[Psychogenic muscular activity as a risk factor of muscular pain]

Recent research indicates that any continuous load on the shoulder and upper limb muscles is a risk factor for occupational muscle pain. When the muscle load is moderate to low, the duration seems far more important than the actual load level, possibly because of a fixed recruitment order of motor units. Research at the Norwegian National Institute of Occupational Health has shown that a mentally challenging task at a visual display terminal may give a low level of muscle activation with apparently no purpose as regards posture or movement ("psychogenic" muscle tension), based on continuous firing in a few motor units. This indicates a possible mechanism for the often observed link between psychosocial stress and muscle pain.

Self-reported musculoskeletal pain and discomfort in professional ballet dancers in Sweden

One hundred and forty-seven professional dancers belonging to the three major companies in Sweden were asked to fill out a standardized questionnaire about musculoskeletal trouble and their work situation. This study details the answers and suggests ways of dealing with this particular work situation. Of the 128 dancers who answered the questionnaire, 121 had experienced trouble some time during the preceding 12 months. The low back was the site provoking most complaints (70%) followed by complaints from ankles/feet (65%) and neck (54%). There were no significant differences between the sexes. Trouble during the preceding 7 days in ankles/feet and low back had been experienced by 30% and 27% of the dancers, respectively. Ankles/feet trouble had kept dancers from their daily work in 54% of the cases, while low back trouble had prevented them from working to a lesser extent (40%) and neck trouble even less so (20%). Of the total 472 problems, 168 (36%) had prevented the dancers from doing their daily work. The answers to what they thought caused their problems to increase and decrease were later categorized as either physical, psychosocial or environmental. Most of the circumstances believed to increase trouble were related to poor training, while the ways to decrease trouble were mostly related to passive therapeutic treatments.

Prospective study on the relationship between depressive symptoms and chronic musculoskeletal pain

Chronic pain and depression often coexist, but there is still uncertainty about the nature of this relationship. Virtually all the available data are cross-sectional and therefore do not clarify the causal relationship between the two variables. In epidemiological studies, chronic pain has often been defined fairly liberally in terms of the actual duration. In this study, the definition of chronic pain was based upon self-reports of pain present for most of the days in at least 1 month of the 12 months preceding the interview. We tested the hypotheses that depression causes pain and that pain causes depression in a sample of 2324 subjects who were assessed for the presence of musculo-skeletal pain and the presence of depression, using for the latter a standardized published instrument called the Center for Epidemiologic Studies Depression scale (CES-D). The subjects were first examined using the National Health and Nutrition Survey (NHANES 1) of the United States National Center for Health Statistics from 1974 to 1975, and were followed-up from 1981 to 1984. Those with data on both occasions represent 76% of an initial population of 3059 persons. On logistic regression analysis depressive symptoms at year 1 significantly predicted the development of chronic musculo-skeletal pain at year 8 with an odds ratio of 2.14 for the depressed subjects compared with the non-depressed subjects. In patients in whom pain was present at baseline no socio-demographic variable alone predicted its persistence; however, male sex and white race together with 2 items of the CES-D did predict the persistence of existing pain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Connections between musculoskeletal complaints and personality]

Modern research has demonstrated a weak association between level of muscle tension and experience of muscle pain. Anxiety and dysphoric over-responsiveness are the traditional psychogenic risk factors in muscle tension. Results from recent Norwegian research lend support to a more multidimensional causal understanding of muscle tension and of pain. Generally, personality factors were found to be a contributory cause of muscle pain of the neck and shoulders, whereas ergonomic load was found to be of greater significance for low back pain. Personality factors may induce patterns of skeletal muscle activation discrepant with characteristics of the skeletal muscle physiology: Preference for aerobic activities may develop through social learning, whereas the muscles may be genetically biased toward anaerobic activities. Furthermore, personality factors may be challenged by the work setting, and may result in mismatch that provokes muscle pain. Impatient expenditure of effort has appeared as a mediating personality risk factor among workers exposed to high ergonomic load, whereas dysphoric over-responsiveness mediated back pain primarily among staff exposed to high emotional load.

[Health effects of physical activity and psychological training]

Skeletomuscular pain is a very frequent complaint. Most patients recover spontaneously, but in some this pain may become long-lasting or even chronic. This occurs only in a minority, but even so skeletomuscular pain is the most frequent reason for long-term sickness benefit and permanent disability in the present Norwegian population. This report reviews the results of a series of controlled studies in Norway demonstrating that such pain may be treated by several different methods. Positive effects have been demonstrated from aerobic physical training, stress management training, relaxation training, and combinations of these programmes. Interventions directed at the organisation of the work situation have also had positive effects. These effects include decrease of pain and of psychological and subjective health complaints. However, a comparison of the effects of the different types of treatment would have to be based on a large multicentre study.

Psychosocial factors at work and musculoskeletal disease

The objective of this review is to establish whether the epidemiologic literature presents evidence of an association between psychosocial work factors and musculoskeletal disease. In a hypothetical model it is suggested that individual characteristics and stress symptoms can modify this relationship. The reviewed studies do not present conclusive evidence due to high correlations between psychosocial factors and physical load and to difficulties in measuring dependent and independent variables. Nevertheless, it is concluded that monotonous work, high perceived work load, and time pressure are related to musculoskeletal symptoms. The data also suggest that low control on the job and lack of social support by colleagues are positively associated with musculoskeletal disease. Perceived stress may be an intermediary in this process. In addition, stress symptoms are often associated with musculoskeletal disease, and some studies indicate that stress symptoms contribute to the development of this disease.

Muscle coordination and choice-reaction time tests as indicators of occupational muscle load and shoulder-neck complaints

The use was explored of psychomotor tests as indicators of the risk of shoulder-neck disorders in workers with low-level static loads on the shoulder muscles. Two groups of workers performing office work and light production work were studied. A muscle coordination test with continuous movement of the arm and hand between three target areas and a psychogenic tension test, posing mental demands and with minimal requirement for body movements, aimed to quantify muscle activity in excess of that needed for biomechanical purposes. The electromyogram (EMG) recording of the active trapezius muscle in the muscle coordination test correlated with the median and static EMG values of the vocational (i.e. during the normal work task) trapezius recording both for the office and production workers, but showed no correlation with shoulder-neck complaints. The EMG responses in the psychogenic tension test and of the passive (contralateral) trapezius in the muscle coordination test correlated best with the parameters showing short, spontaneous pauses in the EMG recording of occupational load. For the office workers, but not for the production workers these parameters also correlated with shoulder-neck complaints and the presence of psychosocial problems. Psychomotor tests may thus be useful as indicators of the risk of shoulder-neck complaints in certain occupations, but further experimentation is needed to validate this conclusion.

Chronic musculoskeletal pain and depressive symptoms in the National Health and Nutrition Examination. I. Epidemiologic follow-up study

We report here follow-up data on subjects who were examined in two surveys conducted by the United States Center for Health Statistics at an interval of 8 years. The first survey was the 1st National Health and Nutrition Examination Survey (NHANES-1), and the second conducted 8 years later was the National Health and Nutrition Epidemiologic Follow-up Study (NHEFS). From an original sample of 3023 subjects, 153 were known to be deceased, leaving a potential sample of 2870 cases, of whom 2341 were ultimately examined in the NHEFS. The definition of pain used in the NHANES-1 survey identified 15% of the subjects as suffering from persistent pain. Using a different pain definition, in the NHEFS, the frequency of subjects with chronic pain was 32.8%. Applying this second definition, the percentage of subjects with chronic pain in the NHANES-1 had risen from 15 to 20.2. Some subjects (32.5%) who originally had chronic pain were free from pain at the time of follow-up; 59% of the subjects with chronic pain on follow-up did not have it initially. As found originally in the NHANES-1, the group with chronic pain at the NHEFS comprised significantly more females, older people, and people with lower income. On logistic regression analysis the strongest relationship found at the NHEFS between the variables examined was between chronic pain and depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Depressive and distress symptoms as predictors of low back pain, neck-shoulder pain, and other musculoskeletal morbidity: a 10-year follow-up of metal industry employees

Six-hundred-seven employees in 3 metal industry plants were studied for depressive and distress symptoms, musculoskeletal symptoms, and findings in the musculo-skeletal system made by a physiotherapist. Measurements were made 3 times at 5-year intervals. The mean distress and depressive symptom scores of the first 2 examinations predicted the change in several musculo-skeletal symptom measures during the second 5-year period, when the effects of age and occupational class were accounted for in multiple regression analysis. They also predicted the development in clinical musculoskeletal findings in men. The proportions of variance explained by the depressive and distress symptoms were modest in magnitude. Analogous analyses were made with reference to the reverse temporal sequence: musculoskeletal disorders were considered as predating the development in depressive and distress symptoms. The musculoskeletal symptom scores were associated with the change in the stress symptoms in men, as did the clinical findings in the neck-shoulder and low back regions. None of the musculoskeletal morbidity scores predicted the change in the depressive symptoms in either sex. We conclude that depressive symptoms predict future musculoskeletal disorders, but not vice versa, whereas the association of stress symptoms and musculoskeletal disorders is reciprocal.

Arthritis education: opportunities and state of the art

Health education research in arthritis and musculoskeletal disease experienced extraordinary growth in the 1980s. In this article we discuss opportunities for health education in arthritis and musculoskeletal disease, and the effectiveness of evaluated programs to influence knowledge, behavior, and health status of persons with arthritis. Additionally, we review developments in theory and trends in research that we expect to be influential in the next decade. Educational opportunities for primary prevention of arthritis are limited. However, a large variety of organized programs, planned according to commonly accepted principles of education, psychology, and psychotherapy, and applied consistently by personnel with some kind of training, have been able to produce desirable changes in knowledge, behavior, and health outcome in arthritis patients, over and above the medical treatment and incidental education to which they have already been exposed. As a result, national dissemination of programs and standards for arthritis patient education is in progress. In the next decade, researchers will increasingly turn to new populations and methods of delivery, investigation of conditions less well studied, such as osteoporosis, education of patients in generic communication and coping skills, and development of arthritis-specific applications of theory, especially in areas such as social support, control and helplessness, cognitive processing, and pain management.

A three-year follow-up of 195 reported occupational over-exertion injuries

Three years after reporting occupational over-exertion injuries, 181 persons took part in a follow-up study by questionnaire. The objective was to study these persons with respect to their current status of health, well-being and functional capacity and when possible compare collected data to reference data from the "normal population". The studied group reported more physical and psychological symptoms than the reference groups. More than 50% reported difficulties in activities of daily living. Long sick-leaves in the year following the reported injury were associated with remaining pain and low rate of employment. Three years after the injury, 109 persons were in employment. Almost one third of these had changed occupations and now had more varied tasks than at the time of the report. Those whose work loads had been reduced after the injury, did not report less musculoskeletal disorders than others. However, access to social support was positively related with health and psychological well-being.

Individual and work-related risk factors associated with symptoms of musculoskeletal complaints

Individual and work-related risk factors in the development of occupational musculoskeletal complaints were investigated in a cross-sectional study of 52 female production workers and 34 female office workers. The work tasks of the production workers were considered to generate shoulder muscle loads of low amplitude and high repetitiveness, and the work tasks of the office workers, muscle loads of low amplitude and low repetitiveness. The symptom scores were similar in the two groups, with the highest score for both groups in the shoulder-neck region. Previous pain symptoms were an important risk factor for musculoskeletal pain in all body regions, whereas psychosocial problems at work were a risk factor for complaints in the shoulder-neck region. For the office workers, 27% of the variance in shoulder-neck symptoms was explained by the variance in the parameters "previous pain symptoms" and "psychosocial problems" in a multilinear regression model. In three groups of workers with different physical loads on the shoulder muscles the symptom scores for workers without previous pain symptoms and psychosocial problems were related to the physical load. For workers with previous pain symptoms and psychosocial problems, the symptom scores were high and similar for all three groups.

Is there a typical conflict in gastric complaints? An epidemiologic-psychoanalytic contribution to the question of conflict specificity in psychosomatic medicine

The question of conflict specificity for subjects with gastric complaints was investigated in the context of a representative, epidemiologic-psychoanalytic field study. Out of a population of 600 adults probands with dyspepsia were compared with individuals with musculoskeletal symptoms and 'healthy' subjects. Using interview protocols 2 'blinded' raters judged whether a dependency-independency conflict was present in different aspects of life. Findings supported the higher prevalence of the conflict among subjects with dyspepsia. Therefore, the conflict was considered typical, but not specific for the experimental group.

Trapezius muscle load as a risk indicator for occupational shoulder-neck complaints

Upper trapezius muscle activity was quantified by electromyographic (EMG) recordings using surface electrodes to study occupational muscle load as a risk indicator for the development of shoulder-neck complaints. Thirty-nine female production workers and thirty-two female office workers showed much larger interindividual differences than the mean difference in muscle activity between the two groups. By comparison with the production workers, the muscle activity patterns of the office workers were characterized by more short pauses and a lower static load. The median load level was similar for the two groups. For the office workers, but not for the production workers, weak correlations were found between symptoms of pain in the shoulder-neck region and some of the EMG parameters (static level and frequency of micropauses > 0.6 s. Current techniques for measuring shoulder muscle load by EMG recordings seem inadequate as screening methods to predict future risk of development of muscle pain symptoms.

Physical disability among Canadians reporting musculoskeletal diseases

About one million Canadian adults are estimated to have physical disabilities attributed to a musculoskeletal condition, a prevalence of 50.1/1,000 adults (all rates expressed/1,000). The specific musculoskeletal disease rates were arthritis/rheumatism (27.2), back (16.2), "other" (4.6), trauma (3.6) and bone (0.6). More women reported disabling musculoskeletal disease (61.0 versus 38.6, respectively). Prevalence rates increased with age from 6.2 among Canadians aged 15-24 years, to 264.7 aged 85 years and over. Limitations of mobility were more common than those of agility. Adults in institutions reported more disabilities than did adults in households (means 7.7 and 4.4, respectively).

Individual and work related factors associated with symptoms of musculoskeletal complaints. II. Different risk factors among sewing machine operators

Individual and work related risk factors in the development of occupational musculoskeletal complaints were studied in a group of 210 female production workers, mainly sewing machine operators. Another group of 35 female employees performing secretarial or laboratory duties were also included. The production workers had significantly higher symptom scores with respect to self reported musculoskeletal complaints than the group with more varied work tasks for the head, neck, shoulders, and arms, but not for the low back, hips, and the lower extremities. No significant differences were found in symptom level between geographically separate groups of production workers with similar work tasks. The main individual risk factor identified in this study was the experience of previous, similar symptoms in the same body region, but this factor only accounted for 2-3% of total variance in symptom score for the neck and shoulders. Other individual factors of importance for symptoms in the neck and shoulders were "signs of psychological problems" and "tendency of muscle tension," but these only account for about 1% of total variance in symptom score. Symptoms in the head and low back showed complex relations with individual parameters.

Psychosomatic musculoskeletal pain in childhood: clinical and psychological analyses of 100 children

The clinical and psychological findings on 100 children with psychosomatic musculoskeletal pain seen at a major pediatric rheumatology referral center are reported. Most (76%) were female, median age was 13 years, and median duration of symptoms was 1 year. Multiple painful sites were common (66%). The pain was constant (63%) or intermittent (37%); 45% had hyperesthesia, and almost all maintained a cheerful affect when complaining of severe pain. Two predominant abnormal family milieu were seen. One was cohesive, stable, and organized, but intolerant of separation and individuation. The other was chaotic, emotionally unsupportive, with high levels of conflict. Members of the cohesive family type reported significantly less distress than members of chaotic families. Enmeshment between mother and child was common in both family types. Although frequently viewed as bright, most of these children had normal intelligence, and some had unrecognized academic difficulty. These children, compared with those with arthritis, had a significantly lower global well-being score. Clinical depression was unusual (11%). Most (97%) responded favorably to intensive physical and occupational therapy along with individual or family psychotherapy; 78% become symptom free or fully functional. Children with these signs and symptoms should have full psychological evaluations and respond well to treatment directed toward decreasing pain and restoring function.

An Inventory of Positive Psychological Attitudes with potential relevance to health outcomes: validation and preliminary testing

This article describes the validation of an Inventory of Positive Psychological Attitudes that has potential relevance to health outcomes and its preliminary testing with chronic pain patients. The inventory taps two attitudinal domains: (1) life purpose and satisfaction and (2) self-confidence during potentially stressful situations. It also provides a total score. The inventory scales, developed using factor analysis, were found to have a strong degree of internal reliability and concurrent validity. Preliminary testing suggested that positive change on these scales correlates with positive changes in the health status of chronic pain patients. Multiple regression analyses suggested that the interactions of these positive psychological attitudes with health status are not fully accounted for by the interactions of negative psychological attitudes with health status.