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.     

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 effect of a resistance-training program on muscle strength, physical workload, muscle fatigue and musculoskeletal discomfort: An experiment

The aim of the study was to investigate the effectiveness of a resistance-training program on muscle strength of the back and neck/shoulder muscles, relative physical workload, muscle fatigue and musculoskeletal discomfort during a simulated assembly and lifting task. Twenty-two workers were randomized over an 8-week resistance-training group, and a control group. Isokinetic muscle strength was assessed using the Cybex dynamometer, muscle fatigue was measured using EMG, and perceived discomfort was measured using a 10-point scale. At the follow-up, we found no effect of the resistance-training program on isokinetic muscle strength of the back and shoulder muscles. Furthermore, we did not find any effect on EMG data, nor on musculoskeletal discomfort during the simulated work tasks. However, trained workers performed the lifting tasks for a longer time before reporting considerable discomfort than those in the control group.     

Strength,endurance and fatigue response of rotator cuff muscles during isometric exertions

Among the shoulder musculoskeletal disorders (MSDs), rotator cuff disorders are prevalent and known to substantially limit an individual's strength and ability to work. Despite the frequency and cost of rotator cuff injuries, very little research has been done on understanding the load response relationship of rotator cuff muscles. Therefore, this study was aimed at evaluating the strength, endurance and fatigue response of rotator cuff muscles. As a first step, strengths of Supraspinatus, Infraspinatus, and Teres Minor were measured for ten healthy male participants using muscle specific Maximum Voluntary Contractions (MVC). Then, endurance time and surface Electromyography (EMG) data were recorded during 15%, 30%, 45%, and 60% MVC exertions. Infraspinatus exhibited the highest strength followed by Teres Minor and Supraspinatus. Despite the strength differences, small variations were observed in the endurance time between the muscles. The effect of %MVC exertions on endurance time, average muscle activity and muscle fatigue were statistically significant. Median frequency decreased and muscle activation increased with an increase in force exertion levels; however, the changes observed for an increase in the exertion level from 15% to 30% MVC were much higher than the changes observed for an increase in the exertion level from 45% to 60% MVC.Relevance to industryResults of this study indicate that the rotator cuff muscles have different strengths but exhibit very similar endurance and fatigue behavior. These findings can assist ergonomic practitioners with the design and/or evaluation of workplace upper extremity exertions to reduce/manage stress on the rotator cuff muscles and shoulder.     

Workload and musculoskeletal problems: a comparison between welders and office clerks (with reference also to fishermen)

Previous studies have shown that subjective as well as clinical shoulder signs and symptoms are more common among welders than among office clerks. In the present study we wished to further evaluate the influence of different jobs on musculoskeletal problems, as well as the relationship between objective signs and subjective symptoms. This study confirmed that symptoms and signs from the shoulder were more common among the welders, who also had more subjective symptoms and clinical signs from other parts of the musculoskeletal system, Range of motion in different joint systems was, however, similar in the two groups except in external rotation of the shoulder, where welders had a more limited range. The degree of co-existence of subjective symptoms and clinical signs differed between different parts of the musculoskeletal system and was low particularly in the low back, hips, and ankles. This indicates low validity of many common clinical methods for determining musculoskeletal dysfunciion. General health was good in both vocational groups and isometric strength for the welders was intermediate between that of office clerks (who had lower strength) and that of fishermen (who had higher strength, as disclosed in a previous investigation). To a similar degree welders and fishermen also had objective signs from most parts of the musculoskeletal system, whereas subjective symptoms from some parts of the body and medical consultations due to these problems were more common among welders. Atrophied shoulder muscles were more common among welders than among fishermen, whereas crepitations in the shoulder tended to be more common among the fishermen. This indicates that heavy dynamic work and prolonged static work may both induce shoulder injuries, but of different types.     

Workload and musculoskeletal problems: a comparison between welders and office clerks (with reference also to fishermen).

Previous studies have shown that subjective as well as clinical shoulder signs and symptoms are more common among welders than among office clerks. In the present study we wished to further evaluate the influence of different jobs on musculoskeletal problems, as well as the relationship between objective signs and subjective symptoms. This study confirmed that symptoms and signs from the shoulder were more common among the welders, who also had more subjective symptoms and clinical signs from other parts of the musculoskeletal system. Range of motion in different joint systems was, however, similar in the two groups except in external rotation of the shoulder, where welders had a more limited range. The degree of co-existence of subjective symptoms and clinical signs differed between different parts of the musculoskeletal system and was low particularly in the low back, hips, and ankles. This indicates low validity of many common clinical methods for determining musculoskeletal dysfunction. General health was good in both vocational groups and isometric strength for the welders was intermediate between that of office clerks (who had lower strength) and that of fishermen (who had higher strength, as disclosed in a previous investigation). To a similar degree welders and fishermen also had objective signs from most parts of the musculoskeletal system, whereas subjective symptoms from some parts of the body and medical consultations due to these problems were more common among welders. Atrophied shoulder muscles were more common among welders than among fishermen, whereas crepitations in the shoulder tended to be more common among the fishermen. This indicates that heavy dynamic work and prolonged static work may both induce shoulder injuries, but of different types.     

Incidence of self-reported reduced productivity owing to musculoskeletal symptoms: association with workplace and individual factors among computer users

The aim of the present study was to assess the incidence and identify possible risk factors for self-reported reduced productivity owing to musculoskeletal symptoms among computer users. DESIGN: a cohort study with a baseline questionnaire and monthly follow ups during 10 months. METHODS: the study base consisted of 1,283 computer users, 636 men and 896 women. Ergonomists observed workstation characteristics before entering the cohort. Cases were defined as subjects reporting reduced productivity or reporting being on sick leave owing to musculoskeletal symptoms. RESULTS: women had approximately two times the incidence of self-reported reduced productivity owing to symptoms in the neck, shoulder and in the forearm/hand than men. There was no difference in gender for the incidence of self-reported reduced productivity owing to back symptoms. Working overtime and job demands were risk factors for self-reported reduced productivity owing to neck and back symptoms. Physical exercise fewer than 8 times the last month was a risk factor for self-reported reduced productivity owing to neck, shoulder and forearm/hand symptoms. Computer mouse use for more than 0.5 h/day was a risk factor for self-reported reduced productivity owing to shoulder and forearm/hand symptoms. CONCLUSIONS: risk factors for self-reported reduced productivity owing to musculoskeletal symptoms included life style factors, such as overweight and low physical exercise, occupational factors, such as overtime, job demands and computer mouse operating time.     

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.     

Musculoskeletal pain among teleworkers: Frequency and associated factors

Teleworking, also known as remote working, has become the new norm for many workers since the coronavirus disease 2019 (COVID-19) pandemic. Studies show that during this time, the incidence of musculoskeletal pain is increasing among these workers. Despite this, few studies have addressed the possible correlates of musculoskeletal paśin in teleworkers, with several potential predictors receiving little or no attention in published studies. With this in mind, an online survey was conducted among organizations in the IT and communications sectors in Malta. Information was collected from 459 teleworkers on the frequency of telework, frequency of work during nonworking hours, exercise frequency, burnout, and ergonomic arrangements. Demographic data were also collected. Results revealed that 55.8% reported one or more musculoskeletal pain. Back pain was the most common, followed by neck and shoulder pain. The presence of pain, the number of painful body areas, and the presence of back, neck, and shoulder pain were each individually associated with work during nonworking hours, lower levels of exercise, and higher levels of burnout. It is argued that musculoskeletal pain appears to be common among teleworkers and may negatively impact the quality of life and organizational performance. Companies and occupational health practitioners should strive to identify the prevalence of these problems among their teleworkers, develop appropriate preventive measures, and support workers to obtain multidisciplinary care when needed.     

Perceived musculoskeletal symptoms among dental students in the clinic work environment

Musculoskeletal symptoms are a major concern among dental practitioners. Dental students perform the same clinical tasks as dentists in private practice, yet only recently has scientific evidence suggested a relationship between the tasks and musculoskeletal symptoms. This study investigates the clinical tasks that place students at physical risk and the relationship between the tasks and musculoskeletal symptoms. Student perceptions of physical symptoms were established with a questionnaire identifying variables on general health, tasks, physical demands, workload and environment. A total of 61% (358/590) reported that during the past year they experienced musculoskeletal symptoms related to work at dental school (second year (n = 212), third year (n = 201) and fourth year (n = 177)). Of those students, the neck represented 48%, shoulder 31%, back 44% and hands 20% (p < 0.001). Third year students reported the highest occurrence of symptoms in every body area (p < 0.001). Third and fourth year students reported significant relationships between the occurrence of symptoms and equipment utilisation, work efficiency and general health. Further studies are recommended to evaluate types and levels of potential risk factors. A total of 75% of dental practitioners are at risk for developing work-related musculoskeletal disorders. Results from this study have found that dental students were no exception. Third year dental students reported the highest level of musculoskeletal symptoms with the prevalence of pain in the neck, shoulder and lower back.     

Does musculoskeletal discomfort at work predict future musculoskeletal pain?

The objective of this prospective cohort study was to evaluate if peak or cumulative musculoskeletal discomfort may predict future low-back, neck or shoulder pain among symptom-free workers. At baseline, discomfort per body region was rated on a 10-point scale six times during a working day. Questionnaires on pain were sent out three times during follow-up. Peak discomfort was defined as a discomfort level of 2 at least once during a day; cumulative discomfort was defined as the sum of discomfort during the day. Reference workers reported a rating of zero at each measurement. Peak discomfort was a predictor of low-back pain (relative risk (RR) 1.79), neck pain (RR 2.56), right or left shoulder pain (RR 1.91 and 1.90). Cumulative discomfort predicted neck pain (RR 2.35), right or left shoulder pain (RR 2.45 and 1.64). These results suggest that both peak and cumulative discomfort could predict future musculoskeletal pain.     

Modeling the influence of individual and employment factors on musculoskeletal disorders in fabrication industry

This study was designed to identify the individual and employment factors that influence highly frequent, less severe self‐reported musculoskeletal disorder pain incidences among welders. A self‐reporting questionnaire to measure two individual factors (age and experience), six employment factors (physical workload, working hours, shift work, nature of employment, mode of apprenticeship training, and association with present employer), along with a modified Nordic questionnaire response sheet was used to collect data. The survey was conducted among welders employed in a fabrication cluster in a southern part of India. A total of 987 completed questionnaires (response rate: 66%) were analyzed using the SPSS program. The analysis showed that two employment factors, “shift work” and “mode of apprenticeship training” significantly influence self‐reported musculoskeletal disorder pain. The mode of apprenticeship training was found to influence musculoskeletal disorder pain in the neck region for annual prevalence and causes annual disability in neck and upper back regions. Similarly, shift work was found to influence musculoskeletal disorder pain in the shoulder and neck regions for weekly and annual prevalence and causes annual disability in shoulder, wrist/hands, upper back, and hip/thigh/buttock regions among welders. These factors can be considered as points for targeting intervention efforts.     

Perceived musculoskeletal symptoms among dental students in the clinic work environment

Musculoskeletal symptoms are a major concern among dental practitioners. Dental students perform the same clinical tasks as dentists in private practice, yet only recently has scientific evidence suggested a relationship between the tasks and musculoskeletal symptoms. This study investigates the clinical tasks that place students at physical risk and the relationship between the tasks and musculoskeletal symptoms. Student perceptions of physical symptoms were established with a questionnaire identifying variables on general health, tasks, physical demands, workload and environment. A total of 61% (358/590) reported that during the past year they experienced musculoskeletal symptoms related to work at dental school (second year (n = 212), third year (n = 201) and fourth year (n = 177)). Of those students, the neck represented 48%, shoulder 31%, back 44% and hands 20% (p < 0.001). Third year students reported the highest occurrence of symptoms in every body area (p < 0.001). Third and fourth year students reported significant relationships between the occurrence of symptoms and equipment utilisation, work efficiency and general health. Further studies are recommended to evaluate types and levels of potential risk factors. A total of 75% of dental practitioners are at risk for developing work-related musculoskeletal disorders. Results from this study have found that dental students were no exception. Third year dental students reported the highest level of musculoskeletal symptoms with the prevalence of pain in the neck, shoulder and lower back.     

Neck and shoulder muscle activity among ophthalmologists during routine clinical examinations

Muscular demands during common clinical ophthalmologic activities may contribute to the high prevalence of musculoskeletal health outcomes observed among ophthalmologists and other eye care physicians. Characterizations of the muscle activation patterns in the live ophthalmologic environment are lacking. This study was conducted to (i) characterize the frequencies and durations of common activities performed by ophthalmologists during routine clinical examinations, (ii) characterize neck and shoulder muscle activation patterns during the whole clinical work day, and (iii) explore differences in neck and shoulder muscle activation patterns between common clinical activities. Fifteen ophthalmologists performed routine patient examinations in an outpatient ophthalmology clinic while continuous surface electromyography measurements of the upper trapezius and anterior deltoid muscles were obtained. Results indicated that while computer use was the most frequently performed clinical activity, use of the indirect ophthalmoscope, followed by use of the slit lamp biomicroscope, required greater muscular demands than computer use or other clinical activities. Results provide evidence that the clinical activities of indirect ophthalmoscope and slit lamp biomicroscope use are appropriate for ergonomic intervention.     

This month ‘Technik ist alles’

The objective of this prospective cohort study was to evaluate if peak or cumulative musculoskeletal discomfort may predict future low-back, neck or shoulder pain among symptom-free workers. At baseline, discomfort per body region was rated on a 10-point scale six times during a working day. Questionnaires on pain were sent out three times during follow-up. Peak discomfort was defined as a discomfort level of 2 at least once during a day; cumulative discomfort was defined as the sum of discomfort during the day. Reference workers reported a rating of zero at each measurement. Peak discomfort was a predictor of low-back pain (relative risk (RR) 1.79), neck pain (RR 2.56), right or left shoulder pain (RR 1.91 and 1.90). Cumulative discomfort predicted neck pain (RR 2.35), right or left shoulder pain (RR 2.45 and 1.64). These results suggest that both peak and cumulative discomfort could predict future musculoskeletal pain.     

Gender differences in prevalence of upper extremity musculoskeletal disorders

A literature review was conducted on the current literature base to determine the strength of support for the hypothesis that women experience higher prevalences of upper extremity musculoskeletal disorders (UEMSDs) than men. Fifty-six articles were reviewed for data on gender differences in frequency, incidence or prevalence rates for musculoskeletal disorders specific to the upper extremities. These articles included both general and working populations. The majority of the studies showed that women had significantly higher incidences of various types of UEMSDs than men. This trend was consistently observed in studies based on self-report or plant/workers compensation records, with and without physical examination, and after adjusting for potential confounders such as age and physical work factors. With men as the referent, the odds ratio (OR) or prevalence ratio (PR) for UEMSDs ranged from 0.85 to 10.05 for self report. For self report combined with physical examination, the OR/PR ranged from 0.66 to 11.4. The OR/PR for carpal tunnel syndrome (CTS) ranged from 0.6 to 2.87 with confounder adjustment. These findings suggest that women do have significantly higher prevalences than men for many types of UEMSDs, even after controlling for the type of data source and confounders such as age or work factors.     

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.     

Gender differences in prevalence of upper extremity musculoskeletal disorders

A literature review was conducted on the current literature base to determine the strength of support for the hypothesis that women experience higher prevalences of upper extremity musculoskeletal disorders (UEMSDs) than men. Fifty-six articles were reviewed for data on gender differences in frequency, incidence or prevalence rates for musculoskeletal disorders specific to the upper extremities. These articles included both general and working populations. The majority of the studies showed that women had significantly higher incidences of various types of UEMSDs than men. This trend was consistently observed in studies based on self-report or plant/workers compensation records, with and without physical examination, and after adjusting for potential confounders such as age and physical work factors. With men as the referent, the odds ratio (OR) or prevalence ratio (PR) for UEMSDs ranged from 0.85 to 10.05 for self report. For self report combined with physical examination, the OR/PR ranged from 0.66 to 11.4. The OR/PR for carpal tunnel syndrome (CTS) ranged from 0.6 to 2.87 with confounder adjustment. These findings suggest that women do have significantly higher prevalences than men for many types of UEMSDs, even after controlling for the type of data source and confounders such as age or work factors.     

Towards exposure limits for working postures and musculoskeletal symptoms – a prospective cohort study

Occupational postures are considered to be an important group of risk factors for musculoskeletal pain. However, the exposure-outcome association is not clear yet. Therefore, we aimed to determine the exposure-outcome association of working postures and musculoskeletal symptoms. Also, we aimed to establish exposure limits for working postures. In a prospective cohort study among 789 workers, intensity, frequency and duration of postures were assessed at baseline using observations. Musculoskeletal pain was assessed cross-sectionally and longitudinally and associations of postures and pain were addressed using logistic regression analyses. Cut-off points were estimated based on ROC-curve analyses. Associations were found for kneeling/crouching and low-back pain, neck flexion and rotation and neck pain, trunk flexion and low-back pain, and arm elevation and neck and shoulder pain. The results provide insight into exposure-outcome relations between working postures and musculoskeletal symptoms as well as evidence-based working posture exposure limits that can be used in future guidelines and risk assessment tools.

Practitioner Summary: Our study gives insight into exposure-outcome associations of working postures and musculoskeletal symptoms (kneeling/crouching and low-back pain, neck flexion/rotation and neck pain, trunk flexion and low-back pain, and arm elevation and neck and shoulder pain). Results furthermore deliver evidence-based postural exposure limits that can be used in guidelines and risk assessments.     

Development and initial assessment of objective fatigue measures for apple harvest work

Previous research has shown that neck, back and shoulder musculoskeletal strain is a major occupational health problem affecting migrant orchard harvest workers. Researchers seek to measure the effect of an ergonomic modification to the apple picking bucket on muscle fatigue, however objective measures for use in the orchard are not yet available.

The purpose of this study is to develop simple back, shoulder or arm strength measures, which detect statistically significant drops in strength over one workday. Candidate muscle strength measures were piloted in the laboratory, adapted for the orchard and evaluated (n=102). Data were analyzed for morning to afternoon fatigue, and for correlation between fatigue score and hours worked.

In the laboratory, the timed arm hold (35.7% time reduction, 95% CI: 21.81–49.61), and the timed spinal extension (31.8% time reduction, 95% CI: 23.54–39.96) showed significant fatigue. In the orchard (n=102), only the timed arm hold showed significant (11.4%, p<.0001) fatigue. The potential effect of field conditions and subject motivation on these results needs further exploration.