Catarina Nordander

Disorders of the neck and upper limbs in women in the fish processing industry

OBJECTIVE--The aim was to study the association between personal factors and physical and psychosocial work environment factors and disorders of the neck or upper limbs among women in the fish processing industry. METHODS--A cross sectional study was performed on 206 women in the fish processing industry and 208 control women. Several physical and psychosocial work environment factors were evaluated. Subjective complaints about the neck or upper limbs were assessed by questionnaire and by a clinical examination. RESULTS--The study showed a high prevalence (35%) of diagnoses in the neck or shoulders of the exposed women. All prevalence odds ratios (PORs) were substantially higher in young women. There was a pronounced dose-response relation between disorders of the neck or shoulders and duration of employment for women < 45 years old. When studying 322 former workers, the proportion who claimed musculoskeletal complaints as the reason for leaving was highest among the older women. Muscular tension, stress or worry, work strain, and the largest fraction of the work time spent with highly repetitive work tasks were clearly associated with disorders of the neck or shoulders. The measurements of the wrist movements also showed that the work was performed almost without any pauses and that the median flexion and extension velocity was high (41 degree/s). The results of observation showed good agreement with the measurements of wrist motion. CONCLUSION--Work in the fish processing industry is a risk factor for disorders of the neck and upper limbs. Due to the homogenity of the physical work load in the exposed group, we could not show any associations between the objective measurements and disorders. In cross sectional studies the risk may be underestimated due to a healthy worker effect.

Influence of the subcutaneous fat layer, as measured by ultrasound, skinfold calipers and BMI, on the EMG amplitude

Surface electromyography (sEMG) is an important tool to estimate muscular activity at work. There is, however, a great inter-individual variation, even in carefully standardized work tasks. The sEMG signal is attenuated in the subcutaneous tissues, differently for each subject, which requires normalization. This is commonly made in relation to a reference contraction, which by itself, however, introduces a variance. A normalization method that is independent of individual motivation, motor control and pain inhibition would be desirable. The aim of the study was to explore the influence of the subcutaneous tissue thickness on sEMG amplitude. Ultrasound measurements of the muscle to skin surface distance were made bilaterally over the trapezius muscle in 12 females. Skinfold caliper measurements from these sites, as well as from four other sites, were made, body mass index (BMI) was recorded, and sEMG was recorded at maximal and submaximal contractions. The muscle–electrode distance, as measured by ultrasound, explained 33% and 31% (on the dominant and non-dominant sides respectively) of the variance of the sEMG activity at a standardized submaximal contraction (average between the sides, 46%); for maximal contractions the explained variance was 21%. Trapezius skinfold measurements showed poor correlations with sEMG. Instead, the mean of skinfold measurements from other sites explained as much as 68% (submaximal contraction). The corresponding figure for BMI was 67%. In conclusion, skinfold thickness explains a major part of the inter-individual variance in sEMG amplitude, and normalization to this measure is a possibility worth further evaluation.

Sensitivity of trapezius electromyography to differences between work tasks — influence of gap definition and normalisation methods

Surface electromyography (EMG) has been used extensively to estimate muscular load in studies of work related musculoskeletal disorders, especially for the trapezius muscle. The occurrences of periods of EMG silence (gaps), the time below a predetermined threshold level (muscular rest) and various percentiles of the amplitude distribution (APDF) are commonly used summary measures. However, the effects of the criteria used to calculate these measures (e.g., gap duration, threshold level, normalisation method) on the sensitivity of these measures to accurately differentiate work loads is not well known. Bilateral trapezius EMG was recorded, for a full workday, for 58 subjects following both maximal (MVE) and submaximal (RVE) reference contractions. Gap frequency, muscular rest, and percentiles were derived for eight fundamental work tasks. The calculations were performed using different gap duration criteria, threshold levels and normalisation methods.A gap duration of less than 1/2 s, and threshold level approximately 0.3% MVE for gap frequency, and approximately 0.5% MVE for muscular rest, were the criteria that optimised sensitivity to task differences. Minimal sensitivity to tasks and a high sensitivity to individuals was obtained using gap frequency with a threshold level of approximately 1% MVE. Normalisation to RVE, rather than MVE, improved sensitivity to differences between tasks, and reduced undesirable variability. Muscular rest was more sensitive to task differences than APDF percentiles.

Fish processing work: the impact of two sex dependent exposure profiles on musculoskeletal health

OBJECTIVES: To evaluate the impact of work tasks, physical exposure, and psychosocial factors on the risk of musculoskeletal disorders in men and women, in a defined industrial setting. METHODS: 116 male and 206 female fish industry workers were compared with 129 men and 208 women with more varied work. Physical and psychosocial work load as well as musculoskeletal complaints were recorded by a questionnaire. A physical examination was performed and an observation method was used for work evaluation. 196 male and 322 female former fish processing workers received a postal questionnaire. RESULTS: The women workers in the fish industry had worse working conditions than the men for repetitiveness, constrained neck postures, and psychosocial work environment. They also had higher prevalences of complaints of the neck and shoulder (prevalence odds ratio (POR) 1.9; 95% confidence interval (95% CI) 1.1 to 3.2), neck and shoulder and elbow and hand complaints (POR 2.9; 95% CI 1.8 to 4.7 and POR 2.8; 95% CI 1.6 to 4.7, respectively). The women more often than the men left the industry because of neck and upper limb complaints. Also, women in other work had a higher prevalence of complaints of the neck and shoulder (POR 2.3; 95% CI 1.1 to 5.1) than the men. The men in the fish processing industry had a higher prevalence of complaints of the neck and shoulder than the men in other work (POR 3.6; 95% CI 1.6 to 8.0). This difference was not shown up by the questionnaire. CONCLUSIONS: Despite superficially similar work, there were clear sex differences in physical exposure and psychosocial work environment. Work in the fish processing industry was associated with a high risk of neck and upper limb disorders in women, which was probably mainly due to their extremely repetitive work tasks; the corresponding men had less repetitive work and less disorders. Also, a healthy worker effect on neck and upper limb disorders was found. The advantage of a physical examination compared with a questionnaire is clearly shown.

Muscular rest and gap frequency as EMG measures of physical exposure : the impact of work tasks and individual related factors

Owing to an orderly recruitment of motor units, low threshold type I fibres are presumed to be vulnerable in contractions of long duration. To study load on these fibres muscular rest was registered as the time fraction of electromyographic (EMG) activity below a threshold. Moreover, the frequency of periods with muscular rest, EMG gaps, was derived, since a low gap frequency has been shown to be a risk factor for musculoskeletal disorders. Trapezius EMG was registered in 24 female hospital cleaners, 21 female office workers and 13 male office workers during one working day. Cleaners have a high risk of neck/shoulder pain and had much less muscular rest than office workers measured as a percentage of total registered time (median value= 1.5%, range= 0.2-13% vs. median value= 12%, range= 0.0-32%, respectively). Gap frequency showed no difference between the two occupational groups. Both measures displayed a wide inter-individual variation. For the cleaners, some of the variance was explained by body mass index (BMI) and age, with lower values of muscular rest for older subjects with a high BMI. Among the office workers, low values of muscular rest and a high gap frequency were registered in subjects with a low subjective muscular tension tendency. Gender, strength, smoking, job strain, employment time and musculoskeletal symptoms had no impact on either EMG measure.

Risk of musculoskeletal disorders among females and males in repetitive/constrained work

This paper combines epidemiological data on musculoskeletal morbidity in 40 female and 15 male occupational groups (questionnaire data 3720 females, 1241 males, physical examination data 1762 females, 915 males) in order to calculate risk for neck and upper limb disorders in repetitive/constrained vs. varied/mobile work and further to compare prevalence among office, industrial and non-office/non-industrial settings, as well as among jobs within these. Further, the paper aims to compare the risk of musculoskeletal disorders from repetitive/constrained work between females and males. Prevalence ratios (PR) for repetitive/constrained vs. varied/mobile work were in neck/shoulders: 12-month complaints females 1.2, males 1.1, diagnoses at the physical examination 2.3 and 2.3. In elbows/hands PRs for complaints were 1.7 and 1.6, for diagnoses 3.0 and 3.4. Tension neck syndrome, cervicalgia, shoulder tendonitis, acromioclavicular syndrome, medial epicondylitis and carpal tunnel syndrome showed PRs > 2. In neck/shoulders PRs were similar across office, industrial and non-office/non-industrial settings, in elbows/hands, especially among males, somewhat higher in industrial work. There was a heterogeneity within the different settings (estimated by bootstrapping), indicating higher PRs for some groups. As in most studies, musculoskeletal disorders were more prevalent among females than among males. Interestingly, though, the PRs for repetitive/constrained work vs. varied/mobile were for most measures approximately the same for both genders. In conclusion, repetitive/constrained work showed elevated risks when compared to varied/mobile work in all settings. Females and males showed similar risk elevations. This article enables comparison of risk of musculoskeletal disorders among many different occupations in industrial, office and other settings, when using standardised case definitions. It confirms that repetitive/constrained work is harmful not only in industrial but also in office and non-office/non-industrial settings. The reported data can be used for comparison with future studies.

Validity of self-assessed reports of occurrence and duration of occupational tasks.

To obtain quantitative estimates of the physical workload in epidemiological and intervention studies of musculoskeletal disorders, there is a need to extend task based exposure data to job exposure profiles. For this purpose a work task diary was developed and evaluated. This was validated against direct observations of a days work for twenty-two female office workers and twenty female hospital cleaners. There was a good agreement regarding the occurrence of the main tasks. However, the less time-consuming tasks were under-reported. Moreover, about two thirds of the changes between tasks were not reported. The difficulties of defining tasks that function as occupational entities seems to be a major reason for the lack of agreement. The underestimation of the duration of breaks/pauses was most pronounced for the cleaners. Still, the diary would be useful for the calculation of job exposure, by time-weighting task exposure data, when the tasks and/or their duration vary between days.

Population-based consultation patterns in patients with shoulder pain diagnoses.

BackgroundTo assess the annual consultation prevalence and new onset consultation rate for doctor-diagnosed shoulder pain conditions.MethodsWe identified all residents in the southernmost county in Sweden who received a shoulder pain diagnosis during 2006 (ICD-10 code M75). In subjects who did not consult due to such disorders during 2004 and 2005, we estimated the new onset consultation rate. The distribution of specific shoulder conditions and the length of the period of repeated consultation were calculated.ResultsAnnual consultation prevalence was 103/10 000 women and 98/10 000 men. New onset consultation rate was 80/10 000 women (peak in age 50–59 at 129/10 000) and 74/10 000 men (peak in age 60–69 at 116/10 000). About one fifth of both genders continued to consult more than three months after initial presentation, but only a few percent beyond two years. Rotator cuff - and impingement syndromes were the most frequent diagnoses.ConclusionThe annual consultation prevalence for shoulder pain conditions (1%) was similar in women and men, and about two thirds of patients consulted a doctor only once. Impingement and rotator cuff syndromes were the most frequent diagnoses.

Physiological and psychological reactions to work in men and women with identical job tasks

Differences in physiological functioning in the hypothalamus–pituitary–adrenal cortex axis and the autonomic nervous system have been suggested to contribute to many of the health differences that may be observed between men and women as well as being relevant for the development of musculoskeletal pain. To clarify whether men and women with identical work tasks reacted differently when doing work known to induce musculoskeletal pain, ratings and physiological measurements were obtained at work start (15:30) and at the end of the workshift (22:30) on 17 men and 20 women. Men showed a larger decrease in perceived energy levels during the workshift but there were no differences between men and women as regards cortisol, adrenaline, noradrenaline, heart-rate activation, perceived stress, pain and physical exertion. In conclusion, differential physiological activation during the workshift seem to be an unlikely mechanism for explaining gender differences in pain associated with exposure to awkward and repetitive movements.

Cross-sectional associations between occupational factors and musculoskeletal pain in women teachers, nurses and sonographers

BackgroundIt is usually assumed that musculoskeletal pain is associated with both the physical workload and the psychosocial work environment, as well as with personal and lifestyle factors. This study aims to ascertain the prevalence of musculoskeletal pain in women with varying or different occupational exposures, and to explore the associations between musculoskeletal pain and the occupational and personal factors.MethodsA questionnaire on physical, psychosocial and individual factors was answered by 1591 women in five occupational groups with contrasting occupational exposures (teachers, anaesthetic, theatre, and assistant nurses, and sonographers). The outcome measure was musculoskeletal pain (in a new model based on frequency and intensity of complaints the preceding year) from the neck, shoulders, hands, lower back and feet.ResultsNeck pain was equally frequent among teachers, assistant nurses and sonographers, and less frequent in anaesthetic and theatre nurses. The sonographers experienced the highest prevalence of shoulder pain, while the assistant nurses were the most affected in the wrists and hands, lower back, and feet.The teachers reported the highest scores in most of the psychosocial dimensions. The theatre nurses scored highest in strenuous work postures and movements (mechanical exposure index, MEI), and the assistant nurses in physical activity and lifting (physical exposure index, PHYI). Multivariable models in the total population showed that both the physical workload and the psychosocial work environment were associated with pain in all body regions, though different factors affected different regions. Pain in the neck, shoulders, hands and lower back was strongly associated with a high MEI and high job demands, while pain in the feet was associated with a high PHYI and a high BMI. A young age was associated with pain in the neck, and an older age was associated with pain in the hands and feet. Lack of time for personal recovery was associated with pain in the shoulders and lower back.ConclusionsThe occupational groups were affected differently and need different protective measures. For the teachers, the psychosocial work environment should be improved. The surgical staff and sonographers require measures to mitigate lifting and constrained postures.