Work posture,working conditions and musculoskeletal outcomes in agricultural workers

This study evaluated the working postures, working conditions and musculoskeletal outcomes among different agricultural workers in Iran. Data were collected using questionnaires and direct observations of posture (using the Rapid Upper Limb Assessment [RULA] method) from 377 farmers including 150 rice farmers, 122 vegetable growers, and 105 greenhouse workers. The overall prevalence of musculoskeletal symptoms, particularly in the low back (75.1%), knees (62.1%), upper back (61.55%), and neck (59.9%) was very high, and 72.6% of farmers experienced more than three locations of pain/discomfort. The mean RULA grand score of 6.7 highlighted that most farmers needed immediate investigation and changes in their working postures. Being female (neck pain), occupation (rice farmers – low back pain), number of years worked as an agricultural worker (neck and knee pain), prolonged daily working hours (upper back pain), job satisfaction (neck and low back pain), fast working (upper back pain), and working postures (neck, upper back, low back and knee pain) were independently associated with the presence of musculoskeletal symptoms. These findings emphasise the need for multiple component interventions to improve the working conditions of this population.     

Rail system decreases physical strain in milking

The physical strain of milking can be reduced by improving work methods. The aim of this study was to investigate the influence of the rail system (Alfa Line) on the physical strain and work time in tie stall milking. The measurements were performed before the installation of the rail system and after the one year of using the system. The subjects were two male and three female farmers (age 42 ± 2.1 years, mean ± SD), working daily in their barns. The mean heart rate (HR) and heart rate range (HRR) of the four subjects was lower when milking with the rail system. The simultaneous bent and twisted back postures decreased from 29.1% to 10.6% (p < 0.05). Postures with the arms held above shoulder level were reduced to about a half. The proportion of standing with both legs straingt increased and squatting postures diminshed in milking with the rail system. The mean milking time per cow was 3.8 min with the traditional machine milking method and 2.9 min with the rail method. This technical equipment reduced especially the musculoskeletal load in tie stall milking.     

Postural, epidemiological and biomechanical analysis of luggage handling in an aircraft luggage compartment

Loading and unloading of luggage in an aircraft luggage compartment is carried out manually in uncomfortable working position. In this study, the loading work was analysed by surveying musculoskeletal symptoms, by recording the working postures and techniques at work, and by simulating the loading work in a mock-up of a DC-9 aircraft compartment. Low back, knees and shoulders were exposed to mechanical load in luggage handling. Video recordings were used to analyse posture and work technique. In the simulated luggage compartment in the laboratory, ground reaction forces, intra-abdominal pressure (IAP) and electromyography (EMG) signals from back and shoulder muscles were recorded simultaneously. Loading in sitting, squatting and kneeling were the postures that were used the most often. Unloading was generally less stressful than loading, involving less static work. Handling time was shortest when kneeling but knee symptoms were dominant. Lateral ground reaction forces and EMG activity from trapezius were highest when sitting, and IAP peaks were greatest when squatting. Thus each posture had major, though differing, disadvantages and a radical redesign of the DC-9 luggage compartment was clearly indicated.     

Work activities and musculoskeletal complaints among preschool workers

The potential for musculoskeletal trauma among preschool workers has been largely unexplored in the United States. This case report describes an investigation conducted to identify and evaluate possible causes of back and lower extremity pain among 22 workers at a Montessori day care facility. Investigators met with and distributed a questionnaire to school employees, and made measurements of workstation and furniture dimensions. Investigators also recorded the normal work activities of school employees on videotape, and performed a work sampling study to estimate the percentage of time employees spend performing various tasks and in certain postures.

Questionnaire results from 18 employees indicated that back pain/discomfort was a common musculoskeletal complaint, reported by 61% of respondents. Neck/shoulder pain, lower extremity pain and hand/wrist pain were reported by 33, 33 and 11% of respondents, respectively. Observation and analysis of work activities indicated that employees spend significant periods of time kneeling, sitting on the floor, squatting, or bending at the waist. Furthermore, staff members who work with smaller children (i.e. six weeks to 18 months of age) performed more lifts and assumed more awkward lower extremity postures than employees who work with older children (3–4 years of age). Analysis of two lifting tasks using the revised NIOSH lifting equation indicated that employees who handle small children may be at increased risk of lifting-related low back pain. Investigators concluded that day care employees at this facility are at increased risk of low back pain and lower extremity (i.e. knee) injury due to work activities that require awkward or heavy lifts, and static working postures. Recommendations for reducing or eliminating these risks by modifying the workplace and changing the organization and methods of work are presented.     

The impact of ergonomic intervention on individual health and corporate prosperity in a telecommunications environment

This paper is a summary of several papers published in different journals and conference proceedings. The contents deal with the incidence of load related musculoskeletal illness of female workers exposed to various workloads. Furthermore, the changes in workload due to improved workplace design and the effect on the incidence of musculoskeletal illness was evaluated. The sick-leave due to musculoskeletal illness was reduced from 5·3% to 3·1% and the reduction in turn-over from 30·1% to 7·6%. The cost and the benefits of this ergonomic intervention were analysed, and showed that an investment of NOK. 350 000 produced total savings of NOK. 3 200 000.

Postural load was assessed by recording electromyography (EMG) on the upper part of musculus trapezius, postural angles of the upper arm and flexion/extension of the head and back. A quantitative relationship was found between the static trapezius load and the development of musculoskeletal sick-leave, related to the length of employment. Indications were found that certain factors were associated with reduced incidence of musculoskeletal illness. These were:

? increasing the number and total duration of trapezius load below 1% to 2% MVC (Maximum Voluntary Contraction);

? reducing the magnitude of flexion angle of the upper arm in the sagittal plane and distributing the work between flexors and extensors; and

? a more dynamic work pattern of the upper arm.

The relationship between postural load and musculoskeletal injury was studied in comparable groups of female workers with respect to age, working hours per day and time of employment. Psychosocial problems, spare time activities and living habits of the workers did not show any significant differences across the groups. The results from this study indicate that:

? the static trapezius load must be kept at a minimum;

? a median arm flexion should be less than 15° and a median arm abduction less than 10°. These values seem roughly to approach an acceptable arm position; and

? a forward median flexion of the back of less than 20° seems not to lead to a higher rate of low back pain for workers with long periods of employment.     

Observations of working postures in garages using the Ovako Working posture Analysing System (OWAS) and consequent workload reduction recommendations

The working postures of mechanics (n = 84) in 42 garages were observed using the Ovako Working posture Analysis System (OWAS). During observation, both working postures and work activities were recorded. A computer program was developed for the data analyses. Using this program it is possible to calculate the working posture load for each work activity and the contribution of a specific activity to the total working posture load. This is a substantial extension of the original OWAS method. Five out of 19 observed postures of the body members were classified as Action Category 2, which suggests they were slightly harmful to the musculoskeletal system and likely to cause discomfort. Of the so-called typical working postures, 31.9% was classified in Action Category 2, suggesting that during a substantial part of the working day typical working postures occur which are at least slightly harmful to the musculoskeletal system. Moreover, those work activities principally causing the workload to fall in OWAS' higher Action Categories were identified. For each of these three work activities an alternative work method was observed. The data show that in all three work activities the use of a vehicle lift reduces the number of poor working postures thereby reducing the load on the musculoskeletal system.     

Workers' education

Health education is one of the most popular weapons against low back pain and other work-related musculoskeletal disorders.

It is used for both primary and secondary prevention to teach healthy life and work habits and to improve body mechanics in order to promote and maintain health. It is assumed that with a few hours of teaching, people adopt new working postures and movements, make ergonomic changes in their environment, and start exercising.

The most common teaching method is lecturing, with visual aids. The practical session is often short.

In evaluations shortly after the sessions, participants have been satisfied, their knowledge has increased, and in some cases the number of injuries or sick leaves has decreased. Follow-ups have shown that the health situation has returned to its former state within two years. In health education, aimed at preventing musculoskeletal injuries, the principle should be ‘learning by doing’. Instead of lecturing, the programmes should have a comprehensive approach, which includes the improvement of the live situation and environment, and involves the entire community.

Three programmes (the prevention of data entry operators' neck and upper limb disorders, early rehabilitation courses for forest workers, and workers guidelines to self-help) are presented and the teaching methods and contents analysed with special interests in the didactic methods and in participation of workers.     

Quantitative postural load assessment for whole body manual tasks based on perceived discomfort

Many Korean workers are exposed to repetitive manual tasks or prolonged poor working postures that are closely related to back pain or symptoms of musculoskeletal disorders. Workers engage in tasks that require not only handling of heavy materials, but also assuming prolonged or repetitive non-neutral work postures. Poor work postures that have been frequently observed in the workplaces of shipbuilding shops, manufacturing plants, automobile assembly lines and farms often require prolonged squatting, repetitive arm raising and wrist flexion and simultaneous trunk flexion and lateral bending. In most manufacturing industries, workers have to assume improper work postures repetitively, several hundreds of times per day depending on daily production rate. A series of psychophysical laboratory experiments were conducted to evaluate the postural load at various joints. A postural load assessment system was then developed based on a macro-postural classification scheme. The classification scheme was constructed based on perceived discomfort for various joint motions as well as previous research outcomes. On the basis of the perceived discomfort, postural stress levels for the postures at individual joints were also defined by a ratio scale to the standing neutral posture. Laboratory experiments simulating automobile assembly tasks were carried out to investigate the relationship between body-joint and whole-body discomfort. Results showed a linear relationship between the two types of discomfort, with the shoulder and low back postures being the dominant factor in determining the whole body postural stresses. The proposed method was implemented into a computer software program in order to automate the procedure of analysing postural load and to enhance usability and practical applicability.     

Quantitative postural load assessment for whole body manual tasks based on perceived discomfort

Many Korean workers are exposed to repetitive manual tasks or prolonged poor working postures that are closely related to back pain or symptoms of musculoskeletal disorders. Workers engage in tasks that require not only handling of heavy materials, but also assuming prolonged or repetitive non-neutral work postures. Poor work postures that have been frequently observed in the workplaces of shipbuilding shops, manufacturing plants, automobile assembly lines and farms often require prolonged squatting, repetitive arm raising and wrist flexion and simultaneous trunk flexion and lateral bending. In most manufacturing industries, workers have to assume improper work postures repetitively, several hundreds of times per day depending on daily production rate. A series of psychophysical laboratory experiments were conducted to evaluate the postural load at various joints. A postural load assessment system was then developed based on a macro-postural classification scheme. The classification scheme was constructed based on perceived discomfort for various joint motions as well as previous research outcomes. On the basis of the perceived discomfort, postural stress levels for the postures at individual joints were also defined by a ratio scale to the standing neutral posture. Laboratory experiments simulating automobile assembly tasks were carried out to investigate the relationship between body-joint and whole-body discomfort. Results showed a linear relationship between the two types of discomfort, with the shoulder and low back postures being the dominant factor in determining the whole body postural stresses. The proposed method was implemented into a computer software program in order to automate the procedure of analysing postural load and to enhance usability and practical applicability.     

Standing, sitting and associated working conditions in the Quebec population in 1998

Working posture is an important determinant of musculoskeletal and vascular health. Knowledge of the context and type of postures is necessary in order to examine their associations with health-related outcomes. This study describes self-reported usual working postures in a population and their associations with other working conditions and demographic variables. The 1998 Quebec Health and Social Survey is a population-based survey of 11,986 private households in the province of Quebec. It contained a self-administered questionnaire, including an extensive occupational health section. The analyses in this study were limited to respondents with paid employment who had at least 6 months seniority in their current job, comprising 9,425 subjects. The overall prevalence of usual work in a standing posture is 58%; it is more common among men, workers under 25 years, those in the two lowest educational quintiles and those with incomes under 20,000 Canadian dollars. Only one person in six who works standing reports being able to sit at will. Women and men differ in the types of usual standing and sitting postures at work. Those who work standing and/or who work in more constrained postures are more likely to be exposed to other physical work demands, such as handling heavy loads, repetitive work, forceful exertion and low job decision latitude. The association between decision latitude and constrained postures is an important link between psychosocial and physical stressors in the workplace. In epidemiological studies, exposure covariation and interactions should be considered in the generation and interpretation of the associations between work postures and musculoskeletal disorders.     

Load moments and myoelectric activity when the cervical spine is held in full flexion and extension

Abstract

Sustained joint load in extreme positions (namely maximally flexed or extended positions) has been described as causing pain. The aim of the present study is to analyse eight different sitting work postures with respect to extreme positions, and to assess the mechanical load and the levels of muscular activity arising in defined extreme positions of the cervical spine. Ten healthy female workers from an electronics plant took part in laboratory experiments. For seven of these, levels of neck and shoulder muscular activity in sitting postures with the cervical spine in different manually-adjusted extreme positions were recorded using surface electrodes. Loading moments of force about the bilateral motion axis of the atlanto-occipital joint (Occ-C1) and the spinal cervico-thoractc motion segments (C7-T1) were calculated. Extreme or almost extreme positions occurred in sitting postures with the thoracolumbar back inclined slightly backwards or with the whole spine flexed. Electromyographic (EMG) activity levels were very low in the manually-adjusted extreme positions. The load moment for the Occ-Cl joint when the whole neck was flexed was only 1·2 times the value for the neutral position of the head, but for C7-T1 it increased to 3·6 times. It is concluded that extreme positions of the cervical spine do occur in sitting work postures, and that the levels of muscular activity in such positions are low. Thus, recordings of muscle activity and calculations of load moment alone are not a sufficient basis for evaluating work postures: thorough recordings of spine positions should be included.     

Physical workload and psychosocial working conditions in Swedish pig transport drivers

Working conditions of 20 Swedish pig transport drivers (PTD) were assessed by a questionnaire, a workshop, and recorded postures and movements during on-farm loading, driving, unloading at abattoir and vehicle cleaning. High arm positions and high frequencies of shoulder problems indicated an excessive physical load on shoulders. Extreme crouching postures inside vehicles and high frequencies of lower back problems indicated high load on the back of PTDs. Inadequate design of on-farm loading areas was associated with knee discomfort. Observed variation in workload between PTDs could be explained by differences in physical working environment and pig handling practices. PTDs reported high job satisfaction and commitment although conflicts with farmers and official veterinarians, as well as regulatory conflicts were emphasized. We conclude that issues of inadequate farm and abattoir facilities, stakeholder conflicts and insufficient training in animal handling need to be addressed to ensure sustainable PTD working conditions.     

Investigation of musculoskeletal symptoms and ergonomic risk factors among female sewing machine operators in Turkey

This cross-sectional study aimed to identify the prevalence of musculoskeletal symptoms and ergonomic risks in female sewing machine operators at a textile company. The study sample comprised all female sewing machine operators in the company. The sample included 283 sewing machine operators. Data were collected through the use of the adapted Nordic Musculoskeletal Questionnaire and by direct observations via the rapid upper limb assessment (RULA) to determine ergonomic risks. RULA is a validated tool for assessment of ergonomic risks. The mean age of the women was 30.2 (SD: 8.4) and the mean number of years of employment was 13.4 (SD: 5.5). The highest prevalence rates for the women’s musculoskeletal symptoms were in the trunk (62.5%), neck (50.5%), and shoulder (50.2%). Of the women, 65% had experienced musculoskeletal pain or discomfort over the last 6 months. Pain intensity of these symptoms was assessed with a visual analogue scale. The average pain intensity of the women was found to be 3.5 (SD: 2.8). Results of the RULA scores were found to be quite high. There were no employees who received RULA scores of 1–2, which indicates acceptable postures (all scores >5). The final RULA scores of 6.9 indicate that the participants’ postures at their work stations need to be investigated immediately.

Relevance to industry

This study based on the RULA method allowed to perform a rapid and quite correct evaluation tolls for SMOs. For this research population, the research findings provided fundamental data on the prevalence of musculoskeletal symptoms and ergonomic risks among Turkish female SMOs.     

Classroom posture and self-reported back and neck pain in schoolchildren

The study reported here aims to identify the extent of back pain experienced by 11-14 year old schoolchildren, and establish the intensity, duration and frequency of exposure to physical risk factors present in schools. This paper considers the sitting postures of schoolchildren in the classroom. The sitting postures of 66 children were recorded in normal lessons using the Portable Ergonomic Observation Method (PEO). The study found significant associations between flexed postures and low back pain. Static postures and neck and upper back pain were also associated. This study has implications for schools, designers and people in the field of work related musculoskeletal disorders. Further research is required to examine the association between sitting posture and pain reported at different spinal locations.     

Physical demands of work and health complaints among women working late in pregnancy

Health complaints before, during and after pregnancy were collected from 2251 women in Montreal who had been in paid employment beyond the twenty-seventh week of their first or second pregnancy. Complaints of breathlessness, fatigue, back pain, varicose veins and haemorrhoids increased during pregnancy, the proportion of women reporting these symptoms being greatest in the third trimester. Complaints at this stage were found to be systematically related to job postures and other physical work demands, prolonged periods of standing, particularly with the back bent forward, twisting the trunk and lifting weights all being found troublesome by workers late in their pregnancy. Three months after delivery the level of health complaints had generally returned to that before pregnancy. This was so for all symptoms except varicose veins and haemorrhoids. No relation was found between trouble with haemorroids and the physical demands of work in pregnancy. Problems with varicose veins three months after delivery were however, more frequent than expected in those whose job had required them to stand during pregnancy for more than 2h at a stretch. There was also some indication that women in physically demanding jobs took longer to recover from their confinement.     

The prevalence of self-reported musculoskeletal symptoms among loggers in Poland

This paper presents an analysis of the occurrence of self-reported musculoskeletal symptoms (MSD) among loggers in Poland. As a diagnostic tool, a modified Nordic questionnaire was used. The questionnaire was completed by 353 professional loggers. The results showed the dominant MSD symptoms during the last twelve months to be those of the lower back (66.3%) and hands/wrists (left 50.1%, right 51.3%). A significant percentage of respondents also reported symptoms of the upper back (45.6%), shoulders (38.2% for each shoulder), and knees (left 36.0%, right 39.4%). Statistically significant relationships were found between the age of the subjects, the work experience, and the number of body regions in which MSD symptoms were reported during the last twelve months. These results show that education and recommendations to use safe working postures, techniques and organization of work with a chainsaw should still be improved.Relevance to industryThis paper analyzes the prevalence of MSD symptoms among Polish loggers and provides a basis for the implementation of preventative measures.     

Posture analysis among Flemish secondary school teachers: difference between the use of chalkboards and electronic school boards during classroom teaching

The aim of this study was to (i) make a posture analysis of teachers during theoretical classroom teaching; (ii) to estimate the risk for the development of musculoskeletal problems (MSP); (iii) test the hypotheses that an electronic school board (EB) has more ergonomic advantages for teachers. Thirty-five secondary school teachers, of which 15 used an EB and 20 used chalkboards, were selected by convenience sampling and filmed during 30 min of a theoretical course. Posture analysis of back, arms, legs and risk assessment was performed using the Ovako Working Posture Analysis System. Most of the teachers’ postures did not indicate a higher risk for MSP. However, some postures may be harmful when accumulated for several hours of teaching a day; especially, long periods of standing and standing with a bended back. Results also indicated that currently the use of an EB does not improve teachers’ posture.

Practitioner Summary: The relationship between objectively measured physical work load and risk for injuries among teachers was not analysed so far. In this study teachers’ posture was analysed using the OWAS method. Prolonged standing and forward bending were identified as risk postures. Also, using an electronic school board currently does not improve posture.     

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 prevalence of musculoskeletal symptoms among British Columbia sonographers

A survey (n = 211, 92% response rate) was carried out to determine baseline prevalence of musculoskeletal symptoms and identify related biomechanical, psychosocial, work organization and demographic factors among the population of sonographers in British Columbia, Canada. Ninety-one percent of respondents reported musculoskeletal pain or discomfort that they associated with the work tasks of scanning. Almost half reported frequent and severe symptoms. The neck, shoulder, and upper back were the main symptomatic body sites. A very small minority were absent from work due to the symptoms, with more than two thirds of respondents reporting working in pain. Bivariate analyses found significant associations between scanning time, static postures, psychosocial factors, and degree of musculoskeletal symptoms.