Psychophysiological stress reactions,trapezius muscle activity,and neck and shoulder pain among female cashiers before and after introduction of job rotation

The aim of this study was to evaluate the effects of the introduction of a job rotation model on supermarket cashiers, with respect to psychophysiological stress reactions, muscle activity of the trapezius muscle (which covers the upper back, the neck and the shoulder), and musculoskeletal symptoms in the neck and shoulders. Thirty-one female cashiers were investigated before and after job rotation was introduced. Before the reorganization the participants were only performing cash register work at the checkout counters. After the reorganization they shifted between cash register work and work in different departments in the supermarket. At follow-up the participants, all right-handed, had a significantly lower diastolic blood pressure, and surface electromyography (EMG) showed a significantly decreased muscle activity in the trapezius muscle on the left side. Musculoskeletal symptoms of the neck and shoulders were only partly changed, and there was no change in prevalence of musculoskeletal pain, which was around 70%. From questionnaires, but not from self-ratings during work, it was found that the introduction of job rotation had been experienced as positive in several regards, although the perceptions of stress and hurry were the same at follow-up.     

Work-related psychosocial,physical and individual factors associated with musculoskeletal symptoms in computer users

The aim of this study was to study associations between psychosocial, physical and individual factors, and musculoskeletal symptoms in the neck, shoulder and hand/wrist regions of computer users. Questionnaires were distributed to 5033 employees in 11 Danish companies; these employees all used computers for at least some of their work time. The response rate was 69% ( n = 3475). The analyses were based on employees working 32-41 h/week ( n = 2579). Symptomatic respondents reported symptoms for at least 8 days within the previous year. Multiple logistic regression analyses were used. Gender (female), age and duration of employment in the same job were associated with an increased prevalence of symptoms. High quantitative job demands and low possibilities for development at work were predictors of neck and hand/wrist symptoms. A high degree of repetitiveness and disturbing reflections on the computer screen were associated with symptoms in all three body regions. Repetitive movements were defined as the same finger, hand or arm movements performed many times per minute for at least 75% of their work time. Repetitiveness was the only factor that could partly explain associations between symptoms and duration of computer use, i.e. respondents who used the computer almost all the time at work reported more repetitive movements than those who used it less. Thus, long hours of computer use may be associated with musculoskeletal symptoms, due to physical factors such as repetitive movements, whereas psychosocial factors appeared to be associated with the symptoms independently of the duration of computer use.     

Work-related psychosocial, physical and individual factors associated with musculoskeletal symptoms in computer users

The aim of this study was to study associations between psychosocial, physical and individual factors, and musculoskeletal symptoms in the neck, shoulder and hand/wrist regions of computer users. Questionnaires were distributed to 5033 employees in 11 Danish companies; these employees all used computers for at least some of their work time. The response rate was 69% ( n = 3475). The analyses were based on employees working 32-41 h/week ( n = 2579). Symptomatic respondents reported symptoms for at least 8 days within the previous year. Multiple logistic regression analyses were used. Gender (female), age and duration of employment in the same job were associated with an increased prevalence of symptoms. High quantitative job demands and low possibilities for development at work were predictors of neck and hand/wrist symptoms. A high degree of repetitiveness and disturbing reflections on the computer screen were associated with symptoms in all three body regions. Repetitive movements were defined as the same finger, hand or arm movements performed many times per minute for at least 75% of their work time. Repetitiveness was the only factor that could partly explain associations between symptoms and duration of computer use, i.e. respondents who used the computer almost all the time at work reported more repetitive movements than those who used it less. Thus, long hours of computer use may be associated with musculoskeletal symptoms, due to physical factors such as repetitive movements, whereas psychosocial factors appeared to be associated with the symptoms independently of the duration of computer use.     

Psychological stress and muscle activity during data entry at visual display units

Abstract

The aim of this study was to evaluate whether psychological stress causes increased muscle activity, especially static muscle activity, in the trapezius muscles of the neck and shoulder. A pilot and a main study were carried out with 10 males and 20 females, respectively. The subjects performed a VDU data entry task under psychologically stressful and non-stressful conditions. Stress reactions were measured by different methods: heart rate and heart rate variability, hormonal excretion, and subjective ratings of mood and body symptoms. The stress condition caused an increase in heart rate. The low-frequency variability increased and the high-frequency variability decreased. Ratings of motivation and relaxation decreased, and subjects felt more activated. Pain and discomfort from the stomach increased. Adrenaline and noradrenaline in urine were unaffected. The majority of the subjects showed moderately increased static and median EMG levels during the stress condition. The interindividual variation in muscular reactions was large. Statistically significant increases were obtained for the myoelectric activity of the left (resting) trapezius muscle when pooling the two groups. It appears that the increase in muscle activity due to this type of mental stress is small, and factors other than ‘attention-related’ load may be more important. The results indicate that some individuals may be more prone to general muscle tension, making them more likely to develop symptoms and musculoskeletal pain.     

Musculoskeletal discomfort and work-related stress in New Zealand dentists

There has been little research into the stressors, psychological distress and musculoskeletal symptoms experienced by dentists. The present study was carried out among a random sample of New Zealand dentists (N=413). The present study aimed to identify the severity of work psychosocial stressors, examine the occurrence of musculoskeletal discomfort and psychological disturbance, and determine relationships between these factors. The average age of the dentists was 43 years, with 74% being male. The annual prevalence of symptoms in both the lower back or neck was 63%, with 49% experiencing symptoms in the shoulders. Older dentists were no more likely to suffer musculoskeletal discomfort than younger dentists. The highest ranking dentistry-specific work-related stressor was 'patients having a medical emergency' with 78% scoring this stressor very highly. Dentists scored mental demands as the highest general work-related stressor. One-fifth of the dentists scored highly for psychological disturbance, which was very similar to the general population. Dentists with high scores for dentistry-specific work-related stressors were more likely to have evidence of psychological disturbance. The relationships between psychological disturbance and musculoskeletal discomfort needs to be taken into account when considering any multidisciplinary approach to prevention.     

The impact of VDU use and psychosocial factors at work on musculoskeletal shoulder symptoms among white-collar workers

This investigation of white-collar workers ( n = 201) in Swedish industrial environments focused on an empirical examination of the relationships between work with visual display units (VDUs), psychosocial factors (skill discretion, appraised work load, job satisfaction), physical work load and musculoskeletal shoulder symptoms. This cross-sectional study was based upon questionnaire surveys carried out at industrial companies. The prevalence of shoulder symptoms during the previous year was 39%. Nearly one-half of the participants reported that they used a VDU for at least 4 h/day ('high VDU use'). High VDU use was related to increased Prevalence Odds Ratio (POR) for shoulder symptoms. After adjustment for physical work load, significant PORs were found in groups with high VDU use in combination with low job satisfaction (POR = 4.8) or high appraised work load (POR = 3.5), compared to groups with low VDU use in combination with high job satisfaction or low work load (reference groups).     

Musculoskeletal discomfort and work-related stress in New Zealand dentists

Abstract

There has been little research into the stressors, psychological distress and musculoskeletal symptoms experienced by dentists. The present study was carried out among a random sample of New Zealand dentists (N=413). The present study aimed to identify the severity of work psychosocial stressors, examine the occurrence of musculoskeletal discomfort and psychological disturbance, and determine relationships between these factors. The average age of the dentists was 43 years, with 74% being male. The annual prevalence of symptoms in both the lower back or neck was 63%, with 49% experiencing symptoms in the shoulders. Older dentists were no more likely to suffer musculoskeletal discomfort than younger dentists. The highest ranking dentistry-specific work-related stressor was ‘patients having a medical emergency’ with 78% scoring this stressor very highly. Dentists scored mental demands as the highest general work-related stressor. One-fifth of the dentists scored highly for psychological disturbance, which was very similar to the general population. Dentists with high scores for dentistry-specific work-related stressors were more likely to have evidence of psychological disturbance. The relationships between psychological disturbance and musculoskeletal discomfort needs to be taken into account when considering any multidisciplinary approach to prevention.     

Effects of experimentally induced mental and physical stress on motor unit recruitment in the trapezius muscle

Mental stress may induce muscle tension and it is thought to contribute to the development of musculoskeletal disorders. Prolonged activity of a muscle's motor units (the smallest functional units) having low activation thresholds, may cause metabolic disturbances, degenerative processes and pain. The present experiment was aimed at investigating if the same motor units are activated by mental stress as by physical demands. Seventeen participants were exposed to mental stress tests (mental arithmetic, Stroop color word) and physical demands (standardized reference contraction, force ramp contraction) in the laboratory. In addition, they were exposed to the cold pressor test. Bipolar intramuscular electromyographic (EMG) activity was measured in the trapezius muscle, which covers the upper part of the back, the neck and the shoulder, and an automatic classification programme was used to separate the contributions of the individual motor units in the compex EMG signal. Overall muscle activity was measured by bipolar surface EMG and heart rate was recorded as an indicator of stress. The mental stress induced significant increases in muscle activity ( p < .05) and in heart rate ( p < .05). In 12 out of 14 participants, one or more motor units were found to be active in mentally as well as in physically induced muscle contraction. The results indicate that mentally induced stress may contribute to keeping low threshold motor units active, even in the absence of physical demands. Considering the health risks of prolonged motor unit activity, it was concluded that lack of mental rest is an important risk factor for the development of muscular pain.     

Musculoskeletal problems in bricklayers as a function of length of employment: The role of secondary selection by low-back pain

Low-back problems that are caused by heavy physical work should increase with the length of employment. In a cross-sectional study 195 bricklayers were interviewed and subjected to a medical examination concerned with complaints and functional impairments of the musculoskeletal systems of different body regions (neck/shoulder, arms/hands, back, hip/legs/feet). Summary variables for complaints and impairments indicated an increase with increasing age. Contrary to expectation, in pairs of bricklayers of the same age, but different length of employment, a general decline of complaints and impairments with longer employment was observed. This finding suggested a healthy worker effect. In a follow-up the turnover rate among 190 of the 195 bricklayers of the original study was determined. Bricklayers who had quit the job had a higher incidence of low-back troubles before leaving than bricklayers who had stayed in the job; the relation between turnover and low-back problems was limited to bricklayers older than about 40 years.     

Musculoskeletal problems in bricklayers as a function of length of employment: The role of secondary selection by low-back pain

Abstract

Low-back problems that are caused by heavy physical work should increase with the length of employment. In a cross-sectional study 195 bricklayers were interviewed and subjected to a medical examination concerned with complaints and functional impairments of the musculoskeletal systems of different body regions (neck/shoulder, arms/hands, back, hip/legs/feet). Summary variables for complaints and impairments indicated an increase with increasing age. Contrary to expectation, in pairs of bricklayers of the same age, but different length of employment, a general decline of complaints and impairments with longer employment was observed. This finding suggested a healthy worker effect. In a follow-up the turnover rate among 190 of the 195 bricklayers of the original study was determined. Bricklayers who had quit the job had a higher incidence of low-back troubles before leaving than bricklayers who had stayed in the job; the relation between turnover and low-back problems was limited to bricklayers older than about 40 years.     

Editorial: Cognitive science,occupational stress and organizational health

A number of studies have shown that musculoskeletal symptoms are related to the physical and psychosocial work environments. Workers with musculoskeletal symptoms are often advised to cope by such measures as changing working technique, using lifting equipment and discussing health and environmental problems with supervisors and colleagues. Intervention studies at the individual level, however, have shown that such advice has limited effects in reducing the prevalence of musculoskeletal symptoms. The hypothesis for this study was that negative social and organizational factors may prevent workers from implementing such coping strategies. All 103 motor vehicle mechanics surveyed in 12 different garages responded to a questionnaire on coping with musculoskeletal symptoms and the psychosocial work environment. Positive and significant relationships were shown between how mechanics coped with their musculoskeletal symptoms and such psychosocial factors as work demands, social support, control, manager's involvement in health and safety work, and whether the garages had regular meetings between management and workers. Achieving positive results from preventive work through back schools and other ergonomic interventions seems to require that an organization with positive attitudes towards health and safety work be created before such interventions are implemented.     

Psychosocial stress and job satisfaction in female office employees with and without neck-shoulder symptoms

The objective of this research performed in a Finnish occupational health care setting was to describe the annual prevalence of neck and shoulder symptoms in female office employees and to test whether or not these symptoms were associated with psychosocial stress, job satisfaction and health locus of control. The subjects consisted wholly of female office employees (n = 232) at one local bank and three insurance offices, chosen on a voluntary basis. The annual prevalence of disturbing neck-shoulder symptoms among female office employees was 43.3%. An association of these symptoms with psychosomatic symptoms, poor general job satisfaction and its two subdimensions, work content and perception of the healthiness of the working environment, was noticed. The subjects with neck-shoulder symptoms had a significantly higher score of feelings of external control (fatalism) than those without symptoms. The results lead to the conclusion that neck-shoulder symptoms are common amongst female office employees. These symptoms are associated with some psychosocial stress factors and job dissatisfaction. In future, it would be important to pay attention to these factors when trying to reduce the prevalence of neck-shoulder symptoms in office work.     

Women,men, VDU work and health: A questionnaire survey of British VDU operators

Abstract

This paper presents the results of a questionnaire survey of male and female VDU operators distributed through Health & Safety at Work magazine. 3819 questionnaires were analysed using the SPSS computer program. 57% of the sample were female, 68% were under 35 years old and 73% were members of a trade union or staff association. The large number of male respondents meant that it was possible to compare work patterns, types of work and health effects for men and women. It appears that women are engaged in more repetitive and less varied tasks at the VDU and that they work longer hours and for longer periods without a break than men. The most frequently reported health problems were eyestrain, painful or stiff neck and shoulders, fatigue and irritated eyes. The incidence of symptoms was related to hours of work at the VDU. Women were more likely to report health effects than men. This difference remains when hours of work, type of work and hours worked without a break are taken into account. Ergonomically designed equipment such as adjustable chairs, lighting or keyboard did not have an obvious effect on the reporting of symptoms. It appeared that there is a complex interaction between the physical, ergonomic and psychosocial factors associated with new technology. All these factors need to be taken into account in further research into the health problems of VDU operators.     

The Japanese version of the Effort-Reward Imbalance Questionnaire: a study in dental technicians

To test the psychometric properties and criterion validity of the Japanese version of the EffortReward Imbalance (ERI) Questionnaire (Siegrist, 1996), a survey was conducted among 105 male dental technicians. The Japanese version of the questionnaire was developed through a backtranslation process. Internal consistency and factorial structure were tested and the criterion validity with respect to musculoskeletal symptoms was estimated with the help of a correlation matrix and logistic regression analysis. In psychometric terms, the factorial structure of the scales measuring the components of the theoretical concept was replicated satisfactorily, and internal consistencies of the scales measuring the extrinsic and intrinsic components of the model were appropriate. Significant associations between components of the ERI and musculoskeletal symptoms were found. Logistic regression analysis revealed a significantly elevated risk of musculoskeletal symptoms in participants scoring high on the scale measuring the model's intrinsic component, 'overcommitment'. This study indicates that, at least for the occupational group under study, the Japanese version of the ERI Questionnaire is a feasible and psychometrically well justified new measure for assessing psychosocial stress at work with relevance to health.     

The Effects of Task Clarification and Group Graphic Feedback on Early Punch-In Times

Task clarification in the form of workplace policy guidelines coupled with weekly graphic feedback of group punch-in times on the staff clock were presented to waitstaff, cooks, cash register clerks, dishwashers, buffet attendants, and hourly assistant managers in a restaurant sub-franchise. Clocking in early dropped from 130 min during baseline to 62 min per week during intervention. A 1-week return to baseline resulted in 189 min of clocking in early by restaurant personnel. The use of task clarification and group feedback reduced company expenses without reductions in job satisfaction or increased stress.     

Women, men, VDU work and health: A questionnaire survey of British VDU operators

This paper presents the results of a questionnaire survey of male and female VDU operators distributed through Health & Safety at Work magazine. 3819 questionnaires were analysed using the SPSS computer program. 57% of the sample were female, 68% were under 35 years old and 73% were members of a trade union or staff association. The large number of male respondents meant that it was possible to compare work patterns, types of work and health effects for men and women. It appears that women are engaged in more repetitive and less varied tasks at the VDU and that they work longer hours and for longer periods without a break than men. The most frequently reported health problems were eyestrain, painful or stiff neck and shoulders, fatigue and irritated eyes. The incidence of symptoms was related to hours of work at the VDU. Women were more likely to report health effects than men. This difference remains when hours of work, type of work and hours worked without a break are taken into account. Ergonomically designed equipment such as adjustable chairs, lighting or keyboard did not have an obvious effect on the reporting of symptoms. It appeared that there is a complex interaction between the physical, ergonomic and psychosocial factors associated with new technology. All these factors need to be taken into account in further research into the health problems of VDU operators.     

Changes in mental well-being, blood pressure and total cholesterol levels during workplace reorganization: the impact of uncertainty

The aim of this study was to investigate the effects of uncertainty caused by large-scale workplace reorganization, on psychological well-being, blood pressure and total cholesterol levels. Employees (98 women and 86 men) were assessed four times, at approximately 6-monthly intervals, twice before and twice after reorganization. Self-reported psychological well-being was at its lowest level shortly prior to reorganization, as predicted. Greater self-reported uncertainty about one's own future occupational situation was associated with a bigger reduction in mental well-being before reorganization, as was role ambiguity after reorganization. Systolic blood pressure was elevated over initial levels just prior to reorganization, and shortly after reorganization, but at the final assessment was not significantly different from initial levels. A bigger increase in systolic blood pressure was seen in those reporting greater future job uncertainty before reorganization, and in those who started a new job or who reported greater role ambiguity after reorganization. Diastolic blood pressure was also significantly elevated over initial levels just before reorganization, but this effect became nonsignificant once changes in body mass index were statistically controlled. Total cholesterol also reached its highest level just prior to reorganization, but this effect was not significant. It is concluded that workplace reorganization caused significant increases in distress and in systolic blood pressure and that uncertainty contributed to these effects.     

The Japanese version of the Effort-Reward Imbalance Questionnaire: A study in dental technicians

To test the psychometric properties and criterion validity of the Japanese version of the EffortReward Imbalance (ERI) Questionnaire (Siegrist, 1996), a survey was conducted among 105 male dental technicians. The Japanese version of the questionnaire was developed through a backtranslation process. Internal consistency and factorial structure were tested and the criterion validity with respect to musculoskeletal symptoms was estimated with the help of a correlation matrix and logistic regression analysis. In psychometric terms, the factorial structure of the scales measuring the components of the theoretical concept was replicated satisfactorily, and internal consistencies of the scales measuring the extrinsic and intrinsic components of the model were appropriate. Significant associations between components of the ERI and musculoskeletal symptoms were found. Logistic regression analysis revealed a significantly elevated risk of musculoskeletal symptoms in participants scoring high on the scale measuring the model's intrinsic component, 'overcommitment'. This study indicates that, at least for the occupational group under study, the Japanese version of the ERI Questionnaire is a feasible and psychometrically well justified new measure for assessing psychosocial stress at work with relevance to health.     

How the psychosocial work environment of motor vehicle mechanics may influence coping with musculoskeletal symptoms

A number of studies have shown that musculoskeletal symptoms are related to the physical and psychosocial work environments. Workers with musculoskeletal symptoms are often advised to cope by such measures as changing working technique, using lifting equipment and discussing health and environmental problems with supervisors and colleagues. Intervention studies at the individual level, however, have shown that such advice has limited effects in reducing the prevalence of musculoskeletal symptoms. The hypothesis for this study was that negative social and organizational factors may prevent workers from implementing such coping strategies. All 103 motor vehicle mechanics surveyed in 12 different garages responded to a questionnaire on coping with musculoskeletal symptoms and the psychosocial work environment. Positive and significant relationships were shown between how mechanics coped with their musculoskeletal symptoms and such psychosocial factors as work demands, social support, control, manager's involvement in health and safety work, and whether the garages had regular meetings between management and workers. Achieving positive results from preventive work through back schools and other ergonomic interventions seems to require that an organization with positive attitudes towards health and safety work be created before such interventions are implemented.     

The influence of psychological stressors on myoelectrical signal activity in the shoulder region during a data entry task

Psychological stress is suspected to play a key role in the development of work-related musculoskeletal disorders (WMSDs), and work pace may be a primary contributor. The purpose of this study was to observe how psychological stress affects muscle activity recorded from key muscles used to support the shoulder (the trapezius and levator scapulae muscles) during keying tasks. We hypothesized that muscle activity [amplitude of the myoelectric signal (MES)] would increase and the number of periodic rests in muscle activity ('EMG gaps') would decrease when computer work was performed at an increased pace, and with distractions in the environment. Ten healthy volunteers performed three typing tasks (N = no stress; I = stress induced by a work pace reward; IS = stress induced by a work pace reward plus irritation/distraction). Both muscles showed significant increases ( p < .05) in MES amplitude when comparing IS to the N and I conditions, whereas N and I were not different. There was significant reduction in the number of gaps observed during the I and IS conditions (essentially no gaps were observed) as compared to the N condition. Interestingly, MES amplitude measures were capable of preferentially detecting changes in activation due to the distraction stress, whereas the number of EMG gaps preferentially detected the stress of the increase in work pace. The effect of these stressors on heart rate and productivity are also discussed.