Effects of work surface and task difficulty on neck–shoulder posture and trapezius activity during a simulated mouse task

Objectives. The purpose of this study is to evaluate the influence of the work surface and task difficulty on the head, upper back and upper arm postures and activity of the descending trapezius during a simulated mouse task. Methods. Healthy female university students (N?=?15) were evaluated. The work surface was positioned at elbow height (EH) and above elbow height (AEH) and the task difficulty was set at low (LD) and high (HD) levels. The postures were recorded by inclinometers. Trapezius activity was normalized by the maximum voluntary isometric contraction (MVIC). Results. Significantly higher head flexion was found at EH compared to the AEH condition, with an average difference of 2°–5° at the same difficulty level. The HD task significantly increased head (3°–6°) and upper back flexion (6°–7°) at the same table height. For upper arm elevation and trapezius activation, the AEH condition presented higher upper arm elevation (about 6°–8°) and trapezius activity (0.8–1.4% of MVIC), regardless of the difficulty level of the task. Conclusions. Head posture was influenced by the table height and task difficulty; the upper back posture by high difficulty; and upper arm posture and trapezius activity were only influenced by table height.     

Effects of physical exercise on musculoskeletal disorders,stress and quality of life in workers

Background. The effect of physical exercise in the workplace (PEW) on health promotion of workers is contradictory. Objective. To evaluate the effects of the PEW in musculoskeletal disorders (MSDs), perception of stress and quality of life in workers. Methods. The participants were divided into two groups: control group (n?=?46) including non-participant workers of the PEW program, and PEW group (n?=?50) including workers who regularly participate in the exercise program. All workers answered the Nordic general questionnaire, the perceived stress scale and the quality-of-life questionnaire. Results. The PEW group reported a lower prevalence of MSDs for the trunk in the last 7 days and 12 months (p?=?0.021 and p?=?0.001, respectively), and for the upper limbs in the last 12 months (p?=?0.001) compared with the control group. The results for the perception of stress and quality of life showed no significant differences between the groups. Conclusion. PEW is a potential method to reduce MSDs in workers, but it was not efficient in reducing stress levels or improving the quality of life of the workers.     

Occupational noise exposure and hearing defects among sawmill workers in the south of Thailand

The aim of this study was to investigate occupational noise exposure and hearing defects among sawmill workers in the south of Thailand. Seven hundred sawmill workers participated, of which 335 (47.9%) were male. The mean age of the sawmill workers was 33.5 years (SD 10.2), and more than 60% were <35 years old; 75.1% of the workers had less than 5 years of work experience. Only about one in four workers (25%) had been trained in use of personal protective equipment (PPE), and half of the participants never or rarely wore PPE while working. The prevalence rate of noise-induced hearing loss (NIHL) was 22.8% (N?=?42). Male workers had significantly higher risk than female workers (odds ratio [OR]?=?2.21). Workers aged older than 25 years had significantly higher risks for NIHL (OR?=?3.51–12.42) than workers younger than 25 years. Sawing workers had higher risk for NIHL than office workers (OR?=?3.07).     

An experimental study to evaluate musculoskeletal disorders and postural stress of female craftworkers adopting different sitting postures

This study aimed to evaluate musculoskeletal disorders (MSDs) and postural stress among female craftworkers. The study was carried out on 75 adult female craftworkers in different districts of West Bengal. The prevalence of MSDs, body part discomfort (BPD) rating and body joint angles of the workers were evaluated with standard methods. Electromyography (EMG) of the shoulder and back muscles was recorded with the BIOPAC system. The prevalence of MSDs, BPD rating and deviation of joint angle were comparatively lower in the case of sitting on the floor with folded legs than squatting and sitting on the floor with stretched legs postures. The EMG and rms values of the shoulder and back muscles were comparatively lower in this posture. Therefore, it was concluded that sitting on the floor with folded legs was less hazardous and it imposed less postural stress in comparison to other sitting postures.     

Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n?=?40) and welder assistants (n?=?25) from welding units as the exposed group, and office workers (n?=?44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p?p?M (SD)?=?54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.     

Psychosocial and ergonomic survey of office and field jobs in a utility company

Introduction. The effect of different kinds of work on the psychosocial assessment of workers under the same management and organizational environment is investigated. Methods. A voluntary assessment in a utility company was carried out using the short version of the Copenhagen psychosocial questionnaire (CoPsoQ) on two occasions, 1.5 years apart. Initially, 25 office workers (11 men and 14 women) participated, while 14 of those workers (8 women and 6 men) participated in the second assessment together with 32 field workers. The sewage, water treatment and maintenance workers, totaling 32 men, also participated in a field ergonomics assessment using the Washington State Department of Labor and Industries field work ergonomic checklist. Results. The longitudinal outlook was fairly stable, with sustained severe scores in many CoPsoQ subscales and intensification of severity of workers’ control over work and esteem for men. A significantly higher esteem score resulted for field rather than office workers. Workers subjected to foul odors showed similar severity of psychosocial factors. Discussion. For most psychosocial dimensions, the organizational design and management system in place, as well as the overall cultural environment in which it operates, create a much stronger and more decisive impact than job-specific factors.     

Measuring limitations in activities of daily living: a population-based validation of a short questionnaire

Purpose. A newly developed questionnaire assessing limitations in activity of daily living (LADL–Q) that should improve assessment of LADL is tested in a large population-based validation study. Methods. This survey was paper-based. Overall, 16,634 individuals who were representative of the working population in the German-speaking part of Switzerland participated in the study. Item analysis was used the final version of the LADL–Q to four items per subscale that correspond to potential problems in three body regions (back and neck, upper extremities, lower extremities). Analysis included tests for reliability, internal consistency, dimensionality and convergent validity. Results. Test–retest reliability coefficients after 2 weeks ranged from 0.82 to 0.99 (Mdn?=?0.87), with no item having a coefficient below 0.60. The median item-total coefficients ranged between moderate and good. Correlation coefficients between LADL–Q subscales and three validated clinical instruments (Western Ontario and McMaster Universities osteoarthritis index, shoulder pain disability index, Oswestry) ranged from 0.63 to 0.81. In structural equation modeling the three subscales were significantly related with two important outcomes in occupational rehabilitation: self-reported general health and daily task performance. Conclusion. The new LADL–Q is a brief, reliable and valid tool for assessment of LADL in studies on musculoskeletal health.     

Investigation of work-related musculoskeletal disorders among male kitchen workers in South India

Objective. This study aims to quantify the prevalence of work-related musculoskeletal disorders (MSDs) and risks among male kitchen workers in the catering industry. Method. Data were collected with the help of the Nordic musculoskeletal questionnaire and by direct observations. Results. In total, 114 male kitchen workers from various hostels of a college in South India were considered for this study. The average age and mean years of employment of the workers are 26.4 (SD 7.7) and 7.8 respectively. The statistical analysis carried out reveals that 67.5% of male kitchen workers reported MSDs during the past 12 months. The highest prevalence rate has been found in the lower back (65.8%) and shoulder region (62.3%). Among different categories of kitchen work analyzed, it is evident that chief cooks suffer more from MSDs (79.2%) than assistant cooks (74.3%) and kitchen aides (30.0%). Workers in the older group, i.e., ≥41 years, and workers with 6–10 years of experience suffer with higher risk of MSDs, i.e., 93.9% and 87.5%, respectively. Conclusion. The male kitchen workers who participated in this research were found to possess both MSDs and ergonomic hazards.     

Perceived Discomfort and Electromyographic Activity of the Upper Trapezius While Working at a VDT Station

Ten female participants performed work at a video display terminal (VDT) station over a whole working day. Subjective local muscular fatigue was evaluated by means of the Category Ratio 10 scale. Electromyographic activity of the upper right and left trapezius was measured. A comparison was made between 5 participants who had previous complaints and 5 participants who reported no musculoskeletal problems in the shoulder-neck region. The subjective scores for the shoulder differed significantly between the two groups, being higher for the group with complaints. Both groups showed a decrease in discomfort after the lunch break. The activity of the trapezius increased significantly for both groups, in a more pronounced way for the group with disorders. Although it is found in literature that VDT work is a task with very low static loads, it seems from this study that the EMG activity increase can be an indication of muscle fatigue: More effort was required to accomplish the same VDT task at the end of the day.     

Evaluating the usability of a commercial cooling vest in the Hong Kong industries

Objective. The provision of appropriate personal cooling vests is recognized as an effective measure to combat heat stress. However, personal cooling vests are not widely implemented in the Hong Kong industries. The current study aims to evaluate the usability of a hybrid cooling vest that is associated with the success of its application in industrial settings. Methods. A self-administrated questionnaire focusing on 10 subjective attributes of cooling effect, ergonomic design and usability of a hybrid cooling vest was administered with 232 occupational workers in the construction, horticultural and cleaning, airport apron services and kitchen and catering industries. Results. A structural equation model estimated by analysis of moment structures was constructed to evaluate the usability of the cooling vest, as influenced by cooling effect and ergonomic design. Results showed that cooling effect (path coefficient?=?0.69, p?p?Conclusions. The structural equation model is feasible to examine the complex nature of the structural relationships among the subjective perceptions of personal cooling vests. The empirical findings furnish sound evidence for further optimization of the hybrid cooling vest in terms of cooling effect and ergonomic design for occupational workers.     

Will Musculoskeletal,Visual and Psychosocial Stress Change for Visual Display Unit (VDU) Operators When Moving From a Single-Occupancy Office to an Office Landscape?

This study investigated the effect of moving from single-occupancy offices to a landscape environment. Thirty-two visual display unit (VDU) operators reported no significant change in visual discomfort. Lighting conditions and glare reported subjectively showed no significant correlation with visual discomfort. Experience of pain was found to reduce subjectively rated work capacity during VDU tasks. The correlation between visual discomfort and reduced work capacity for single-occupancy offices was r_s = .88 (p = .000) and for office landscape r_s = .82 (p = .000). Eye blink rate during habitual VDU work was recorded for 12 operators randomly selected from the 32 participants in the office landscape. A marked drop in eye blink rate during VDU work was found compared to eye blink rate during easy conversation. There were no significant changes in pain intensity in the neck, shoulder, forearm, wrist/hand, back or headache (.24 < p < .67). Pain levels in different body areas were significantly correlated with reduced work capacity, .77 < r_s < .99 (p = .000).     

Injury-related hospital admission of female firefighters in South Korea

Purpose. The main objective of this study was to ascertain whether injury-related hospital admission in all South Korea female firefighters is greater than that in the general population. Methods. To perform this comparison, the standardized admission ratios (SARs) and their 95% confidence intervals (CIs) were calculated by person-years and mortality computation software. Results. Compared to the general population, the SARs for overall injury (SAR?=?1.57, 95% CI [1.24, 1.96]) and for injury to the lower back (SAR?=?2.78, 95% CI [1.81, 4.07]) in the female firefighters were significantly higher. The SARs for injury to the knee (SAR?=?2.48, 95% CI [1.18, 4.55]) in emergency medical services (EMS) workers were significantly higher than those in the general population. Conclusions. Our study shows that the SARs of overall injury and injury to the lower back in female firefighters and knee injury in the EMS were significantly higher than those in the general population. Further studies are needed to protect the lower back of firefighters and the knees of EMS.     

Impact of posture and upper-limb muscle activity on grip strength

Purpose. The current research was carried out to determine grip strength (GS) with change in posture and upper-limb muscle activity of manual workers and investigate the impacts of these changes. Methods. For the current research, 120 male and 80 female participants were selected and GS was assessed using a digital hand grip dynamometer in various conditions. Results. The outcomes showed that male participants had higher GS as compared to female participants. Maximum GS was found in a standing posture with the fixed forward shoulder at 45°, elbow at 90° and a neutral position of the wrist and forearm for all participants. Conclusions. Higher values of GS were attained in standing postures which may result in attainment of higher performance levels by the workers. The outcomes justify the importance of correct postures during manual work in industries employing traditional methods.     

Upper trapezius fatigue in carpet weaving: the impact of a repetitive task cycle

Introduction. Shoulder disorders are one of the most prevalent musculoskeletal disorders among carpet weavers. The most important cause of these disorders is muscle fatigue. The aim of the present study is to investigate the effect of carpet weaving characteristics on upper trapezius (UTr) muscle fatigue during a task cycle. Method. In this cross-sectional study, 9 women and 3 men participated. During an 80-min cycle of carpet weaving, a times-series model was applied to assess electromyography amplitude and frequency changes. Result. According to the joint analysis of electromyogram spectrum and amplitude method, the participants experienced 0% force decrease, 0.9% recovery, 18% force increase and 72% fatigue in the left UTr. Furthermore, the rates of force decrease, recovery, force increase and fatigue in the right UTr were 18%, 18%, 18% and 45%, respectively. Fatigue in the right and the left UTr was reported to be the dominant state during one carpet weaving task cycle. Conclusion. Task cycle appears to have a significant impact on UTr fatigue in participants, and UTr fatigue can be considered a serious risk factor in shoulder musculoskeletal disorders. Hence, further studies should focus on better workstations and work–rest periods during various subtasks.     

Postural and Muscular Responses While Viewing Different Heights of Screen

This study aimed to examine the effects of visual display terminal (VDT) viewing angle on human postural angle and muscular activity. The participants’ neck, thoracic bending, and trunk inclination angles; and the activity of sternocleidomastoid, trapezius, splenius capitis, and erector spinae at 5 viewing angles (+40°, +20°,0°, –20°, and –40°) of a VDT screen were collected for 1 min. This study showed that neck and thoracic bending angles increased with viewing angle, while viewing angle did not significantly affect trunk inclination angle. In addition, the activity of trapezius and erector spinae increased when viewing a higher or lower VDT screen height compared with viewing a horizontal VDT screen height; however, the activity of splenius capitis decreased with viewing angle.     

Effect of automated versus manual emergency braking on rear seat adult and pediatric occupant precrash motion

Abstract

Objective: Emergency braking can potentially generate precrash occupant motion that may influence the effectiveness of restraints in the subsequent crash, particularly for rear-seated occupants who may be less aware of the impending crash. With the advent of automated emergency braking (AEB), the mechanism by which braking is achieved is changing, potentially altering precrash occupant motion. Further, due to anatomical and biomechanical differences across ages, kinematic differences between AEB and manual emergency braking (MEB) may vary between child and adult occupants. Therefore, the objective of this study was to quantify differences in rear-seated adult and pediatric kinematics and muscle activity during AEB and MEB scenarios.

Methods: Vehicle maneuvers were performed in a recent model year sedan traveling at 50?km/h. MEB (acceleration ～1?g) was achieved by the driver pressing the brake pedal with maximum effort. AEB (acceleration ～0.8?g) was triggered by the vehicle system. Inertial and Global Positioning System data were collected. Seventeen male participants aged 10–33 were restrained in the rear right passenger seat and experienced each maneuver twice. The subjects’ kinematics were recorded with an 8-camera 3D motion capture system. Electromyography (EMG) recorded muscle activity. Head and trunk displacements, raw and normalized by seated height, and peak head and trunk velocity were compared across age and between maneuvers. Mean EMG was calculated to interpret kinematic findings.

Results: Head and trunk displacement and peak velocity were greater in MEB than in AEB in both raw and normalized data (P?≤?.01). No effect of age was observed (P?≥?.21). Peak head and trunk velocities were greater in repetition 1 than in repetition 2 (P?≤?.006) in MEB but not in AEB. Sternocleidomastoid (SCM) mean EMG was greater in MEB compared to AEB, and muscle activity increased in repetition 2 in MEB.

Conclusions: Across all ages, head and trunk excursions were greater in MEB than AEB, despite increased muscle activity in MEB. This observation may suggest an ineffective attempt to brace the head or a startle reflex. The increased excursion in MEB compared to AEB may be attributed to differences in the acceleration pulses between the 2 scenarios. These results suggest that AEB systems can use specific deceleration profiles that have potential to reduce occupant motion across diverse age groups compared to sudden maximum emergency braking applied manually.     

Assessing the performance of motorcyclists’ impact protectors in simulated ATD knee and shoulder impacts

Objective: Fractures are a common injury among motorcycle riders and can have serious health implications. Impact protection (IP) has been designed to help prevent fractures, yet there are conflicting opinions as to whether this IP does in fact help prevent fractures in real-world crashes. This work aimed to (1) use simulated dummy impacts to examine whether existing types of IP could reduce the force transferred to the underlying bone to below fracture tolerance levels and (2) investigate whether current European Standard (EN 1621-1) test procedures for impact protectors designed for motorcyclists are sufficient to ensure fracture protection.

Method: Twenty-three shoulder and 7 knee IP specimens were tested using a 23-kg impactor contacting axially along the clavicle and femur of an anthropomorphic test device (ATD) at an energy level corresponding to the fracture tolerance of these bones. Sixteen IP specimens were the same as those worn by motorcycle riders involved in crashes where injury outcome was known (knee: n?=?3; shoulder: n?=?13) and the IP had been previously tested to EN 1621-1. Other IP tested represented a wide range of IP available for purchase at a motorcycle accessory store. Double and triple layers of IP were also tested. Energy attenuated during the dummy impacts was compared to energy attenuated when tested to EN 1621-1.

Results: Of the 23 shoulder IP tested, the average percentage reduction of transferred force to the shoulder from the baseline test was 7.6?±?4.8%. The percentage reduction of transferred force to the knee from the baseline was 43.9?±?7.5%. The entire group of knee IP tested reduced the transferred force to the knee to below the 10-kN injury threshold for the femur. There was a positive but nonsignificant correlation between the ATD test and the EN 1621-1 impact test performance, suggesting that the European standard test method likely provides a good indication of IP performance. However, given the low correlation coefficient, the relationship between IP performance in the European standard test method and injury protection remains unclear.

Conclusion: Though the energy attenuation test method in the European standard may be an appropriate approach, distinct differences in injury protection performance observed between knee and shoulder IP indicate that there may be a need for different performance criteria for IP designated to protect different body regions.     

Effects of Ergorest® Arm Supports on Muscle Strain and Wrist Positions During the Use of the Mouse and Keyboard in Work With Visual Display Units: A Work Site Intervention

The effects of Ergorest^® arm supports on wrist angles and musculoskeletal strain in the neck-shoulder-arm region and electrical activity in the shoulder and arm muscles were studied during typing or the use of the mouse in work with a visual display unit (VDU). Twenty-one women were randomized into 3 groups (1 arm support, 2 arm supports, and control). Measurements were carried out before and after the 6-week intervention. The wrist extension of the mouse hand, the muscle activity of the trapezius muscle, and the subjective discomfort ratings indicated that 2 arm supports were better than 1 in work with a mouse. The Ergorest^® arm support alleviates muscle and joint strain in VDU work when used for both arms.     

An assessment of safety climate,job satisfaction and turnover intention relationships using a national sample of workers from the USA

The association between safety climate, job satisfaction and turnover intention has not been thoroughly researched. This research is needed so that safety researchers and practitioners can begin to delineate the impact of safety on organizational and business outcomes. A path analysis was completed using data from a national sample of workers from the USA (n?=?1525). The overall fit of the model was excellent and analyses determined that both training and resource adequacy positively affected safety climate and job satisfaction. Safety climate also positively influenced job satisfaction. Both safety climate and job satisfaction were negatively associated with respondents’ turnover intention. In the study, the relationship between job satisfaction and turnover intention is reiterated in a sample of workers across many industries. This study is novel because it is one of the first studies to confirm that turnover intention is reduced with increased safety climate in a diverse sample of workers.     

Duty hours and incidents in flight among commercial airline pilots

Introduction. Working long duty hours has often been associated with increased risk of incidents and accidents in transport industries. Despite this, information regarding the intermediate relationship between duty hours and incident risk is limited. This study aimed to test a work hours/incident model to identify the interplay of factors contributing to incidents within the aviation industry. Methods. Nine hundred and fifty-four European-registered commercial airline pilots completed a 30-item survey investigating self-report attitudes and experiences of fatigue. Path analysis was used to test the proposed model. Results. The fit indices indicated this to be a good fit model (χ²?=?11.066, df?=?5, p?=?0.05; Comparative Fit Index?=?0.991; Normed Fit Index?=?0.984; Tucker–Lewis Index?=?0.962; Root Mean Square of Approximation?=?0.036). Highly significant relationships were identified between duty hours and sleep disturbance (r?=?0.18, p?r?=?0.40, p?r?=?0.43, p?Discussion. A critical pathway from duty hours through to self-reported incidents in flight was identified. Further investigation employing both objective and subjective measures of sleep and fatigue is needed.