Continuous assessment of back and upper arm postures by long-term inclinometry in carpet weavers

Awkward back and shoulder postures have been suggested to be a cause of back and shoulder discomfort in carpet weavers. This study aimed at continuous assessment of the upper arm and back postures and estimation of biomechanical load subtasks using inclinometers during 4 h.Median of trunk flexion angle in weavers was 18° and 13° during knotting and compacting subtasks, respectively. The weavers worked with arms elevated greater than 45° for %4.5 of the work time. The average cumulative compression load for males and females were estimated at 22 MN-S and 13 MN-S, respectively.In addition to poor workstation design, constrained posture of the trunk and low elevation and velocity for both arms may be the main risk factors for developing fatigue and disorders in the back and shoulder regions among carpet weavers. Therefore, any ergonomic interventions should be focused on reducing trunk flexion and the constrained postures of weavers.     

Accuracy and validity of observational estimates of shoulder and elbow posture

This study investigated the accuracy of video-based observational posture analysis for the elbow and shoulder. Posture analyses were conducted by 28 ergonomists for four jobs presented on a traditional VHS format video recording. Estimates of posture from the observational-based methods were compared with values measured directly with an optical motion capture system. Ergonomists used categorical posture scales and a continuous visual analog scale to estimate the peak and most frequently occurring or average posture for each job. Use of a three-category scale resulted in misclassifications of peak and most frequently occurring elbow and shoulder posture with a probability averaging 30.1%. With the six-category posture scale this average probability of misclassification increased to 64.9%. Using a continuous visual analog scale peak shoulder elevation was the only posture for which the average error among ergonomists' estimates was significantly different from zero (p<0.05). Correlations between the estimated postures and measured postures were higher and statistically significant (p<0.05) for elbow flexion and shoulder elevation (r2 between 0.45 and 0.66) but were considerably lower and not significant (r2 between 0.03 and 0.18) for the peak and average horizontal shoulder abduction. Ergonomists' estimates of the temporal distribution of shoulder posture, indicating the duration severity of the posture, appeared to be biased such that the percentage of the cycle time in each posture category was estimated as more uniformly distributed than the measured values indicated.     

Inter-rater reliability of output measures for a posture matching assessment approach: a pilot study with food service workers

Despite the ongoing health problem of repetitive strain injuries, there are few tools currently available for ergonomic applications evaluating cumulative loading that have well-documented evidence of reliability and validity. The purpose of this study was to determine the inter-rater reliability of a posture matching based analysis tool (3DMatch, University of Waterloo) for predicting cumulative and peak spinal loads. A total of 30 food service workers were each videotaped for a 1-h period while performing typical work activities and a single work task was randomly selected from each for analysis by two raters. Inter-rater reliability was determined using intraclass correlation coefficients (ICC) model 2,1 and standard errors of measurement for cumulative and peak spinal and shoulder loading variables across all subjects. Overall, 85.5% of variables had moderate to excellent inter-rater reliability, with ICCs ranging from 0.30–0.99 for all cumulative and peak loading variables. 3DMatch was found to be a reliable ergonomic tool when more than one rater is involved.     

The effects of shoulder posture on neck and shoulder musculoskeletal loading and discomfort during smartphone usage

While using their smartphone, users tend to adopt awkward neck and shoulder postures for an extended duration. Such postures impose the risk of MSDs on those body parts. Numerous studies have been undertaken to examine neck posture; however, few studies have investigated shoulder postures. This study examined various shoulder postures during smartphone use and their effect on neck and shoulder kinematics, muscle loading, and neck/shoulder discomfort. Thirty-two asymptomatic young adult smartphone users randomly performed texting tasks for 3 min at four different shoulder flexion angles (15°, 30°, 45°, and 60°), while maintained a neck posture in the neutral position (0° neck flexion angle). Measures were taken of neck and shoulder muscle activity of the cervical erector spinae (CES), anterior deltoid (AD), upper trapezius (UT) and lower trapezius (LT), and kinematic data (angle, distance and gravitational moment). Results showed AD and LT muscle activity significantly increased when the shoulder flexion angle increased with an opposite effect on CES and UT. A recommended shoulder posture was identified as 30° flexion, as this yielded the best compromise between activation levels of the four muscles studied. This angle also induced the lowest neck/shoulder discomfort score. The findings suggest smartphone users hold their device at approximately 30° shoulder flexion angle with their neck in a neutral posture to reduce the risk of shoulder and neck musculoskeletal disorders when smartphone texting.Relevance to industrySmartphone use in the manufacturing and service industries is an integral part of work and useful means of communication tool. Awkward postures during extensive smartphone use impose an increased risk of both neck and shoulder musculoskeletal disorders. Shoulder flexion angles need consideration when making recommendations about safe work postures during smartphone use.     

Working conditions of Iranian hand-sewn shoe workers and associations with musculoskeletal symptoms

The working conditions and the prevalence of self-reported musculoskeletal symptoms among 180 Iranian hand-sewn shoe workers were evaluated in this cross-sectional study. Data were collected using both questionnaire (for assessing musculoskeletal symptoms and associated risk factors) and direct observations of posture (by the Rapid Upper Limb Assessment [RULA] method). The prevalence and severity of symptoms was very high among the study population. The mean RULA grand score of 6.2 indicates that in most cases the workers' postures at their workstations need to be investigated and some changes are required immediately. Multiple logistic regression models indicated that the job experience, daily working hours, duration of continuous work without breaks, feeling pressure due to work and working postures were significantly associated with musculoskeletal symptoms of different body regions. The results are discussed in terms of their implications for hand-sewing tasks. These findings can help to better understand the working conditions of those jobs involving hand-sewing operation and highlight the potential for ergonomic interventions to reduce musculoskeletal symptoms among these working groups.

Practitioner Summary: Working conditions of hand-sewn shoe workers and their musculoskeletal symptoms were investigated. The prevalence and severity of musculoskeletal symptoms was very high among the study population. Poor working postures, feeling pressure due to work, long duration of work without breaks and prolonged daily working hours were positively associated with musculoskeletal symptoms.     

The effect of posture category salience on decision times and errors when using observation-based posture assessment methods

Observation-based posture assessment methods (e.g. RULA, 3DMatch) require classification of body postures into categories. This study investigated the effect of improving posture category salience (adding borders, shading and colour to the posture categories) on posture selection error rates and decision times of novice analysts. Ninety university students with normal or corrected normal visual acuity and who were not colourblind, were instructed to select posture categories as quickly and accurately as possible, in five salience conditions (Plain (no border, no shading, no colour); Grey Border; Red Border; Grey Shading (GS) and Red Shading (RS)) for images presented in randomised blocks (240 classifications made by each participant) on a computer interface. Participants responded quickest in the Border conditions, classifying postures about 5% faster than in the Plain condition. Coloured diagrams significantly reduced posture classification errors by approximately 1.5%. Overall, the best performance, based on both error rate and decision time combined, resulted from incorporating a Grey Border to the posture category diagrams; a simple enhancement that could be made to most current observation-based posture assessment tools.

Practitioner Summary: The salience of posture diagrams used in observation-based posture assessment tools was evaluated with respect to analyst error rates and decision times. The best performance resulted from incorporating a grey border to the posture diagrams; a simple enhancement that can be made to most current observation-based posture assessment tools.     

Variation in upper limb posture and movement during word processing with and without mouse use

Work postures and movements of the upper limb were analysed for 12 ‘mouse’ operators and 12 ‘non-mouse’ computer operators employed in word-processing work. Measurements were carried out during correction of a given text. ‘Mouse’ operators spent 64% of the working time with the operative wrist deviating more than 15° towards the ulnar side, while ‘non-mouse’ operators spent 96% of the time with the corresponding wrist in neutral position towards radial deviation. The rotation in the shoulder was at all times in neutral position towards inward rotation for ‘non-mouse’ operators, while ‘mouse’ operators worked 81% of the time with the shoulder rotated outward more than 30°. ‘Mouse’ operators corrected a longer text during the given time. Our observations showed long periods of strenuous working postures for ‘mouse’ operators compared to ‘non-mouse’ operators. We believe that further investigations need to be carried out on the effects of word-processing techniques and to develop ergonomic work station designs for the ‘mouse’ and other non-keyboard input devices.     

Effects of work surface height on muscle activity and posture of the upper extremity during simulated pipetting

In order to examine the effects of work surface height (WSH) on muscle activity, posture and discomfort during simulated pipetting, an experimental study was conducted using electromyography, electrogoniometry, video techniques and also qualitative data. The experimental design consisted of one independent variable (WSH with six heights) and 13 dependent variables. The levels of muscle strain and discomfort were significantly lower at the shoulder when the WSHs were low but thumb muscle activities and neck flexion levels were markedly higher at these WSHs compared to higher WSHs. To reduce shoulder strain, without raising thumb and neck strain beyond acceptable limits, the findings suggest that the height of a laboratory workbench should be at the level of the pipette tip when held in a standing position with the hand at elbow height. It was also found that pipetting should not be done in a seated posture.

Practitioner Summary: An experimental study was conducted to examine the effects of work surface height on upper extremity muscle activity, posture and discomfort during simulated pipetting. The findings suggest that the laboratory workbench height should be at the pipette-tip level when held in a standing position with the hand at elbow height.     

Comparison between low-cost marker-less and high-end marker-based motion capture systems for the computer-aided assessment of working ergonomics

The paper deals with the comparison between a high-end marker-based acquisition system and a low-cost marker-less methodology for the assessment of the human posture during working tasks. The low-cost methodology is based on the use of a single Microsoft Kinect V1 device. The high-end acquisition system is the BTS SMART that requires the use of reflective markers to be placed on the subject's body. Three practical working activities involving object lifting and displacement have been investigated. The operational risk has been evaluated according to the lifting equation proposed by the American National Institute for Occupational Safety and Health. The results of the study show that the risk multipliers computed from the two acquisition methodologies are very close for all the analysed activities. In agreement to this outcome, the marker-less methodology based on the Microsoft Kinect V1 device seems very promising to promote the dissemination of computer-aided assessment of ergonomics while maintaining good accuracy and affordable costs.     

The predictive validity of the RSI QuickScan questionnaire with respect to arm,shoulder and neck symptoms in computer workers

The aim of this study was to determine whether results from the RSI QuickScan questionnaire on risk factors for arm, shoulder and neck symptoms can predict future arm, neck and shoulder symptoms in a population of computer workers. For this prospective cohort study, with a follow-up of 24 months, 3383 workers who regularly worked with a computer were approached. Generalised estimating equations (GEE) with 6, 12, 18 and 24 months time lags were used to determine whether high exposure was related to symptoms at follow-up. The results showed that high scores on 9 out of 13 scales, including previous symptoms, were significantly related to arm, shoulder and neck symptoms at follow-up. These results provide support for the predictive validity of the RSI QuickScan questionnaire.

Practitioner Summary: The results showed that high scores on 9 out of 13 scales, including previous symptoms, were significantly related to arm, shoulder and neck symptoms at follow-up. The RSI QuickScan questionnaire may be recommended as a tool in the identification of computer workers who should be targeted with interventions aimed at prevention of future symptoms.     

Validity of the Acti4 software using ActiGraph GT3X+accelerometer for recording of arm and upper body inclination in simulated work tasks

The validity of inclinometer measurements by ActiGraph GT3X+ (AG) accelerometer, when analysed with the Acti4 customised software, was examined by comparison of inclinometer measurements with a reference system (TrakStar) in a protocol with standardised arm movements and simulated working tasks. The sensors were placed at the upper arm (distal to the deltoid insertion) and at the spine (level of T1-T2) on eight participants. Root mean square errors (RMSEs) values of inclination between the two systems were low for the slow- and medium-speed standardised arm movements and in simulated working tasks. Fast arm movements caused the inclination estimated by the AG to deviate from the reference measurements (RMSE values up to ～10°). Furthermore, it was found that AG positioned at the upper arm provided inclination data without bias compared to the reference system. These findings indicate that the AG provides valid estimates of arm and upper body inclination in working participants.     

Combined exposures of whole-body vibration and awkward posture: a cross sectional investigation among occupational drivers by means of simultaneous field measurements

Abstract

Objective: Multifactorial workloads such as whole-body vibration (WBV), awkward posture and heavy lifting are potential predictors for low back pain (LBP). In this study, we investigate the association between LBP and these exposures among 102 professional drivers. Methods: The combined exposures of WBV and posture are measured at different workplaces. Health and personal data as well as information about lifting tasks are collected by a questionnaire. Results: The daily vibration exposure value (odds ratio 1.69) and an index for awkward posture (odds ratio 1.63) show significant association with the occurence of LBP. Awkward posture and heavy lifting appear to be more strongly associated with sick leave than WBV exposure. Furthermore, a combination of the measurement results of WBV and awkward posture into one quantity also shows significant correlation to LBP. Conclusion: The combined exposure of WBV and awkward posture can be described in terms of the daily vibration exposure and the index for awkward posture. This facilitates work place assessments and future research in this area.

Practitioner Summary: For the first time, quantitative measures combining whole-body vibration and awkward posture exposures have shown to correlate with the occurrence of low back pain significantly. This validates the proposed quantities and measurement methods, which facilitate workplace assessments and assist in the design of further studies which are necessary to establish a causal exposure–response relationship.     

Neck pain combined with arm pain among professional drivers of forest machines and the association with whole-body vibration exposure

The purpose of this study was to investigate the existence of neck pain and arm pain among professional forest machine drivers and to find out if pain were related to their whole-body vibration (WBV) exposure. A self-administered questionnaire was sent to 529 forest machine drivers in northern Sweden and the response was 63%. Two pain groups were formed; 1) neck pain; 2) neck pain combined with arm pain. From WBV exposure data (recent measurements made according to ISO 2631–1, available information from reports) and from the self-administered questionnaire, 14 various WBV exposure/dose measures were calculated for each driver. The prevalence of neck pain reported both for the previous 12 months and for the previous 7 d was 34% and more than half of them reported neck pain combined with pain in one or both arms. Analysis showed no significant association between neck pain and high WBV exposure; however, cases with neck pain more often experienced shocks and jolts in the vehicle as uncomfortable. There was no significant association between the 14 WBV measures and type of neck pain (neck pain vs. neck pain combined with arm pain). It seems as if characteristics of WBV exposure can explain neither existence nor the type of neck pain amongst professional drivers of forest machines. The logging industry is important for several industrialised countries. Drivers of forest machines frequently report neuromusculoskeletal pain from the neck. The type of neck pain is important for the decision of treatment modality and may be associated with exposure characteristics at work.     

The impact of ergonomics intervention on psychosocial factors and musculoskeletal symptoms among office workers

Musculoskeletal disorders have a multi factorial etiology that includes not only physical risk factors but also psychosocial factors. This study aimed to investigate psychosocial risk factors and musculoskeletal symptoms among office workers of an Iranian oil refinery and also to examine the subsequent effects of ergonomics intervention on musculoskeletal discomfort and psychosocial risk factors.In this study, 73 office workers as a case group and 61 office workers as a control group from an Iranian oil refinery plant were randomly selected and examined. The Nordic Musculoskeletal Disorders Questionnaire and the Persian version of the Job Content Questionnaire (P-JCQ) were used as collecting data tools before and after the interventional program.Low back problem (28.8%) was found to be the most common problem among the office workers. Significant differences found between prevalence rates of reported musculoskeletal in upper back, lower back and feet/ankle regions before and after intervention. Our findings showed that psychosocial variables were not affected by the intervention. The only variables on the P-JCQ that were significantly different pre/post intervention are the physical variables: physical job demands, physical exertion and physical isometric load. None of the other psychosocial variables were found to be significant. With the top management support, improvements in all office workstation components were made successfully.

Relevance to industry

Recently, changes in the nature of work draw increased attention to the relation between psychosocial factors and musculoskeletal disorders. The results of the current study indicate that a well conducted implementation of an interventional program can lead to a decrease in musculoskeletal symptoms and to some extent in the psychosocial factors at work.     

A four-year follow-up study of physical working conditions and perceived mental and physical strain among food industry workers

This study hypothesized that in a longitudinal setting deteriorating physical working conditions increases the perceived physical and mental strain among food processing employees. The study was conducted in 2003 and 2007. It examined 248 blue-collar workers, all of whom were in the same occupation throughout the entire follow-up period. The data were obtained through a structural questionnaire distributed to the employees at the workplace. Mental strain had increased (7%) significantly among younger employees during the follow-up. The changes in mental strain for the younger employees were positively associated with the changes in physical strain. The changes in physical strain were also significantly associated with the changes in physical working conditions among both younger and the older workers. The results of this study partly support the study hypothesis, namely that deteriorating physical working condition increases physical strain and also increases mental strain, especially among younger employees.     

Integrating a hip belt with body armour reduces the magnitude and changes the location of shoulder pressure and perceived discomfort in soldiers*

Soldiers carry heavy loads that may cause general discomfort, shoulder pain and injury. This study assessed if new body armour designs that incorporated a hip belt reduced shoulder pressures and improved comfort. Twenty-one Australian soldiers completed treadmill walking trials wearing six different body armours with two different loads (15 and 30 kg). Contact pressures applied to the shoulders were measured using pressure pads, and qualitative assessment of comfort and usability were acquired from questionnaires administered after walking trials. Walking with hip belt compared to no hip belt armour resulted in decreased mean and maximum shoulder pressures (p < 0.005), and 30% fewer participants experiencing shoulder discomfort (p < 0.005) in best designs, although hip discomfort did increase. Laterally concentrated shoulder pressures were associated with 1.34-times greater likelihood of discomfort (p = 0.026). Results indicate body armour and backpack designs should integrate a hip belt and distribute load closer to shoulder midline to reduce load carriage discomfort and, potentially, injury risk.

Practitioner Summary: Soldiers carry heavy loads that increase their risk of discomfort and injury. New body armour designs are thought to ease this burden by transferring the load to the hips. This study demonstrated that designs incorporating a hip belt reduced shoulder pressure and shoulder discomfort compared to the current armour design.     

Incidence of self-reported reduced productivity owing to musculoskeletal symptoms: association with workplace and individual factors among computer users

The aim of the present study was to assess the incidence and identify possible risk factors for self-reported reduced productivity owing to musculoskeletal symptoms among computer users. DESIGN: a cohort study with a baseline questionnaire and monthly follow ups during 10 months. METHODS: the study base consisted of 1,283 computer users, 636 men and 896 women. Ergonomists observed workstation characteristics before entering the cohort. Cases were defined as subjects reporting reduced productivity or reporting being on sick leave owing to musculoskeletal symptoms. RESULTS: women had approximately two times the incidence of self-reported reduced productivity owing to symptoms in the neck, shoulder and in the forearm/hand than men. There was no difference in gender for the incidence of self-reported reduced productivity owing to back symptoms. Working overtime and job demands were risk factors for self-reported reduced productivity owing to neck and back symptoms. Physical exercise fewer than 8 times the last month was a risk factor for self-reported reduced productivity owing to neck, shoulder and forearm/hand symptoms. Computer mouse use for more than 0.5 h/day was a risk factor for self-reported reduced productivity owing to shoulder and forearm/hand symptoms. CONCLUSIONS: risk factors for self-reported reduced productivity owing to musculoskeletal symptoms included life style factors, such as overweight and low physical exercise, occupational factors, such as overtime, job demands and computer mouse operating time.     

Comparison of posture and muscle control pattern between male and female computer users with musculoskeletal symptoms

The primary purpose of this study was to compare the posture and muscle control patterns between male and female computer users with musculoskeletal symptoms. Forty computer users were recruited. Each subject performed a preferred speed typing, a fast speed typing, and a repetitive mouse task. The independent variables were gender, typing speed, and time. There were significant differences between genders for head and neck flexion angles when they were performing the preferred speed typing task. Significant differences between genders were also found for upper extremity angles when they were performing the repetitive mouse task. Male computer users had a smaller root mean square of the right extensor digitorium than females. In general, postural differences were significant between genders, even when the subjects' table and chair were adjusted to meet their anthropometry. Our results suggest that modifications of the computer working environment may be different between genders.     

A case study of Taiwanese custom-beverage workers for their musculoskeletal disorders symptoms and wrist movements during shaking task

This study administered the Nordic Musculoskeletal Questionnaire to a convenience sample of 106 workers at custom-beverage vendors in Taiwan (who prepare drinks through manual shaking) to explore their work-related musculoskeletal disorders (WMSDs) and identify risk factors for these disorders symptoms. Wrist posture for twenty workers were also measured for three shaking methods using an electrogoniometer. The prevalence of musculoskeletal discomfort in the past year among the respondents was 88.6%. Most of them reported discomfort in their hands/wrists (67.9%), followed by the lower back/waist (44.3%), knees (39.6%), and shoulders (38.7%). Hands/wrists and low back/waist discomforts varied significantly by the worker's gender and the number of working days per week, and hands/wrists discomfort also by the shaking method. Knee discomfort was affected by age and whether rest periods at work were scheduled, whereas shoulder discomfort by work experience, number of working days per week, and number of drink orders prepared per day. Measurements in wrist postures exhibited that repetitive activity for each wrist was as high as 4 time/s for a cup preparation (10 s). Among shaking methods, curve swing can constrain the shakers' wrists in a relatively neutral position and a smaller range of movement than others, regardless of the sex.Relevance to industryBecause of the nature of shaking-based beverage preparation work, the respondents have a higher prevalence of discomfort in the hands/wrists, lower back/waist, knees, and legs/ankles than their counterparts in other industries. These findings are expected to inform the prevention and alleviation of musculoskeletal discomfort in custom-beverage workers.     

The investigation of work-related musculoskeletal disorders among female workers in a hazelnut factory: Prevalence,working posture,work-related and psychosocial factors

BackgroundWork-related musculoskeletal disorders (WMSDs) are the most common occupational health problems in the industrialized world. The identification of WMSDs specific to occupation is essential to plan and implement preventative programs. This study investigated the prevalence of WMSDs and determined the factors related to the severity of the most common disorders among female workers in a hazelnut factory.MethodsA total of 114 female workers were examined in this cross-sectional study using the Nordic Musculoskeletal Questionnaire, the Dutch Musculoskeletal Questionnaire, and an author-developed questionnaire (for socio-demographic characteristics and psychosocial factors). Working posture, craniovertebral angle, thoracic kyphosis angle (TKA), and lumbar lordosis angle were evaluated based on a photogrammetry method using the ImageJ program.ResultsThe prevalence of WMSDs in at least one body part during the last 12 months was 92.1%. The highest prevalence of WMSDs was in the lower back (61.4%), neck (57.9%), shoulder (53.6%), and upper back (45.6%). The least affected part was the elbow. Lower back, shoulder, and neck disorders were the most common causes of activity limitation. The severity of lower back pain was associated with stress in the workplace and work-related factors. The neck pain severity was related to craniovertebral angle and work-related factors. The shoulder pain severity increased with TKA and employment duration. TKA was related to upper back pain severity.ConclusionsWMSDs are common among female workers in a hazelnut factory. Reorganizing of working posture, work-related factors, and stress at work may be beneficial to decrease the prevalence of WMSDs and pain severity.Relevance to Industry; The female workers in the hazelnut factory are vulnerable to the work-related musculoskeletal disorders, particularly in the spinal region. The employers should endeavor to improve the health of the workers by the adjustment of the working posture and environmental factors.