Further studies of shoulder and neck pain and exposures in customer service work with low biomechanical demands

The aim of the study was to establish insight into work exposures that cause shoulder and neck pain among occupational groups that have low biomechanical exposure and experience work stress from client/customer contact, among other exposures. Four occupational groups were studied, in health care (n = 20), retail (n = 22), banking (n = 26), and university secretaries (n = 26), a total of 94 volunteers. Thirty-nine were classified as pain-afflicted in the shoulder and neck, while 55 were pain-free. The subjects' perceptions of biomechanical and psychosocial exposures were established by use of quantitative questionnaires and by explorative interviews with open-ended questions, covering the same themes. Heart rate and trapezius EMG were recorded over a full workday and the following leisure period. Trapezius median and static activity during work were 3.3% and 0.3% EMG(max), only marginally higher than trapezius activity in the leisure period (2.7% and 0.2% EMG(max)). The quantitative questionnaire did not identify any variable that correlated with shoulder and neck pain except perceived general tension. The interviews established that the interaction with clients or customers was an important source of work stress. Such stress appeared to be a complex entity not easily characterized by established psychosocial questionnaires. The physiological variables were at most weakly elevated in periods with high stress as compared to periods with low stress. The authors caution against relying on standardized quantitative questionnaires and/or physiological recordings to characterize work stress in occupations with emotional stress through client/customer service work.     

Trapezius muscle activity as a risk indicator for shoulder and neck pain in female service workers with low biomechanical exposure

Electromyographic activity of the upper trapezius muscles was recorded over the workday for two groups of service workers, shopping centre (n = 22) and healthcare workers (n = 44), both with low observed biomechanical exposure. Static and median EMG activity level, number of EMG gaps and gap time were determined. The variability of these variables over the workday was examined by calculating the coefficient of variation (CV) and the intraclass correlation coefficient (ICC) of 1-h consecutive recording periods. All variables except gap time showed acceptable reliability (ICC = 0.69-0.78), i.e. the largest fraction of variance in the data set was due to intersubject variance, despite relatively large hour-to-hour variation (CV = 0.21-0.62). The EMG activity level in the trapezius muscles was low (static activity level < 1% EMG_max), despite the high prevalence of shoulder and neck pain for both groups of workers. In addition to the work recordings, tests were performed to determine intersubject variation in muscle activity when adopting a standardized resting posture, and in a dynamic muscle activity pattern during paced arm movement. Neither the EMG variables from the work recordings nor the tests with EMG recording indicated higher trapezius EMG activity levels for workers with pain in the shoulders and neck in this study. The low EMG levels are interpreted to indicate a low risk of developing shoulder and neck complaints due to biomechanical exposure for both groups of workers. The possibility of pain-initiating mechanisms, associated with stress and not mediated through muscle activity, is considered in the discussion.     

Shoulder and neck complaints in customer relations: individual risk factors and perceived exposures at work

Perceived psychosocial and biomechanical exposures, individual factors and pain in the shoulder and neck were recorded in two groups of female service workers (healthcare and shopping centre workers). The jobs investigated were characterized by ‘much’ direct human relations, ‘little’ sitting and ‘much’ standing, and were light work by physiological or biomechanical criteria but potentially psychosocially demanding. A screening survey (n = 400 females) was the basis for the selected sample (n = 66 females), which was the object of the main investigation of this study. Reliability of the questionnaires was tested in a separate group of female healthcare workers (n = 29). Heart rate recordings through the work day estimated workload. There was a high prevalence of shoulder and neck pain (>50%) for both work groups. In the two populations it proved difficult to explain shoulder and neck pain by reported physical and psychosocial exposures or individual factors, except by the variable ‘perceived general tension’, which clearly differentiated workers with and without pain. The findings in this study indicated, first, that perceived general tension might be an independent risk factor for muscle pain and, second, that this might be related to personality factors. However, this putative relationship must be verified in a longitudinal study. As no variable describing exposures in the working environment was associated with shoulder and neck pain, the question is posed whether such complaints can be considered work-related. Alternatively, the variables used to describe mechanical and psychosocial exposures in this study may have low specificity in characterizing work-related risk factors for service workers with customer relations.     

Shoulder and neck complaints in customer relations: individual risk factors and perceived exposures at work

Perceived psychosocial and biomechanical exposures, individual factors and pain in the shoulder and neck were recorded in two groups of female service workers (healthcare and shopping centre workers). The jobs investigated were characterized by 'much' direct human relations, 'little' sitting and 'much' standing, and were light work by physiological or biomechanical criteria but potentially psychosocially demanding. A screening survey (n = 400 females) was the basis for the selected sample (n = 66 females), which was the object of the main investigation of this study. Reliability of the questionnaires was tested in a separate group of female healthcare workers (n = 29). Heart rate recordings through the work day estimated workload. There was a high prevalence of shoulder and neck pain (> 50%) for both work groups. In the two populations it proved difficult to explain shoulder and neck pain by reported physical and psychosocial exposures or individual factors, except by the variable 'perceived general tension', which clearly differentiated workers with and without pain. The findings in this study indicated, first, that perceived general tension might be an independent risk factor for muscle pain and, second, that this might be related to personality factors. However, this putative relationship must be verified in a longitudinal study. As no variable describing exposures in the working environment was associated with shoulder and neck pain, the question is posed whether such complaints can be considered work-related. Alternatively, the variables used to describe mechanical and psychosocial exposures in this study may have low specificity in characterizing work-related risk factors for service workers with customer relations.     

Electromyographic fatigue in neck/shoulder muscles and endurance in women with repetitive work

EMG was recorded with surface electrodes from the trapezius and deltoid muscles during a static endurance test at approximately 20% of maximal voluntary contraction. Objective parameters for localized muscular fatigue were derived from the time course of the root mean square (RMS) and mean power frequency (MPF) of the EMG recordings. Isotonic regression is introduced as a tool for assessment of such parameters. The most pronounced sign of fatigue for trapezius was an increase in the RMS values, while for deltoid it was a decrease in the MPF values. This could be explained by the different functions of the two muscles. The endurance time for a group of 11 women in industrial work with repetitive short-cycled work tasks who were diagnosed with neck/shoulder disorders (tension neck) was significantly shorter (p<0·05) than for a group with the same work, but without neck/shoulder disorders (n=ll), and shorter than for a control group (n=ll). Regarding the EMG fatigue measures, there were no significant differences between the three groups. We did not find any relationships between endurance time and the EMG parameters. The results indicate that neck/shoulder disorders were not associated with divergent mechanisms for developing fatigue in the muscles, as recorded with surface EMG.     

Trapezius muscle activity as a risk indicator for shoulder and neck pain in female service workers with low biomechanical exposure

Electromyographic activity of the upper trapezius muscles was recorded over the workday for two groups of service workers, shopping centre (n = 22) and healthcare workers (n = 44), both with low observed biomechanical exposure. Static and median EMG activity level, number of EMG gaps and gap time were determined. The variability of these variables over the workday was examined by calculating the coefficient of variation (CV) and the intraclass correlation coefficient (ICC) of 1-h consecutive recording periods. All variables except gap time showed acceptable reliability (ICC = 0.69-0.78), i.e. the largest fraction of variance in the data set was due to intersubject variance, despite relatively large hour-to-hour variation (CV = 0.21 0.62). The EMG activity level in the trapezius muscles was low (static activity level < 1% EMGmax), despite the high prevalence of shoulder and neck pain for both groups of workers. In addition to the work recordings, tests were performed to determine intersubject variation in muscle activity when adopting a standardized resting posture, and in a dynamic muscle activity pattern during paced arm movement. Neither the EMG variables from the work recordings nor the tests with EMG recording indicated higher trapezius EMG activity levels for workers with pain in the shoulders and neck in this study. The low EMG levels are interpreted to indicate a low risk of developing shoulder and neck complaints due to biomechanical exposure for both groups of workers. The possibility of pain-initiating mechanisms, associated with stress and not mediated through muscle activity, is considered in the discussion.     

Neck/shoulder and low-back disorders in the forestry industry: relationship to work tasks and perceived psychosocial job stress

In a national cross-sectional study, the prevalence of neck/shoulder and low-back disorders and their relationship to work tasks and perceived psychosocial job stress was studied among forestry employees. The data were collected by occupational health service staff using Karasek's demand/control questionnaire for the psychosocial measures and the Standardized Nordic questionnaire for the analysis of musculoskeletal disorders. Based on data about past and present work tasks, the study population was classified into three groups: 645 manual workers, 66 machine operators and 124 administrative workers. Low-back disorders were more common among the manual workers than among the administrative workers \[odds ratio (OR) = 1.98]. For the machine operators and manual workers, an increasing level of psychological demands was significantly associated with an increased prevalence of low-back disorders. The prevalence of neck/ shoulder disorders was significantly higher among the machine operators (OR = 3.37) and manual workers (OR = 2.34) than among the administrative workers. An increasing level of psychological demands combined with a decreasing level of intellectual discretion was associated with an increased prevalence of neck/shoulder disorders. Authority over decisions was not associated with musculoskeletal disorders. In conclusion, musculoskeletal disorders were associated with both physical and psychosocial work factors. The modest strength of the associations between each individual independent variable and the outcome measure shows, however, that a substantial reduction in the prevalence of musculoskeletal disorders may be difficult to achieve. Nevertheless, the study clearly suggests that in the forestry industry attention should be paid to psychosocial work factors in future organizational changes and preventive programmes.     

Risk of neck musculoskeletal disorders among males and females in lifting exertions

Work-related neck disorders are common among various occupational groups. Despite clear epidemiological evidence for the association of these disorders with forceful arm exertions, the effect of such exertions on the biomechanical behavior of the neck muscles is currently not well understood. In this study, the effect of lifting tasks on the biomechanical loading of neck muscles was investigated for males and females. Twenty-six participants (13 males and 13 females) performed bi-manual isometric lifting tasks at knuckle, elbow, shoulder, and overhead heights by exerting 25%, 50%, and 75% of their maximum strength. The activity of the cervical trapezius and sternocleidomastoid muscles was recorded bilaterally using surface electromyography. Higher activity of the cervical trapezius muscle (10% MVC–43% MVC) compared to the sternocleidomastoid muscle (4% MVC–18% MVC) was observed. Females tend to use the sternocleidomastoid muscle to a greater extent than males, whereas, higher cervical trapezius muscle activation was observed for males than females. The main effect of weight and height, and weight by height interaction on the activity of neck muscles was statistically significant (all p < 0.001). The results of this study demonstrate that the neck muscles play an active role during lifting activities and may influence development of musculoskeletal disorders due to resulting physiological changes.     

Relations between shoulder/neck disorders and EMG zero crossing shifts in female assembly workers using the test contraction method

Pain and discomfort in the shoulder/neck region is a serious problem amongst workers in many categories of assembly work. It has been suggested that these disorders are related to local muscular fatigue. In this study 14 female assembly workers were studied. Several of these women had occupational shoulder/neck disorders of various degrees. The method (FTC), applied during work, involved short test contractions every ten minutes during which EMG from m. trapezius and m. infraspinatus bilaterally was recorded. The EMG was analysed using the zero crossing technique. The subjects filled in a standard questionnaire concerning their muscular shoulder/neck disorders. It is shown that subjects reporting disorders have more pronounced EMG alterations than those without disorders.     

Musculoskeletal disorder prevalence and psychosocial risk exposures by age and gender in a cohort of office based employees in two academic institutions

This study presents data on self-reported prevalence of Musculo-Skeletal Disorder (MSD) symptoms and psychosocial risk exposures by age and gender among a group of office based University workers who use their computers for at least 25% of their workday. Employees in two academic organisations received an invitation to participate in an on-line questionnaire. A total of n = 852 office workers participated in this study; yet respondents who were employed for greater than 12 months were only included in the study cohort. Furthermore, participants were only considered for further analysis if they spent 50% or more of their workday in their office, and of this time at least 50% was spent on computer work (n = 569). The study indicates that self-reported symptoms of MSDs for these workers were highest in the neck, shoulder and lower back. Neck, shoulder and back MSDs were higher for females than males, yet age differences within genders were not evident for these symptoms. For neck disorders, symptomatic individuals reported significantly higher levels of office work (p < 0.05) and PC usage (p < 0.005), and significantly lower levels of job content (p < 0.01), job demands (p < 0.05), and work environment (p < 0.05) compared to asymptomatic participants. For the shoulder, symptomatic individuals exposure levels were significantly higher for office work (p < 0.05) and PC usage (p < 0.05) and significantly lower for job content (p < 0.05) compared to asymptomatic individuals. There was evidence of important differences in the psychosocial exposures between age and genders, but associations between these differences and MSD symptoms were not present.Relevance to industryThis study presents prevalence data on age and gender differences in self-reported symptoms of MSDs and psychosocial risk exposures in a group of sedentary workers.     

Associations of ergonomic and psychosocial work hazards with musculoskeletal disorders of specific body parts: A study of general employees in Taiwan

Background and aimsMusculoskeletal disorders (MSDs) are major occupational health concerns. This study examined the associations of ergonomic and psychosocial work hazards with the risks of MSDs of specific body parts and their distribution across a wide range of occupational groups.MethodsStudy participants comprised 8,937 male and 7,052 female employees aged 20–65 years from a nationwide survey in 2016. A self-report questionnaire was administered to obtain information regarding demographic characteristics, work conditions, ergonomic and psychosocial work hazards, and MSDs of different body parts in 12 months. Multivariate logistic regression models were used to estimate prevalence ratios of MSDs in relation to ergonomic and psychosocial work hazards.ResultsIn professionals and skilled workers, MSDs of the neck and shoulders were more prevalent, whereas in manual workers, MSDs of the hands, wrists, and lower back were more prevalent. Psychosocial work hazards, including high psychological demand and low workplace justice, were major work-related risk factors for shoulder and neck disorders, whereas ergonomic hazards were major work-related risk factors for lower back and wrist or hand disorders.ConclusionDifferent workplace hazards contribute to the risks of different MSDs. To prevent the development of MSDs, occupational health professionals should evaluate both ergonomic and psychosocial work hazards and develop health prevention programs tailored to the risk profiles of working populations.     

A comparison of muscle activity in using touchscreen smartphone among young people with and without chronic neck–shoulder pain

This study aimed to examine differences in muscle activity between young people with and without neck–shoulder pain (n = 20 in each group), when they performed texting on a smartphone. Texting was compared between using both hands (‘bilateral texting’) and with only one hand (‘unilateral texting’). Texting tasks were also compared with computer typing. Surface electromyography from three proximal postural muscles and four distal hand/thumb muscles on the right side was recorded. Compared with healthy controls, young people with neck–shoulder pain showed altered motor control consisting of higher muscle activity in the cervical erector spinae and upper trapezius when performing texting and typing tasks. Generally, unilateral texting was associated with higher muscle loading compared with bilateral texting especially in the forearm muscles. Compared with computer typing, smartphone texting was associated with higher activity in neck extensor and thumb muscles but lower activity in upper and lower trapezius as well as wrist extensors.     

Psychosocial risk exposures and musculoskeletal disorders across working‐age males and females

In 2008, The European Agency for Safety and Health at Work (EU‐OSHA) reported that musculoskeletal disorders (MSDs) were the most common work‐related health problem in Europe. Females are considered more susceptible to MSDs than are males, and older workers are more vulnerable than are younger workers. Factors specific to the job, work organization, and individual have been implicated as potential risk factors, with current interest focusing on psychosocial risk factors and the pathology of disorders. Although there is some disagreement in the literature, there is growing support that, after controlling for exposure, females have a predisposition to MSDs. More is known of the role of psychosocial risks in MSD etiology, but it is unclear if there are differences in exposures across gender and age and if this has a resultant effect on injury rates. The purpose of this study was to investigate the prevalence of MSDs and trends with psychosocial risks, across age and gender. The study group consisted of 200 female and 132 male employees from varied occupations within Ireland, ranging from age 18–66 years. The most prevalent symptoms of MSDs were for the lower back, shoulder, and neck regions. Age and gender differences in prevalence were evident for these regions. There was a general trend for increasing prevalence with age. For the psychosocial risks, significant differences in job content exposures were observed across age groups for males (p < 0.05) and females (p < 0.0005). There were also differences in scores across the age groups for mental health (p < 0.0005) and insecurity at work (p < 0.0005) for the females. The conclusions are that there were not sufficiently strong differences in exposures to relevant psychosocial risks both between genders and across age for a resultant effect on MSDs. © 2010 Wiley Periodicals, Inc.     

The combined effect of physical,psychosocial/organisational and/or environmental risk factors on the presence of work-related musculoskeletal symptoms and its consequences

This study assessed the combined effect of physical and psychosocial/organisational and/or environmental factors on the presence of musculoskeletal symptoms (MSS) and its consequences (reduced activities and absenteeism due to MSS) in a random sample of 3003 workers in New Zealand. By telephone interview, participants reported their current workplace exposures and MSS (neck/shoulder, arm/elbow, wrist and low back) and its consequences. Data were analysed using multivariable logistic regression. Combined exposure to physical and psychosocial/organisational and/or environmental factors increased the odds of MSS in the neck/shoulder (OR 3.14, 95% CI 1.79–5.52), arms/elbow regions (OR 4.14, 95% CI 2.21–7.76) and low back (OR 1.74, 95% CI 1.28–2.37) and its consequences, i.e. reduced activities due to neck/shoulder symptoms (OR 5.45, 95% CI 2.28–13.00), absenteeism due to neck/shoulder symptoms (OR 5.19, 95% CI 2.24–12.01) and absenteeism due to low back symptoms (OR 4.37, 95% CI 2.92–6.53). In contrast, favourable psychosocial/organisational work conditions reduced the odds of wrist symptoms due to poor physical work conditions (OR 2.19, 95% CI 1.44–3.34). We conclude that to reduce MSS and its consequences, employers need to adopt a multifaceted approach: concentrate on improving physical conditions as well as the psychosocial/organisational and environmental aspects of the working environment.     

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.     

Gender analysis of musculoskeletal disorders and emotional exhaustion: interactive effects from physical and psychosocial work exposures and engagement in domestic work

The objective of this study was to assess the relationships between physical and psychosocial work exposures, engagement in domestic work and work-home imbalance in relation to symptoms of musculoskeletal disorders and emotional exhaustion in white- and blue-collar men and women. Three thousand employees from 21 companies were asked to answer a questionnaire on family structure, household and child care tasks, work exposure, work-home imbalance and symptoms of neck/shoulder disorders, low back disorders and emotional exhaustion. Women reported more musculoskeletal disorders and engagement in domestic work. Adverse at-work exposures were highest in blue-collar women. High engagement in domestic work was not separately associated with symptoms but paid work exposure factors were associated. High engagement in domestic work interacted with adverse work exposure and increased risk estimates for low back disorders and emotional exhaustion. Reported work-home imbalance was associated with neck/shoulder disorders in women and with emotional exhaustion in both women and men. PRACTITIONER SUMMARY: The current article adds to earlier research by showing that high engagement in domestic work is not separately associated with increased symptoms, but interacts with psychosocial work exposure variables to produce emotional exhaustion in both women and men and low back disorders in women.     

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.     

Work-related musculoskeletal complaints: some ergonomics challenges upon the start of a new century

Three themes likely to be important within health-related ergonomics in the coming years are discussed. The first two themes concern methods for risk analysis of low-level biomechanical and psychosocial exposures. The third theme is approaches to successful implementation of ergonomics interventions. Evidence on the assessment of low-level biomechanical and psychosocial exposures by instrumented measurements is discussed. It is concluded that, despite recent advances in our understanding of exposure-effect associations under these exposure conditions, we must at present rely on more subjective methods, employed in a collaboration between expert and worker. This approach to risk analysis identifies in most cases critical exposures in a work situation. The focus should then be on the successful implementation of measures against those exposures, as identification alone does not solve problems. The aim of improved health for the workers further requires that the full complement of risk factors be considered, including work, leisure time and person-based risk factors. Finally, the need to put ergonomics intervention initiatives in an organisational context is emphasised, and examples of approaches used by Norwegian companies are presented.     

Electromyographic fatigue in neck/shoulder muscles and endurance in women with repetitive work.

EMG was recorded with surface electrodes from the trapezius and deltoid muscles during a static endurance test at approximately 20% of maximal voluntary contraction. Objective parameters for localized muscular fatigue were derived from the time course of the root mean square (RMS) and mean power frequency (MPF) of the EMG recordings. Isotonic regression is introduced as a tool for assessment of such parameters. The most pronounced sign of fatigue for trapezius was an increase in the RMS values, while for deltoid it was a decrease in the MPF values. This could be explained by the different functions of the two muscles. The endurance time for a group of 11 women in industrial work with repetitive short-cycled work tasks who were diagnosed with neck/shoulder disorders (tension neck) was significantly shorter (p less than 0.05) than for a group with the same work, but without neck/shoulder disorders (n = 11), and shorter than for a control group (n = 11). Regarding the EMG fatigue measures, there were no significant differences between the three groups. We did not find any relationships between endurance time and the EMG parameters. The results indicate that neck/shoulder disorders were not associated with divergent mechanisms for developing fatigue in the muscles, as recorded with surface EMG.     

Acceptable muscle load on the neck and shoulder regions assessed in relation to the incidence of musculoskeletal sick leave: Implications for human‐computer interaction

A threshold level for acceptable load on the musculoskeletal system of the neck and shoulder regions was explored by studying comparable groups of female workers with different development of musculoskeletal sick leave in these areas. The load on the neck and shoulder was assessed by recording electromyography (EMG) from m. trapezius (descending part). The quantitative analysis of the trapezius load was carried out by calculating the number and total duration of periods below 5% MVC (Maximum Voluntary Contraction), 8% MVC, and 10% MVC. To relate acceptable musculoskeletal load to health criteria such as acceptable limits for development of musculoskeletal illness in a group of workers, the incidence of musculoskeletal illness for the comparable groups was also compared with a control group of female workers without a continuous work load. Two groups of workers had a development of musculoskeletal sick leave, which was approximately the same as the incidence of such illness for the control group. The trapezius load for these groups was below 5% MVC for about 40% of the working time. By comparing the groups of workers with different development of musculoskeletal sick leave, the trapezius load differed only for load levels below 5% MVC; increasing duration of load levels below 5% MVC was associated with lower incidence of musculoskeletal sick‐leave. The results indicated that trapezius load below 5% MVC was important to reduce the incidence of load‐related musculoskeletal illness.