Physical limitations and musculoskeletal complaints associated with work in unusual or restricted postures: a literature review

A biomechanical evaluation of firefighters' musculoskeletal loads when carrying self-contained breathing apparatus in walking and running

INTRODUCTION

Musculoskeletal loading data are needed to design ergonomic intervention for firefighters. This study aimed to quantify the firefighters' musculoskeletal loads during self-contained breathing apparatus (SCBA) carriage and evaluate the effectiveness of shoulder strap length variation for the prevention of SCBA-related injuries.

METHOD

Twelve firefighters (height: 174.6 ± 2.4 cm, mass: 67 ± 3.5 kg, BMI = 22 ± 1 kg/m2) participated the walking and running protocols with no SCBA equipped and three varying-strapped SCBAs conditions. Joint range of motion and surface electromyography (sEMG) were synchronously measured. Subsequently, joint kinematics was inputted for subject-specific musculoskeletal modeling to estimate muscle forces and joint reaction forces, while the sEMG was used to validate the model. Repeated measures analysis of variance was used for the main effects (p < 0.05). Independent samples t-test was performed to determine differences between walking and running.

RESULTS

Walking with SCBA increased the rectus femoris force and hip reaction force by 34.92% [F = 53.629; p < 0.001; η2 = 0.317] and 34.71% [F = 53.653; p < 0.001; η2 = 0.517], the growth rate was 54.2% [F = 76.487; p < 0.001; η2 = 0.418] and 51.19% [F = 69.201; p < 0.001; η2 = 0.652] during running, respectively. Running with SCBA significantly increased the knee reaction force by 63.04% [F = 83.960; p < 0.001; η2 = 0.797], while only 18.49% increase during walking. Adjusting SCBA shoulder strap length significantly altered the rectus abdominis force and L4/L5 reaction force during walking and running.

CONCLUSIONS

Results revealed that rectus femoris activity, hip and knee exertion was sensitive to SCBA carriage. The variation of shoulder strap length has potential to influence the risk of low back pain (LBP).

PRACTICAL APPLICATIONS

The findings suggest that fire services promote targeting physical training at firefighters' hip and knee regions. Test firefighters in this study were not advisable to adjust their shoulder strap at loose-fitting condition. The compatibility design of the trunk morphology and SCBA back-mounted frame was suggested for the management of LBP.

The Correlation between Neck Pain and Disability, Forward Head Posture, and Hyperkyphosis with Opium Smoking: A Cross-Sectional Study from Iran

Opium smoking has been a common practice in Iran for many years, with people often smoking for long hours. During the COVID-19 pandemic, there was an increase in opium smoking due to false beliefs about its protective effects against COVID-19 infection. In this study, we aimed to examine the association between the non-ergonomic positions associated with traditional opium smoking in Iran and the development of neck pain and disability, forward head posture (FHP), and hyperkyphosis (HK). In this cross-sectional, correlational study, a total of 120 individuals who smoked opium were selected based on the inclusion criteria. They were interviewed about their addiction profile using the Lite version of the Addiction Severity Index and the Leeds Dependence Questionnaire. The presence of neck pain and disability was also evaluated using the Visual Analog Scale and the Neck Disability Index. The participants were examined for FHP via side-view photography and for HK using a flexible ruler. Data were analyzed using correlation coefficient tests and stepwise linear regression analysis. Based on the results, homelessness, the lifetime duration of opium smoking (in months), the duration of daily opium smoking (in minutes), and the severity of drug dependence had significant relationships with the severity of neck pain, neck disability, FHP, and HK. Homelessness was the strongest predictor of neck pain and disability (R2 = 0.367, p < 0.001), FHP (R2 = 0.457, p < 0.001), and HK (R2 = 0.476, p < 0.001), followed by the lifetime duration of opium smoking and the duration of daily opium smoking, respectively, in which R2 increased to 0.505 (p = 0.011), 0.546 (p = 0.022), and 0.570 (p = 0.004) with the addition of two other variables. Overall, an increase in the duration of sitting in non-ergonomic positions could lead to neck pain and disability, FHP, and HK due to the non-neutral posture of opium smokers.

A Cross-Sectional Descriptive Study of Musculoskeletal Disorders (MSDs) of Male Shipbuilding Workers and Factors Associated the Neck, Shoulder, Elbow, Low Back, or Knee MSDs

This study investigates the cross-sectional descriptive characteristics of male shipbuilding workers’ musculoskeletal disorders (MSDs) and factors associated with MSDs in the neck, shoulders, elbows, low back, or knees. From the national compensation data confirmed as MSDs during three years between 2015 and 2017, 985 male workers were analyzed in terms of age, work experience, occupations, company size, and MSD type according to each body region. In the analysis of frequency and severity according to ‘occupation–body region–MSD type’, ‘Electrician/plumber–low back–herniated disc’ (6.9%) was the form of MSDs with the highest frequency among total MSDs, and ‘Crane–neck–herniated disc’ (500.5 days) was the highest mean of sick leave days. The low back MSDs (28.9%) were the highest frequency, followed by shoulders (27.7%) and knees (16.2%). The herniated disc was frequent in the neck and lumbar region, and the mean of sick leave days of the neck herniated disc (402.2 days) was greater than that of the low back herniated disc (321.1 days). While a rupture was frequent in the shoulder or knee region, the mean of sick leave days for shoulder rupture (335.1 days) was greater than that of the knee rupture (318.8 days). In the binary logistic regression analysis, age was positively associated with MSDs in the neck, shoulder, or elbow regions, while the low back MSDs category was not positively associated with age. Large companies with >1000 employees were highly associated with neck MSDs, while small companies with <30 employees were related to the low back MSDs. This study derives the characteristics for frequency and sick leave days of MSDs in the neck, shoulders, elbows, low back, or knees to prioritize MSD prevention information. The results of this study can be used as primary data for establishing MSD prevention policy.

Quality and usability of clinical assessments of static standing and sitting posture: A systematic review

BACKGROUND

A validated method to assess sitting and standing posture in a clinical setting is needed to guide diagnosis, treatment and evaluation of these postures. At present, no systematic overview of assessment methods, their clinimetric properties, and usability is available.

OBJECTIVE

The objective of this study was to provide such an overview and to interpret the results for clinical practice.

METHODS

A systematic literature review was performed according to international guidelines. Two independent reviewers assessed risk of bias, clinimetric values of the assessment methods, and their usability. Quality of evidence and strength of recommendations were determined according to the Grading of Recommendations Assessment, Development and Evaluation working group (GRADE).

RESULTS

Out of 27,680 records, 41 eligible studies were included. Thirty-two assessment instruments were identified, clustered into five categories. The methodological quality of 27 (66%) of the articles was moderate to good. Reliability was most frequently studied. Little information was found about validity and none about responsiveness.

CONCLUSIONS

Based on a moderate level of evidence, a tentative recommendation can be made to use a direct visual observation method with global posture recorded by a trained observer applying a rating scale.

Physical work conditions and disparities in later life functioning: Potential pathways

Research in the US on the social determinants of reduced physical functioning at older ages has typically not considered physical work conditions as contributors to disparities. We briefly describe a model of occupational stratification and segregation, review and synthesize the occupational health literature, and outline the physiological pathways through which physical work exposures may be tied to long-term declines in physical functioning. The literature suggests that posture, force, vibration, and repetition are the primary occupational risk factors implicated in the development of musculoskeletal disorders, through either acute injuries or longer-term wear and tear. Personal risk factors and environmental and structural work characteristics can modify this association. In the long-term, these musculoskeletal disorders can become chronic and ultimately lead to functional limitations and disabilities that interfere with one's quality of life and ability to remain independent. We then use data on occupational characteristics from the Occupational Information Network (O*NET) linked to the 2019 American Community Survey (ACS) to examine disparities among sociodemographic groups in exposure to these risk factors. Occupations with high levels of these physical demands are not limited to those traditionally thought of as manual or blue-collar jobs and include many positions in the service sector. We document a steep education gradient with less educated workers experiencing far greater physical demands at work than more educated workers. There are pronounced racial and ethnic differences in these exposures with Hispanic, Black, and Native American workers experiencing higher risks than White and Asian workers. Occupations with high exposures to these physical risk factors provide lower compensation and are less likely to provide employer-sponsored health insurance, making it more difficult for workers to address injuries or conditions that arise from their jobs. In sum, we argue that physical work exposures are likely an important pathway through which disparities in physical functioning arise.

Developing and Evaluating a Mixed Sensor Smart Chair System for Real-Time Posture Classification: Combining Pressure and Distance Sensors

A novel sensor-embedded smart chair system was developed to monitor and classify a worker's sitting postures in real time. The smart chair system was a mixed sensor system utilizing six pressure sensors and six infrared reflective distance sensors in combination. The pressure sensors were embedded in the seat cushion to gather seat cushion pressure distribution data. The distance sensors were placed in the seatback to measure seatback-trunk distances at different locations in the frontal plane. The use of the seatback distance sensors represented a unique design feature, which distinguished the mixed sensor system from the previous posture monitoring systems. Employing a k-Nearest Neighbor algorithm, the mixed sensor system classified an instantaneous posture as one of posture categories determined based on an analysis of the ergonomics literature on sitting postures and sitting-related musculoskeletal problems. The mixed sensor system was evaluated in posture classification performance in comparison with two benchmark systems that utilized only a single type of sensors. The purpose of the comparisons was to determine the utility of the design combining seat cushion pressure sensors and seatback distance sensors. The mixed sensor system yielded significantly superior classification performance than the two benchmark systems. The mixed sensor system is low-cost utilizing only a small number of sensors; yet, it accomplishes accurate classification of postures relevant to the ergonomic analyses of seated work tasks. The mixed sensor system could be utilized for various applications including the development of a real-time posture feedback system for preventing sitting-related musculoskeletal disorders.

Effects of Line of Vision on Posture, Muscle Activity and Sitting Balance During Tooth Preparation

OBJECTIVES

Most dentists maintain awkward and restricted postures for prolonged periods that stress the body while providing direct patient care. Information about working posture must be analysed in a more systematic manner to provide a deeper understanding of the relationship between working posture and work-related musculoskeletal disorders (MSD). Therefore, the present study aimed to clarify the effects of different lines of vision during tooth preparation, such as the direct and the mirror view technique, on-body tilt (angle), muscle activity, and sitting balance, which may correlate with the reduction or prevention of MSD.

METHODS

A mannequin head with a maxillary right first molar embedded in a model was attached to the dental chair headrest. Two different techniques for tooth preparation were selected: direct view and mirror view. Muscle activity, body tilt (angle), and sitting balance were analysed as independent parameters.

RESULTS

Different tooth preparation techniques had a distinct influence on body tilt (angle), muscle activity, and sitting balance. The direct view technique resulted in significantly larger values for all parameters, except for the activity of the spinal column erector muscles than the mirror view technique.

CONCLUSION

Based on these results, the direct view technique for tooth preparation, which is used by most dentists in practice, imposes a burden on the lower back, shoulders, and neck of the dentist.

Pre-placement examinations for newly recruited health care support staff

Objective

While musculoskeletal disorders (MSD) and physical strength have been extensively studied in health care professionals, little attention has been paid to health care support staff, such as patient care assistants and operation patient assistants, whose jobs are physically demanding. The purpose of this paper was to examine the musculoskeletal symptoms and physical strength of newly recruited health care support staff.

Method

Convenience sampling was conducted on 111 newly employed health care support staff in a public hospital. A custom-made pre-placement examination was performed. Data were analysed using descriptive, correlation, and regression analyses.

Results

Nearly one-third (32%) of the newly recruited health care support staff had experienced musculoskeletal symptoms in at least one body part during the preceding 12 months. Two-thirds (68%) of subjects were physically inactive, and sixty percent was overweight or obese. Handgrip strength was weaker than the local norm. The subjects’ dominant handgrip strength, bilateral lifting, pushing, and pulling force were significantly correlated. Only bilateral lifting was significantly associated with MSD among the newly recruited health care workers.

Conclusions

This study reports the baseline prevalence of MSD symptoms in the newly recruited health care support staff. Their sedentary lifestyle and suboptimal physical strength may render them susceptible to occupational injuries and disease. An effective occupational health programme that provides periodic health surveillance should be considered for high-risk health care workers to allow proper interventions in a timely manner.

Distribution of Number, Location of Pain and Comorbidities, and Determinants of Work Limitations among Firefighters

INTRODUCTION

The unique demands of firefighting results in acute, recurrent, or chronic pain complications. We aimed to describe the percentage distribution of number and location of painful sites among FFs and determine whether work limitations differed based on the number or location of painful sites, age, and/or sex.

METHODS

About 325 firefighters completed a work limitation questionnaire (WLQ-26) and a checklist to indicate painful regions of the body using either a paper format or an online survey. A one-way ANOVA was employed to analyze the transformed work limitation scores; this was a two-sided test with a significance level of <0.05, to determine if work limitations differed among firefighters based on the number or location of painful sites, age, and/or sex.

RESULTS

The data analyzed consisted of 325 (men = 216, women = 109) FFs in total. The percentage distribution of the number of painful sites in our study cohort was 43% no pain, 17% one painful site, 19% two painful sites, and 21% three or more painful sites. The percentage distribution of the locations of painful sites was 43% no pain, 41% spine, 9% lower extremity, and 7% upper extremity. An estimated 31% of FFs (n = 102) reported non-MSK comorbidities with 23% (n = 76) reporting at least one non-MSK comorbidity and 8% (n = 26) reported having two or more comorbidities. FFs > 45 years of age experienced more physical work limitations than FFs ≤ 45years (mean difference: 0.74/10; 95% CI .19-1.29; p = 0.008).

CONCLUSIONS

The majority of firefighters reported having at least one painful site and indicated the spine as the most common painful location. Age, the number of painful sites, and location of pain were identified as a potential contributor to physical/mental and work output limitations.

Are blue-collar workers more physically active than white-collar at work?

This study evaluates the physical activity level at work and leisure time of white-collar and two groups of blue-collar workers from the latex glove industry and the association of physical activity level and musculoskeletal complains and work ability. The workers' sociodemographic and behavioral health characteristics, work ability index, musculoskeletal complains, total step count and caloric expenditure for three consecutive days, were assessed. The blue-collar workers that move most from the workstation (longD) were more physically active at work compared to white-collar and blue-collar that moved close the workstation (shortD). But in leisure-time the result is reversed, white-collar and blue-collar groups were significantly more active. There was no association between physical activity level and musculoskeletal pain intensity and work ability. All the groups of workers exhibited satisfactory physical activity levels, but only blue-collar (longD) were more physically active (10,000 steps per day).

Work-related injuries, postural stress, and musculoskeletal disorders among the railway track maintainers in India

The main aim of this cross-sectional study was to evaluate work-related injuries (WRI) and the self-reported musculoskeletal symptoms among 742 railway track maintainers. The second aim of this study was to investigate the potential factors related to the prevalence of musculoskeletal disorders (MSDs) in track maintainers. This study also tried to do planning and implementing ergonomic intervention programs to improve track maintainer’s health. Modified Nordic questionnaires were administered to assess the prevalence of MSDs. Detailed posture analysis by rapid entire body assessment (REBA) method was performed to assess the risk level of concerned postures. The injury data for 12 months were collected by conducting a survey and personal interviews with the affected railway track maintainers. To assess the prevalence of MSDs, the odds ratio and 95% confidence interval were computed along with critical χ 2 values. Analysis of variance was performed to determine significant differences between the MSD present and absent among the track maintainers of the Indian railway. The result of this study showed that neglect of safety precautions is the main reason for injury, followed by slipping and falling and lack of awareness. Sprain injury is one of the main injuries, followed by cut, snakebite, abrasion, and fracture. Low educational levels of workers are also reasons for WRI. In conclusion, the prevalence and severity of MSD, particularly in the low back, knees, wrist, and shoulder and WRI were found to be very high among the track maintainers. The recommendations of this research are ergonomic interventions, such as track maintainers proper training, following the National Institute of Occupational Safety and Health -recommended weight limit for manual material handling, modification in hand tools, job rotation, performing stretching exercise, and avoiding awkward and static posture are needed.

Risk Factors Associated with the Prevalence of Upper and Lower Back Pain in Male Underground Coal Miners in Punjab, Pakistan

There is not enough data available on occupational health and safety issues of underground coal miners in Pakistan. This study focuses on spinal disorders in association with personal and occupational factors. The Nordic Musculoskeletal Questionnaire was used for a cross-sectional study of 260 workers of 20 mines located in four districts of Punjab, Pakistan. Regression models were created for upper back pain and lower back pain of workers whose mean age is 19.8 years (±SD 1.47). Results identify the coal cutting as the most harmful work with odds ratios (ORs) 13.06 (95% confidence interval (CI) 13.7-21.5) for lower back pain and 11.2 (95% CI 3.5-19.4) for upper back pain in participants. Those with greater years of work experience had higher odds of upper back pain (2.4, 95% CI 1.4-3.5) and lower back pain (3.3, 95% CI 1.1-4.4). Number of repetitions (mean value 25.85/minute with ±SD 9.48) are also significant for spinal disorder with ORs of 4.3 (95% CI 3.2-7.4) for lower back and 1.3 (95% CI 1.0-2.4) for upper back. Many other occupational and personal factors are positively associated with the back pain in underground coal mines workers, requiring immediate ergonomic intervention.

Spinal loading and lift style in confined vertical space

The objective of this study was to investigate biomechanical loads on the lumbar spine as a function of working in a confined vertical space, consistent with baggage handling inside the baggage compartment of an airplane. Ten male subjects performed baggage handling tasks using confined (kneeling, sitting) and unconfined (stooping) lifting styles. Dependent measures of torso flexion and three-dimensional spinal loads were assessed with an electromyography-driven biomechanical model. Lifting exertions typical to airline baggage handling posed significant risk to the lumbar spine, regardless of lifting style. Statistically significant differences attributable to lift style (stooping, kneeling, sitting) were not observed for peak compressive, lateral shear, or resultant spinal loads, but lifting while kneeling decreased anterior/posterior (A/P) shear spinal loads relative to stooping (p = 0.02). Collectively, kneeling offers the greatest benefit when lifting in confined spaces because of the ability to keep the torso upright, subsequently reducing shear forces on the lumbar spine.

Occupational lifting predicts hospital admission due to low back pain in a cohort of airport baggage handlers

Purpose

To examine if occupational lifting assessed as cumulative years as a baggage handler is associated with first-time hospital diagnosis or treatment for low back disorders.

Methods

This study is based on the Copenhagen Airport Cohort consisting of male baggage handlers performing heavy lifting every day and a reference group of unskilled men from the greater Copenhagen area during the period 1990–2012. We followed the cohort in the National Patient Register and Civil Registration System to obtain information on diagnoses, surgery, mortality, and migration. The outcomes were first-time hospital diagnosis or surgery for (1) lumbar disc herniation or (2) low back pain (LBP).

Results

Baggage handlers (N = 3473) had a higher incidence rate of LBP, but not of lumbar disc herniation, compared to the reference group (N = 65,702). Baggage handlers with longer employment had a higher incidence of LBP compared to baggage handlers with shorter employment. The linear association of cumulative years as a baggage handler on LBP was significantly increased with an incidence rate ratio of 1.16 (95% CI 1.07–1.25) for a 5-year increase of employment as baggage handler.

Conclusions

In this large cohort study, we found an increased incidence of LBP among baggage handlers compared to the reference group with indications of a dose–response relationship between years of employment and the outcome. For baggage handlers working on the apron, the incidence was particularly increased before introduction of technical lifting equipment, suggesting that preventive measures to reduce cumulative work load may have a positive effect.

The Effects of a Stooped Work Task on the Muscle Activity and Kinematics of the Lower Back

Working in a stooped posture is an important risk factor for low back disorders (LBDs) that requires special focus. Spinal flexion increases the loading on the passive tissues of the lumbar spine compared to neutral postures, yet sustained or repeated flexion reduces the load bearing capability of these tissues. The objective of this study is to assess the effect of performing a stooped work task on the passive tissues of the low back. Passive tissue response is assessed by measuring trunk sagittal range of motion and the occurrence of the flexion-relaxation (F-R) phenomenon at specific times during the work period. Fourteen subjects (10 female and 4 male) were instrumented with a portable data collection system while performing the stooped work task of fresh-market tomato harvest for one hour in the morning and one hour in the afternoon. Results indicate significant changes in the trunk and lumbar sagittal range of motion and F-R after only 11 minutes of stooped work, with few changes for durations up to 55 minutes of work. The potential benefits of short, frequent rest breaks on recovery of passive tissue response are also demonstrated. The data collection device developed for this study allows for further investigation of the effects of stooped work on the lower back, which could lead to improved interventions to reduce LBD risk.

Lift performance and lumbar loading in standing and seated lifts

This study investigated the effect of posture on lifting performance. Twenty-three male soldiers lifted a loaded box onto a platform in standing and seated postures to determine their maximum lift capacity and maximum acceptable lift. Lift performance, trunk kinematics, lumbar loads, anthropometric and strength data were recorded. There was a significant main effect for lift effort but not for posture or the interaction. Effect sizes showed that lumbar compression forces did not differ between postures at lift initiation (Standing 5566.2 ± 627.8 N; Seated 5584.0 ± 16.0) but were higher in the standing posture (4045.7 ± 408.3 N) when compared with the seated posture (3655.8 ± 225.7 N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4 ± 104.4 N; Seated 224.2 ± 9.4 N) and completion (Standing 183.3 ± 62.5 N; Seated 71.0 ± 24.2 N) and may have been a result of increased trunk flexion and a larger horizontal distance of the mass from the L5-S1 joint. Practitioner Summary: Differences between lift performance and lumbar forces in standing and seated lifts are unclear. Using a with-in subjects repeated measures design, we found no difference in lifted mass or lumbar compression force at lift initiation between standing and seated lifts.

The ability of UK offshore workers of different body size and shape to egress through a restricted window space

404 male offshore workers aged 41.4 ± 10.7 y underwent 3D body scanning and an egress task simulating the smallest helicopter window emergency exit size. The 198 who failed were older (P < 0.01), taller (P < 0.05) and heavier (P < 0.0001) than the 206 who passed. Using all extracted dimensions from the scans, binary logistic regression identified a model (refined using backward elimination) which predicted egress outcome with 75.2% accuracy. Using only weight, bideltoid breadth and maximum chest depth, the model achieved ∼70% accuracy. When anatomical dimensions categorise individuals for small window egress, 25% or more will be misclassified, with false positives (those predicted to fail, but pass) slightly outnumbering false negatives (those predicted to pass, but fail), highlighting the limitations of a predictive approach which treats the body as a rigid object. Differences in flexibility and technique may explain these observations, which may be important considerations for future research.

Working postures and physical activity among registered nurses

Nurses report a high prevalence of musculoskeletal discomfort, particularly of the low back and neck/shoulder. This study characterized the full-shift upper arm and trunk postures and movement velocities of registered nurses using inertial measurement units (IMUs). Intensity of occupational physical activity (PA) was also ascertained using a waist-worn PA monitor and using the raw acceleration data from each IMU. Results indicated that nurses spent a relatively small proportion of their work time with the arms or trunk in extreme postures, but had few opportunities for rest and recovery in comparison to several other occupational groups. Comparisons between nurses in different PA groups suggested that using a combination of accelerometers secured to several body locations may provide more representative estimates of physical demands than a single, waist-worn PA monitor. The findings indicate a need for continued field-based research with larger sample sizes to facilitate the development of maximally effective intervention strategies.

Workplace Accidents and Work-related Illnesses of Household Waste Collectors

Background

Household waste collectors (HWCs) are exposed to hazardous conditions. This study investigates the patterns of workplace injuries and work-related illnesses of HWCs.

Methods

This study uses cases of workplace injuries and work-related illnesses of HWCs that occurred between 2010 and 2011. We analyzed 325 cases of injuries and 36 cases of illnesses according to the workers' age, length of employment, size of workplace, injured part of body, day and month of injury, type of accident, agency of accident, and collection process.

Results

There were significant differences in the effect of workers' length of employment, injured part of body, type of accident, agency of accident, and collection process. Results show that most injuries occur in workers in their 50s and older. This study also shows that 51.4% of injuries occur at businesses with 49 employees or fewer. Injuries to waste collectors happen most often when workers are electrocuted after slipping on the ground. The second most prevalent form of injury is falling, which usually happens when workers hang from the rear of the truck during transportation or otherwise slip and fall from the truck. Work-related illnesses amongst waste collectors are mostly musculoskeletal conditions due to damaging postures.

Conclusion

These findings will be instructive in devising policies and guidelines for preventing workplace injuries and work-related illnesses of HWCs.

Psychosocial Work Factors and Musculoskeletal Pain: A Cross-Sectional Study among Swedish Flight Baggage Handlers

OBJECTIVE

Flight baggage handlers sort and load luggage to airplanes. This study aimed at investigating associations between psychosocial exposures and low back and shoulder musculoskeletal disorders (MSDs) among Swedish flight baggage handlers.

METHODS

A questionnaire addressing MSDs (Standardized Nordic Questionnaire) and psychosocial factors (Copenhagen Psychosocial Questionnaire, COPSOQ) was answered by 525 baggage handlers in six Swedish airports.

RESULTS

Low back (LBP) and shoulder pain (SP) were reported by 70% and 60%, respectively. Pain was reported to interfere with work (PIW) by 30% (low back) and 18% (shoulders), and intense pain (PINT) occurred in 34% and 28% of the population. Quality of leadership was the most dissatisfying psychosocial factor, while the most positive was social community at work. Low ratings in the combined domain Work organization and job content were significantly associated with PIW in both low back and shoulders (Adjusted Hazard Ratios 3.65 (95% CI 1.67-7.99) and 2.68 (1.09-6.61)) while lower ratings in the domain Interpersonal relations and leadership were associated with PIW LBP (HR 2.18 (1.06-4.49)) and PINT LBP and SP (HRs 1.95 (1.05-3.65) and 2.11 (1.08-4.12)).

CONCLUSION

Severity of pain among flight baggage handlers was associated with psychosocial factors at work, suggesting that they may be a relevant target for intervention in this occupation.

Musculoskeletal health and work ability in physically demanding occupations: study protocol for a prospective field study on construction and health care workers

BACKGROUND

Musculoskeletal disorders have a profound impact on individual health, sickness absence and early retirement, particularly in physically demanding occupations. Demographics are changing in the developed countries, towards increasing proportions of senior workers. These senior workers may have particular difficulties coping with physically demanding occupations while maintaining good health. Previous studies investigating the relationship between physical work demands and musculoskeletal disorders are mainly based on self-reported exposures and lack a prospective design. The aim of this paper is to describe the background and methods and discuss challenges for a field study examining physical demands in construction and health care work and their prospective associations with musculoskeletal disorders, work ability and sickness absence.

METHODS AND DESIGN

This protocol describes a prospective cohort study on 1200 construction and health care workers. Participants will answer a baseline questionnaire concerning musculoskeletal complaints, general health, psychosocial and organizational factors at work, work demands, work ability and physical activity during leisure. A shorter questionnaire will be answered every 6th months for a total of two years, together with continuous sickness absence monitoring during this period. Analysis will prospectively consider associations between self-reported physical demands and musculoskeletal disorders, work ability and sickness absence. To obtain objective data on physical exposures, technical measurements will be collected from two subgroups of N = 300 (Group A) and N = 160 (Group B) during work and leisure. Both group A and B will be given a physical health examination, be tested for physical capacity and physical activity will be measured for four days. Additionally, muscle activity, ground reaction force, body positions and physical activity will be examined during one workday for Group B. Analysis of associations between objectively measured exposure data and the outcomes described above will be done separately for these subpopulations.

DISCUSSION

The field study will at baseline produce objectively measured data on physical demands in the construction and health care occupations. In combination with clinical measurements and questionnaire data during follow-up, this will provide a solid foundation to prospectively investigate relationships between physical demands at work and development of musculoskeletal disorders, work ability and sickness absence.

Precision markedly attenuates repetitive lift capacity

This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly.

PRACTITIONER SUMMARY

The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.

Work-Related Musculoskeletal Symptoms among Building Construction Workers in Riyadh, Saudi Arabia

Objectives: To investigate the work-related musculoskeletal symptoms among building construction workers.

Methods: Total 389 apparently healthy, male volunteers were selected with mean age 34.56±8.33 years and a mean working duration in building construction as 5.76±2.68 years. Musculoskeletal complaints were recorded through a detailed clinical interview and comprehensive questionnaire.

Results: Substantial number of building construction workers developed musculoskeletal symptoms including neck pain 29 (7.5%), shoulder pain 41(10.5%), upper back pain 24(6.2%), lower back pain 64 (16.5%), legs pain 93 (23.9%), feet pain 52 (13.4%), head heaviness 44 (11.3%) and whole body fatigue 78 (20.1%). These complaints were significantly associated with long-term duration-response in building construction industry. Furthermore, cigarette smokers had little higher percentage of musculoskeletal complaints compared to non-smoker companions.

Conclusions: Building construction occupation is a prolific source of musculoskeletal ailments and complaints were significantly increased with long-term working duration in building construction industry.

Gender specific analysis of occupational diseases of the low back caused by carrying, lifting or extreme trunk flexion--use of a prevention index to identify occupations with high prevention needs

BACKGROUND

Gender specific analysis of the occupational disease of the lumbar spine caused by carrying, lifting, or extreme trunk flexion in Germany (OD No.2108) with the aim to identify areas of focus for prevention and research with a prevention index (PI).

METHODS

Data from the German Statutory Accident Insurance stratified by gender are shown.

RESULTS

From 2002 until 2009 there were 2,877 confirmed cases of an OD No. 2108 (40.1% male and 59.1% female). The PI indicated the highest prevention need for female nursing/midwifery associate professionals and male building frame and related trades workers. Patient transfer and working in extremely bent posture were the most frequent exposures.

CONCLUSIONS

The identified occupations with high need for prevention among men come from nearly all major occupational groups whereas women cluster in occupational groups from the health and care sectors.

Description and analysis of hand forces in medicine cart pushing tasks

The primary objectives of this study were to describe and analyze the hand force exertion patterns of experienced nursing home nurses and nursing students during dynamic medicine cart pushing tasks in Initial, Sustained, Turning, and Stopping motion phases. A 2 × 2 × 2 factorial experiment was conducted with 22 participants to estimate the effects of lane congestion, precision cart control, and floor surface on horizontal hand forces. Root mean squared (RMS) lane deviation patterns were also described to provide an indicator of cart handling difficulty across the different study conditions. Descriptive statistics revealed that nurses exerted greater mean hand force (10%) and made more (12%) lane deviation than students and that the highest two-hand forces of 147N were measured in the Turning phase on carpet. Strong correlations between work experience group, body mass, and BMI required that force data for nurses and students be collapsed in analytical models where no group differences existed. Predicted pushing forces on carpeted floor surface were significantly greater than on tile in Initial (14N), Sustained (14N) and Turning (18N), except in stopping where pulling forces were 37N lower. High lane congestion predicted significant peak force increases of 4N and 7N in Sustained and Turning, respectively, but decreased by 20N in Initial. High precision control led to significant decreases in two-hand forces that ranged from 4 to 20N across motion phases. Complex interactions among the experimental factors suggest that work environment (lane congestion and floor surface) and work demands (precision control) should be included in the evaluation of pushing tasks and considered prior to making renovations to nursing home environments.

Shoulder joint loading and posture during medicine cart pushing task

Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used.

Differences in health complaints among Taiwanese workers in different occupational categories

OBJECTIVES

The objectives of this study were to determine the prevalence of and differences in certain health complaints, including physical symptoms and psychological distress, among workers in different occupational categories and to explore the associations between occupational category and each complaint.

METHODS

A cross-sectional study was conducted using a self-administered questionnaire. A total of 1,628 workers representing seven occupational categories from ten companies in different industries submitted completed questionnaires. The self-administered questionnaire contained three parts: personal data, physical symptoms and psychological distress. Physical symptoms were measured using nine questions developed by a panel of ten general practitioners; the questions included nine common physical symptoms across main organ systems. Psychological distress was measured using the Chinese Health Questionnaire.

RESULTS

Muscle pain (44.7%) and dizziness (30.1%) were the most common symptoms reported by participants, and 16.6% of participants suffered from psychological distress. Significant differences in physical symptoms and psychological distress were found among workers in different occupational categories (Χ(2)=53.59, p<0.001). Compared with service workers, office workers and managers had higher prevalence rates of physical symptoms; office workers also showed a higher prevalence of psychological distress.

CONCLUSIONS

The study merits attention in terms of prevention of health problems in the workplace by focusing on a set of physical symptoms and psychological distress (not merely morbidity). Occupational category should be taken into consideration when planning workplace health promotion. Our findings highlight the need for health promotion programs that specifically target office workers and managers.

Prevalence of musculoskeletal disorders among cashew factory workers

Work-related musculoskeletal disorders (WRMSDs) are impairments of the bodily structures, such as muscles, joints, tendons, ligaments, nerves, or the localized blood circulation system, which are caused or aggravated primarily by the performance of work and by the effects of the immediate environment in which work is carried out. Types of work in the cashew factory include cutting, peeling, grading, packing, and boiling. All these activities have risk factors for the musculoskeletal disorders, which include repetition, contact stress, forceful contraction, awkward postures, as well as sustained positions. The objective of this cross-sectional study was to find out the prevalence of musculoskeletal disorders among cashew factory workers. A cross-sectional descriptive study was conducted on 246 cashew factory workers, working in a randomly selected factory of a selected locality in Karkala taluk of Udupi district, Karnataka. Participants' name, age, gender, literacy level, income, type of work, duration of employment, hours of work per day, hand dominance, pain and discomfort status were obtained by structured interview. A total of 246 cashew factory workers participated in the study. Data were analyzed using SPSS version 14. Descriptive statistics was used to summarize the data. Around 28.5% (n = 70) reported pain, whereas 71.5% (n = 176) of workers did not report pain. The largest number of workers (n = 22; 32.4%) complained of pain in the knee, followed by back (n = 21; 30.9%) and then shoulder (n = 8; 11.8%). Seventy percent of the workers who reported pain were having more than 5 years of work experience. A 68.6% (n = 48) of the workers who reported pain were in the cutting category, followed by the grading (17%; n = 12), boiling (8.6%; n = 6), and peeling (5.7%; n = 4) categories. Prevalence of pain and discomfort among workers was 28.5%, which is a not ignorable and has to be addressed. Self-reported pain and discomfort were more prevalent in knee, followed by back and then shoulder.

Individual participant data meta-analysis of mechanical workplace risk factors and low back pain

OBJECTIVES

We used individual participant data from multiple studies to conduct a comprehensive meta-analysis of mechanical exposures in the workplace and low back pain.

METHODS

We conducted a systematic literature search and contacted an author of each study to request their individual participant data. Because outcome definitions and exposure measures were not uniform across studies, we conducted 2 substudies: (1) to identify sets of outcome definitions that could be combined in a meta-analysis and (2) to develop methods to translate mechanical exposure onto a common metric. We used generalized estimating equation regression to analyze the data.

RESULTS

The odds ratios (ORs) for posture exposures ranged from 1.1 to 2.0. Force exposure ORs ranged from 1.4 to 2.1. The magnitudes of the ORs differed according to the definition of low back pain, and heterogeneity was associated with both study-level and individual-level characteristics.

CONCLUSIONS

We found small to moderate ORs for the association of mechanical exposures and low back pain, although the relationships were complex. The presence of individual-level OR modifiers in such an area can be best understood by conducting a meta-analysis of individual participant data.

An analysis of injury claims from low-seam coal mines

INTRODUCTION

The restricted workspace present in low-seam coal mines forces workers to adopt awkward working postures (kneeling and stooping), which place high physical demands on the knee and lower back.

METHOD

This article provides an analysis of injury claims for eight mining companies operating low-seam coal mines during calendar years 1996-2008. All cost data were normalized using data on the cost of medical care (MPI) as provided by the U.S. Bureau of Labor Statistics.

RESULTS

Results of the analysis indicate that the knee was the body part that led in terms of claim cost ($4.2 million), followed by injuries to the lower back ($2.7 million). While the average cost per injury for these body parts was $13,100 and $14,400, respectively (close to the average cost of an injury overall), the high frequency of these injuries resulted in their preeminence in terms of cost. Analysis of data from individual mining companies suggest that knee and lower back injuries were a consistent problem across companies, as these injuries were each among the top five most costly part of body for seven out of eight companies studied. APPLICATION/IMPACT: Results of this investigation suggest that efforts to reduce the frequency of knee and low back injuries in low-seam mines have the potential to create substantial cost savings.

Evaluation of proper height for squatting stool

Many jobs and activities in people's daily lives have them in squatting postures. Jobs such as housekeeping, farming and welding require various squatting activities. It is speculated that prolonged squatting without any type of supporting stool would gradually and eventually impose musculoskeletal injuries on workers. This study aims to examine the proper height of the stool according to the position of working materials for the squatting worker. A total of 40 male and female college students and 10 female farmers participated in the experiment to find the proper stool height. Student participants were asked to sit and work in three different positions: floor level of 50 mm; ankle level of 200 mm; and knee level of 400 mm. They were then provided with stools of various heights and asked to maintain a squatting work posture. For each working position, they were asked to write down their thoughts on a preferred stool height. A Likert summated rating method as well as pairwise ranking test was applied to evaluate user preference for provided stools under conditions of different working positions. Under a similar experimental procedure, female farmers were asked to indicate their body part discomfort (BPD) on a body chart before and after performing the work. Statistical analysis showed that comparable results were found from both evaluation measures. When working position is below 50 mm, the proper stool height is 100 or should not be higher than 150 mm. When working position is 200 mm, the proper stool height is 150 mm. When working position is 400 mm, the proper stool height is 200 mm. Thus, it is strongly recommended to use proper height of stools with corresponding working position. Moreover, a wearable chair prototype was designed so that workers in a squatting posture do not have to carry and move the stool from one place to another. This stool should ultimately help to relieve physical stress and hence promote the health of squatting workers. This study sought to evaluate and make suggestions on user preference and BPD of proper stool height, at which work can be done comfortably, according to squatting work position. In short, results showed that proper stool height differed according to working position, even with similar squatting tasks.

Manual materials handling in mining: the effect of rod heights and foot positions when lifting "in-the-hole" drill rods

There is a paucity of studies focusing on the lifting of rods or long awkward heavy objects. In-the-hole (ITH) drilling is a heavy repetitive mining task, which has been identified as having a relatively high incidence and severity rate of musculoskeletal injuries. The purpose of this study was to examine how the load experienced by ITH drill operators changed when lifting a vertical drilling rod (1.61m, 35kg) using two rod heights and four different foot positions. In addition, a symmetrical lift with a lifting index (LI) of 1.4 also served as a comparison to determine possible risk of low back injury. Eleven experienced ITH drill operators participated in the study. Each subject was required to lift a vertical drilling rod until the upper body was in an erect posture using four different foot positions (0 degrees =subject facing the rod, 45 degrees =subject oblique to the rod, 90 degrees =subject right side to the rod and freestyle). In addition, two rod height conditions were studied where the base of the vertical rod was supported either (1) at ground level (height of rod CG=0.83m) or (2) on a 20cm rack (height of rod CG=1.03m). Finally, each subject lifted a 21.5kg box in the sagittal plane, which corresponded to an LI of 1.4 in the NIOSH lifting equation. Reflective markers were placed on the subjects, and three video cameras and one force plate were used to record the forces and the motion of the subjects' segments. Two surface electrodes were applied on the right and the left erector spinae (ES) at the level of L3. Back loading was defined by the level of the peak moments, the mechanical work and erector spinae muscle activity (EMG). It was found that the vertical height of the rod had the most significant impact on back loading, while the effect of the initial foot positioning relative to the rod was limited by the technique adopted by the drillers. Moreover, it was found that some of the subjects used techniques less strenuous for the back than others. Finally, the asymmetrical lifting component was found to be the most negative aspect of lifting an ITH drill rod compared to a standard symmetrical lift (NIOSH).