric characteristics on different types of pinch strength: A partial least squares (PLS) approach.

The relationships of demographic and anthropometric characteristics (17 dimensions related to the hand, wrist, and arm) with four different pinch strengths (lateral pinch, key pinch, three-jaw chuck pinch and tip-to-tip pinch strengths) were evaluated among 196 (96 males and 100 females) young adults aged 19-30 years. For both dominant and non-dominant hands, the lateral pinch was greatest, followed by the key pinch, three-jaw chuck pinch and tip-to-tip pinch strengths. Mean pinch strengths of the dominant and non-dominant hands of females varied between 62%-78% and 61%-73% of those exerted by males, respectively. Strength of the dominant hand was 5.3%-7.5% stronger than of that of the non-dominant hand, with this difference being generally higher in females than in males. Hand length and forearm length showed the strongest correlation with all types of pinch strengths exerted by both the dominant and non-dominant hands. In the partial least squares analysis, 10 out of 17 anthropometric indices including hand length, forearm length, arm length, middle finger width, thumb length, index finger width, thumb width, wrist depth, palm depth and index finger depth had considerable loadings in the extracted component, explaining 37% of the total variance. These findings can fill the gap in the strength data, or used by health professionals and designers in the field.

Association of musculoskeletal disorders and workload with work schedule and job satisfaction among emergency nurses.

BACKGROUND: The emergency department is a highly demanding work environment, considered by high workload and stress. The impact of work-related factors on musculoskeletal disorders (MSDs) in emergency nurses (ENs) are not yet well understood. We investigated the association of MSDs and workload with work schedule (permanent day and night work) and job satisfaction in ENs. METHOD: Data were collected through a questionnaire including individual and work-related factors, workload (National Aeronautics and Space Administration-Task Load Index [NASA-TLX]) and MSDs (Standardized Nordic Questionnaire) from 380 ENs in five hospitals. RESULTS: The findings revealed that work schedule and job satisfaction levels were significantly associated with the MSDs in different body regions. Work schedule was significantly related to physical demand, performance, frustration, and overall workload, whereas it was not to the mental and temporal demands and effort. Job satisfaction level was negatively associated with mental demand and frustration. A high prevalence of musculoskeletal problems, particularly in knees, upper back, lower back, neck and shoulders were found. CONCLUSION: MSDs are highly prevalent among ENs involved in night work and with low job satisfaction levels. The results are discussed in terms of their implications for emergency hospital nurses. The findings can help to better understand the working conditions and emphasize the need for ergonomic interventions in order to reduce MSDs and workload. Also, the study findings highlight the importance of mental aspects of workload in this occupational group.

Cross-cultural adaptation, validity, and reliability of the Persian version of the spine functional index.

BACKGROUND: There are various instruments and methods to evaluate spinal health and functional status. Whole-spine patient reported outcome (PRO) measures, such as the Spine Functional Index (SFI), assess the spine from the cervical to lumbo-sacral sections as a single kinetic chain. The aim of this study was to cross-culturally adapt the SFI for Persian speaking patients (SFI-Pr) and determine the psychometric properties of reliability and validity (convergent and construct) in a Persian patient population. METHODS: The SFI (English) PRO was translated into Persian according to published guidelines. Consecutive symptomatic spine patients (104 female and 120 male aged between 18 and 60) were recruited from three Iranian physiotherapy centers. Test-retest reliability was performed in a sub-sample (n = 31) at baseline and repeated between days 3-7. Convergent validity was determined by calculating the Pearson's r correlation coefficient between the SFI-Pr and the Persian Roland Morris Questionnaire (RMQ) for back pain patients and the Neck Disability Index (NDI) for neck patients. Internal consistency was assessed using Cronbach's α. Exploratory Factor Analysis (EFA) used Maximum Likelihood Extraction followed by Confirmatory Factor Analysis (CFA). RESULTS: High levels of internal consistency (α = 0.81, item range = 0.78-0.82) and test-retest reliability (r = 0.96, item range = 0.83-0.98) were obtained. Convergent validity was very good between the SFI and RMQ (r = 0.69) and good between the SFI and NDI (r = 0.57). The EFA from the perspective of parsimony suggests a one-factor solution that explained 26.5% of total variance. The CFA was inconclusive of the one factor structure as the sample size was inadequate. There were no floor or ceiling effects. CONCLUSIONS: The SFI-Pr PRO can be applied as a specific whole-spine status assessment instrument for clinical and research studies in Persian language populations.

Cross-Cultural Adaptation, Validity, and Reliability of the Persian Version of the Orebro Musculoskeletal Pain Screening Questionnaire.

STUDY DESIGN: Observational study. PURPOSE: To cross-culturally translate the Orebro Musculoskeletal Pain Screening Questionnaire (OMPQ) into Persian and then evaluate its psychometric properties (reliability, validity, ceiling, and flooring effects). OVERVIEW OF LITERATURE: To the authors' knowledge, prior to this study there has been no validated instrument to screen the risk of chronicity in Persian-speaking patients with low back pain (LBP) in Iran. The OMPQ was specifically developed as a self-administered screening tool for assessing the risk of LBP chronicity. METHODS: The forward-backward translation method was used for the translation and cross-cultural adaptation of the original questionnaire. In total, 202 patients with subacute LBP completed the OMPQ and the pain disability questionnaire (PDQ), which was used to assess convergent validity. 62 patients completed the OMPQ a week later as a retest. RESULTS: Slight changes were made to the OMPQ during the translation/cultural adaptation process; face validity of the Persian version was obtained. The Persian OMPQ showed excellent test-retest reliability (intraclass correlation coefficient=0.89). Its internal consistency was 0.71, and its convergent validity was confirmed by good correlation coefficient between the OMPQ and PDQ total scores (r=0.72, p<0.05). No ceiling or floor effects were observed. CONCLUSIONS: The Persian version of the OMPQ is acceptable for the target society in terms of face validity, construct validity, reliability, and consistency. It is therefore considered a useful instrument for screening Iranian patients with LBP.