Quantifying relationships between selected work-related risk factors and back pain: a systematic review of objective biomechanical measures and cost-related health outcomes

Spinal loads during dynamic full flexion and return to standing posture in different age and sex groups: A musculoskeletal model study

During forward flexion, spine motion varies due to age and sex differences. Previous studies showed that lumbar/pelvis range of flexion (RoF) and lumbo-pelvic ratio (L/P) are age/sex dependent. How variation of these parameters affects lumbar loading in a normal population requires further assessment. We aimed to estimate lumbar loads during dynamic flexion-return cycle and the differences in peak loads (compression) and corresponding trunk inclinations due to variation in lumbar/pelvis RoF and L/P. Based on in vivo L/P (0.11-3.44), temporal phases of flexion (early, middle, and later), the lumbar (45-55°) and hip (60-79°) RoF; full flexion-return cycles of six seconds were reconstructed for three age groups (20-35, 36-50 and 50+ yrs.) in both sexes. Six inverse dynamic analyses were performed with a 50th percentile model, and differences in peak loads and corresponding trunk inclinations were calculated. Peak loads at L4-L5 were 179 N higher in younger males versus females, but 228 N and 210 N lower in middle-aged and older males, respectively, compared to females. Females exhibited higher trunk inclinations (6°-20°) than males across all age groups. Age related differences in L4-L5 peak loads and corresponding trunk inclinations were found up to 415 N and 19° in males and 152 N and 13° in females. With aging, peak loads were reduced in males but were found non-monotonic in females, whereas trunk inclinations at peak loads were reduced in both sexes from young to middle/old age groups. In conclusion, lumbar loading and corresponding trunk inclinations varied notably due to age/sex differences. Such data may help distinguishing normal or pathological condition of the lumbar spine.

Prevalence of work-related musculoskeletal disorders and quality of life assessment among garment workers in Tiruppur district, Tamil Nadu

Objectives. The garment industry is a labour-intensive industry, with workers susceptible to musculoskeletal problems, especially those employed in smaller units that lack adequate occupational health provisions. This study aims to determine the prevalence of work-related musculoskeletal disorders (WMSDs) among workers in both large and small garment units and assess their quality of life (QoL). Methods. The study surveyed 746 garment workers, comprising 372 from large units and 374 from small units. Data were collected through the Nordic musculoskeletal questionnaire and the World Health Organization Quality of Life (WHOQOL)-BREF questionnaire, with posture analysis conducted using the rapid upper limb assessment (RULA) and rapid entire body assessment (REBA) scales. Results. The results showed that 32% of workers in large-scale garment units and 43.9% in small-scale garment units reported musculoskeletal symptoms. The occurrence of musculoskeletal disorders (MSDs) was significantly associated with increasing age, smoking, alcohol consumption, job duration, working in shifts and moonlighting. Conclusion. The workers in the garment industry, particularly of small units, are highly susceptible to WMSDs.

A holistic methodology for mitigating awkward postural risks: Evidence from South Indian small-scale industries

BACKGROUND

Small-scale industries (SSI) are the global economy's backbone since most industrial workers are connected. Most of these workers are contractual and temporary without appropriate training. Also, the SSI does not have a standard workplace with an appropriate layout and infrastructure, as they manage with minimum resources. Therefore, the work hazards, i.e., musculoskeletal disorders and fatigue, often go unnoticed as holistic postural risk methodology is still scarce for identifying the awkward postures in SSI.

OBJECTIVE

The present study proposes a novel holistic methodology to track and mitigate awkward postural risks in human-physical activities in SSI. To determine the effectiveness of the proposed methodology, a case study is presented in the South Indian Pump industry, wherein a critical workstation with a complex ergonomic work environment is employed.

METHODS

An ergonomic evaluation was conducted empirically and numerically in the workplaces using Digital Human Models. In numerical evaluation, three virtual workspaces have been created to redesign the identified crucial workstation, focusing on ergonomics and workflow.

RESULTS

The results obtained from the case study are encouraging for to use of the novel methodology in SSI. The case study reports that the proposed design significantly reduced the REBA score and WISHA lifting index by 6 and 1.20, respectively, without significant investment.

CONCLUSION

The proposed methodology could encourage research to identify awkward posture in SSI.

Evaluating Different Measures of Low Back Pain Among U.S. Manual Materials Handling Workers: Comparisons of Demographic, Psychosocial, and Job Physical Exposure

OBJECTIVE

To examine differences in demographic, psychosocial, and job physical exposure risk factors between multiple low back pain (LBP) outcomes in a prospective cohort of industrial workers.

BACKGROUND

LBP remains a leading cause of lost industrial productivity. Different case definitions involving pain (general LBP), medication use (M-LBP), seeking healthcare (H-LBP), and lost time (L-LBP) are often used to study LBP outcomes. However, the relationship between these outcomes remains unclear.

METHOD

Demographic, health status, psychosocial, and job physical exposure risk factors were quantified for 635 incident-eligible industrial workers. Incident cases of LBP outcomes and pain symptoms were quantified and compared across the four outcomes.

RESULTS

Differences in age, gender, medical history, and LBP history were found between the four outcomes. Most incident-eligible workers (67%) suffered an LBP outcome during follow-up. Cases decreased from 420 for LBP (25.4 cases/100 person-years) to 303 for M-LBP (22.0 cases/100 person-years), to 151 for H-LBP (15.6 cases/100 person-years), and finally to 56 for L-LBP (8.7 cases/100 person-years). Conversely, pain intensity and duration increased from LBP to H-LBP. However, pain duration was relatively lower for L-LBP than for H-LBP.

CONCLUSION

Patterns of cases, pain intensity, and pain duration suggest the influence of the four outcomes. However, few differences in apparent risk factors were observed between the outcomes. Further research is needed to establish consistent case definitions.

APPLICATION

Knowledge of patterns between different LBP outcomes can improve interpretation of research and guide future research and intervention studies in industry.

A comparison of augmented feedback and didactic training approaches to reduce spine motion during occupational lifting tasks

Manual handling training may be improved if it relied on the provision of individualized, augmented feedback about key movement features. The purpose of this study was to compare the reduction in sagittal spine motion during manual lifting tasks following two training approaches: didactic (DID) and augmented feedback (AUG). Untrained participants (n = 26) completed lifting tests (box, medication bag, and paramedic backboard) and a randomly-assigned intervention involving 50 practice box lifts. Lifting tests were performed immediately before and after training, and one-week after interventions. Both groups exhibited reductions in spine motions immediately and one-week after the interventions. However, the AUG intervention group elicited significantly greater reductions in 5 of 12 between-group comparisons (3 tasks × 4 spine motion variables). The results of the current study support the use of augmented feedback-based approaches to manual handling training over education-based approaches.

Functional Analysis of the Spine with the Idiag SpinalMouse System among Sedentary Workers Affected by Non-Specific Low Back Pain

WHO describes “low back pain” (LBP) as the most common problem in overall occupational-related diseases. The aim of this study was to evaluate characteristics of spinal functionality among sedentary workers and determine usability of the SpinalMouse^® skin-surface measurement device in workplace settings in a risk population for LBP. The spinal examination was implemented at National Instruments Corporations’ Hungarian subsidiary, Debrecen in October, 2015, involving 95 white-collar employees as volunteers to assess spinal posture and functional movements. Data from the physical examination of 91 subjects (age: 34.22 ± 7.97 years) were analyzed. Results showed significant differences (p < 0.05) in posture and mobility of the spinal regions in sitting compared to standing position. Significant positive correlations were observed between values measured in standing and sitting positions in all observed regions and aspects of the spine (p < 0.05) except posture of lumbar extension (p = 0.07) and mobility of sacrum/hip in E-F (p = 0.818). Significant (p < 0.001) difference (5.70°) was found between the spinal inclination in sitting 6.47 ± 3.55° compared to standing 0.77 ± 2.53 position. Sitting position has a negative effect on the posture and mobility of the spine among white-collar employees. The SpinalMouse can be used effectively to determine spinal posture and mobility in cross-sectional studies and impact analysis of physical exercise interventions.

Feasibility of quantifying the physical exposure of materials handlers in the workplace with magnetic and inertial measurement units

Handling tasks can expose workers to risk factors. The objective was to describe the feasibility of using magnetic and inertial measurement units (MIMUs) to quantify the physical exposure of materials handlers in the workplace. Full-body kinematics were obtained with MIMUs on 10 handlers gathering products ordered by retailers with a pallet truck. An observer classified the visual difference (VD) of segment orientation between a MIMUs avatar and video recordings in three categories (none, minor and major) for each product transfer. The feet, arms, shoulders and head were considered similar for ≥97% of observations. The trunk segment obtained the most differences with 9% of minor VD and 5% of major VD, which were related to the duration of the magnetic disturbances of the MIMUs. Estimating parameters of the physical exposure of handlers in the workplace is feasible with kinematics and an order list, but visual verification remains important for scientific rigour.Practitioner Summary: The feasibility of measuring physical exposure with magnetic and inertial measurement units was evaluated on materials handlers in the workplace. Visual observation of the postures indicated that most of the data is considered acceptable. Magnetic disturbances can increase the measurement error, so data must be verified to ensure validity.

A machine-learning method for classifying and analyzing foot placement: Application to manual material handling

Foot placement strategy is an essential aspect in the study of movement involving full body displacement. To get beyond a qualitative analysis, this paper provides a foot placement classification and analysis method that can be used in sports, rehabilitation or ergonomics. The method is based on machine learning using a weighted k-nearest neighbors algorithm. The learning phase is performed by an observer who classifies a set of trials. The algorithm then automatically reproduces this classification on subsequent sets. The method also provides detailed analysis of foot placement strategy, such as estimating the average foot placements for each class or visualizing the variability of strategies. An example of applying the method to a manual material handling task demonstrates its usefulness. During the lifting phase, the foot placements were classified into four groups: front, contralateral foot behind, ipsilateral foot behind, and parallel. The accuracy of the classification, assessed with a holdout method, is about 97%. In this example, the classification method makes it possible to observe and analyze the handler's foot placement strategies with regards to the performed task.

Whole body biomechanical burden of healthcare workers: proposal for a complementary risk assessment and management tool (HOARA)

Introduction:

We have developed a new tool, named Holistic Approach Risk Assessment (HOARA), to support occupational safety and health professionals (OSH) in risk assessment and management when evaluating the biomechanical load of healthcare workers.

Objectives:

The primary aim of the HOARA is to support OSH in risk assessment and management of biomechanical hazards in healthcare facilities. This tool ensures a superior level of analysis by targeting independently various body compartments during all activities completed throughout the work shift. These include: head, neck, back and upper and lower limbs.

Methods:

For each body segment, ergonomic determinants were defined on the basis of previous literature, according to which task and job analyses were performed. Upon direct observation, ergonomic factors were given a score based on their temporal extent. Subsequently, action-body segment raw indices and weighted indices were calculated.

Results:

Results of the application of the method are shown. Of note, a relational database was set up to improve its usability.

Conclusions:

From an occupational health perspective, the HOARA, integrated with other methods, is expected to allow a more effective management of human resources, especially when assigning workers to specific jobs or tasks. Overall, the HOARA will be instrumental in assessing the impact of fitness for work judgments on work organization and its resources, in compliance with the guidelines from the Società Italiana di Medicina del Lavoro (SIML).

Impact of Lifting of Two Types of Barrels on Postural Control, Trunk Muscle Recruitment, and Kinematic Measures in Manual Workers

The aim of this study was to evaluate the impact of 2 types of beer barrels on postural control, trunk activation, and kinematic measures in adult workers. Twelve (12) males randomly performed 4 tasks on a force platform for 20 s: (1) hold an empty recyclable barrel, (2) hold a full recyclable barrel (30 L), (3) hold an empty steel barrel, and (4) hold a full steel barrel (30 L). Trunk muscular activation, force platform and kinematic measures at the trunk, hip, and knee joints were computed. The full steel barrel produced greater postural oscillation than other conditions. Higher trunk activity was also reported during the full steel barrel task. Significant kinematic changes only in the trunk were observed between the empty steel barrel and the full recyclable barrel tasks. In conclusion, the full steel barrel produced a negative impact on postural control, increasing trunk activity and changing trunk flexion angle in adult workers.

Using visual aids to influence manual lifting techniques: acute effects of viewing static images on spine motion

Purpose. This study aimed to determine whether untrained observers alter their spine as directed via static images of different lifting techniques. Methods. Ten men and eight women, who had no lifting or visual observation training, performed box lifts. Following a self-selected lifting technique trial, participants performed four experimental lifting trials (in randomized order) wherein they were instructed to execute lifts in accordance with the techniques pictured. These techniques differed by the amount of knee, trunk and spine flexion modeled. Peak lumbar flexion angles and flexion/extension velocities were quantified, and then statistically analyzed via general linear models with two within-participant factors (condition = technique; phase = lift/lower). Results. Lumbar flexion angles and flexion/extension velocities differed between conditions (p < 0.001), although the effects depended on the combination of postural characteristics pictured. A main effect of phase was observed for peak lumbar flexion velocity only (p = 0.001). No condition × phase interaction effects were detected for any dependent variables (p > 0.050). Conclusions. Acute changes in lifting mechanics can be elicited via visual observation of pictured techniques. However, if using pictures to attenuate peak lumbar flexion displacements and velocities when lifting, auxiliary instruction may be needed to direct observers' attention to the spine curvature displayed.

Prevalence of work related musculoskeletal disorders (WMSDs) and ergonomic risk assessment among readymade garment workers of Bangladesh: A cross sectional study

BACKGROUND

Work related Musculoskeletal Disorders (WMSDs) are one of the most common occupational diseases which mainly affects the lower back, neck and upper and lower extremities. The aim of this study was to determine prevalence of WMSDs in nine body regions among Ready Made Garment (RMG) workers in Bangladesh and ergonomics assessment of their exposure to risk factors for the development of WMSDs.

METHODS

This cross-sectional study was conducted among 232 RMG employees (male: 46; female: 186; age: >18yrs) from nine RMG factories in Dhaka division during October 2015 to February 2016. Data were collected using a structured questionnaire consist of demographic questions, Nordic Musculoskeletal Questionnaire-Extended (NMQ-E) for WMSDs assessment in nine body regions and Quick Exposure Check (QEC) method for ergonomic assessment. Prevalence of WMSDs for each body region was determined. The association between WMSDs and ergonomic assessment of their exposure to risk factors were also analyzed.

RESULTS

Respondents' mean age was 31.3 years (SD = 7). Their mean Body Mass Index (BMI) was 23.51 kg/m2 (SD = 3.74). Among 186 female respondents, 46 reported lower back pain (24.7%) and 44 reported neck pain (23.7%). Among 46 male respondents, 10 reported neck pain (21.7%) while 6 reported knee pain (13%). Statistically significant relationship was found between twelve month WMSDs in anatomical region in elbows (p = 0.02), hips (p = 0.01), knees (p = 0.01) and ankle (p = 0.05) with age; upper back (p = 0.001), elbows (p = 0.001), wrists (p = 0.03), hips (p = 0.001) and ankles (p = 0.01) with job experience; hips with BMI (p = 0.03); elbows (p = 0.04) with daily working hour. QEC assessment showed that level of exposure to WMSDs risk was high among 80% of the study population (p<0.003).

CONCLUSION

The study found that lower back and neck were the most affected areas among RMG workers. Moreover, QEC findings warned the level of exposure to WMSDs risks is high and ergonomics intervention along with investigation and change to decrease exposure level is essential. Addressing musculoskeletal risk factors through ergonomic interventions in terms of working space, workers sitting/standing posture, seat and hand position during work and work-rest cycle are encouraged in RMG sector and policy makers.

Economic evaluations of ergonomic interventions preventing work-related musculoskeletal disorders: a systematic review of organizational-level interventions

BACKGROUND

Work-related musculoskeletal disorders (WMSD) represent a major public health problem and economic burden to employers, workers and health insurance systems. This systematic review had two objectives: (1) to analyze the cost-benefit results of organizational-level ergonomic workplace-based interventions aimed at preventing WMSD, (2) to explore factors related to the implementation process of these interventions (obstacles and facilitating factors) in order to identify whether economic results may be due to a successful or unsuccessful implementation.

METHODS

Systematic review. Studies were searched in eight electronic databases and in reference lists of included studies. Companion papers were identified through backward and forward citation tracking. A quality assessment tool was developed following guidelines available in the literature. An integration of quantitative economic results and qualitative implementation data was conducted following an explanatory sequential design.

RESULTS

Out of 189 records, nine studies met selection criteria and were included in our review. Out of nine included studies, grouped into four types of interventions, seven yielded positive economic results, one produced a negative result and one mixed results (negative cost-effectiveness and positive net benefit). However, the level of evidence was limited for the four types of interventions given the quality and the limited number of studies identified. Our review shows that among the nine included studies, negative and mixed economic results were observed when the dose delivered and received by participants was low, when the support from top and/or middle management was limited either due to limited participation of supervisors in training sessions or a lack of financial resources and when adequacy of intervention to workers' needs was low. In studies where economic results were positive, implementation data showed strong support from supervisors and a high rate of employee participation.

CONCLUSION

Studies investigating the determinants of financial outcomes of prevention related to implementation process are very seldom. We recommend that in future research economic evaluation should include information on the implementation process in order to permit the interpretation of economic results and enhance the generalizability of results. This is also necessary for knowledge transfer and utilization of research results for prevention-oriented decision-making in occupational health and safety.

Effects of Holding an External Load on the Standing Balance of Older and Younger Adults With and Without Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to assess the effect of holding an external load on the standing balance of younger and older adults with and without chronic low back pain (CLBP).

METHODS

Twenty participants with and 20 without CLBP participated in the study. Each group contained 10 younger (50% men) and 10 older adults (50% men). Participants were instructed to look straight ahead while standing on a force platform during two 120-second trials with and without holding an external load (10% of body mass). The center of pressure area, mean velocity, and mean frequency in the anteroposterior and mediolateral directions were measured.

RESULTS

Older adults had worse standing balance than younger adults did (P < .001, d = 0.20). There were no significant balance differences between participants with and without CLBP within age groups during standing balance condition. However, holding the external load significantly increased postural instability for both age groups and CLBP status, with mean effect size across center of pressure variables of d = 0.82 for older participants without CLBP and d = 2.65 for younger participants without CLBP. These effects for people with CLBP were d = 1.65 for subgroup of older and d = 1.60 for subgroup of younger participants.

CONCLUSION

Holding an external load of 10% of body mass increased postural instability of both younger and older adults with and without CLBP.

Difference between male and female workers lifting the same relative load when palletizing boxes

A few biomechanical studies have contrasted the work techniques of female and male workers during manual material handling (MMH). A recent study showed that female workers differed from males mostly in the strategy they used to lift 15-kg boxes from the ground, especially regarding task duration, knee and back postures and interjoint coordination. However, the lifting technique difference observed in females compared to males was perhaps due to a strength differences. The objective of this study was to test whether female workers would repeat the same lifting technique with a load adjusted to their overall strength (females: 10 kg; males: 15 kg), which can be considered a "relative load" since the overall back strength of females is 2/3 that of males. The task for the participants consisted in transferring boxes from one pallet to another. A dynamic 3D linked segment model was used to estimate the net moments at L5/S1, and different kinematic variables were considered. The results showed that the biomechanics of the lifting techniques used by males and females were similar in terms of task duration and cumulative loading, but different in terms of interjoint coordination pattern. The sequential interjoint coordination pattern previously seen in females with an absolute load (15 kg) was still present with the relative load, suggesting the influence of factors more intrinsically linked to sex. Considering that the female coordination pattern likely stretched posterior passive tissues when lifting boxes from the ground, potentially leading to higher risk of injury, the reason for this sex effect must be identified so that preventive interventions can be proposed.

Health-related employer support, recurring pain, and direct insurance costs for a self-insured employer

BACKGROUND

Poor psychosocial workplace factors have been found to cause or exacerbate a variety of health problems, including pain. However, little work has focused on how psychosocial workplace factors, such as health-related employer support, relate to future medical expenditures after controlling for health. Health-related support has also not been well explored in previous literature as a psychosocial factor. This study estimated the association of health-related employer support and pain with future medical expenditures, after including many additional controls.

METHODS

This study used a restricted data set comprised of medical claims and survey data for one company in the U.S. Participants were included in the sample if they had worked for their employer for at least 12 months prior to the survey and if they were continuously eligible for health insurance (N=1,570). Future medical expenditures were measured using administrative claims data covering inpatient, outpatient, mental health and pharmaceutical insurance claims during a year. Health-related employer support was measured using participants' answers about whether the employer would support their efforts to positively change their emotional or physical health. Pain was measured as recurring pain from any condition over the previous year.

RESULTS

Having any physical health-related employer support was associated with a 0.06 increase in the probability of having future medical expenditures greater than zero, 95% CI [0.01, 0.11], but not with total expenditures. Having pain was associated with a 0.06 increase, 95% CI [0.04, 0.09], in the probability of having future medical expenditures greater than zero and with $3,027 additional total expenditures, 95% CI [$1,077, $4,987].

CONCLUSIONS

After controlling for health and pain, psychosocial workplace factors were not robustly associated with future medical expenditures. Pain was associated with increased medical expenditures for the self-insured employer in this study, adjusting for a variety of factors.

Pre-employment examination for low back risk in workers exposed to manual handling of loads: French guidelines

BACKGROUND

Low back pain (LBP) is a major cause of sickness absence and disability in the working population, and the pre-employment examination should insure that worker's state of health is compatible with the requirements of proposed job. This paper summarizes the main recommendations of the good practice guidelines of the French Society of Occupational Medicine for pre-employment examination in workers exposed to manual handling of loads apart from pre-employment test.

METHODS

The recommendations were developed according to the Clinical Practice Guidelines proposed by the French National Health Authority and based on a systematic search of the literature 1990-2012 in several databases. The guidelines were written and reviewed by two multidisciplinary committees. On the basis of the level of evidence in the literature, the proposed guidelines are classified as grade A, B, C or expert consensus.

RESULTS

The main recommendations of these guidelines are as follows: (1) medical contraindications alone should not exclude employment in a job associated with a low back risk on the basis of a history of "simple" nonspecific LBP; (2) the relevance of examining a previous history of LBP, which is the best predictor of future LBP due to the recurrent nature of LBP.

CONCLUSIONS

These guidelines correspond to a constant concern with prevention of occupational risk. Primarily intended for occupational physicians, they are also intended for general practitioners who carry out pre-employment examinations in many countries and are likely to be increasingly faced with this type of situation because of the combination of increasing work constraints with ageing of the workforce.

Recurring pain and the potential of employer support to improve participant health

OBJECTIVE

This study describes the relationships between a set of workplace psychosocial factors, including health-related employer support and recurring pain.

METHODS

This study used a pooled sample of participants from 14 US employers (N = 34,359) from 2010 (for one employer, 2008). Multiple logistic regression was used to estimate the relationships, after controlling for many additional factors.

RESULTS

Emotional, but not physical, health-related employer support was associated with reduced probability of pain. Job satisfaction, getting to use strengths at work, and having a supervisor who created a trusting and open environment were also associated with a reduced probability of pain.

CONCLUSIONS

Although more research is needed to firmly establish the causal nature of the relationships, psychosocial workplace factors were associated with reduced probability of pain in this study.

Sex differences in lifting strategies during a repetitive palletizing task

Forty-five manual material handlers (15 females, 15 expert males and 15 novice males) performed series of box transfers under conditions similar to those of large distribution centers. The objective of the study was to verify whether sex differences in joint motions and in back loading variables (L5/S1 moments) exist during multiple box transfers. The task consisted in transferring 24 15-kg boxes from one pallet to another (4 layers of boxes; 6 boxes/layer: 3 in the front row, 3 in the back) at a self-determined pace and then at an imposed pace of 9 lifts/min. Full-body 3D kinematic data were collected as well as external foot forces. A dynamic 3D linked segment model was used to estimate the net moments at L5/S1. The results show that the peak L5/S1 moment during lifting for females was significantly lower than for males, but once normalized to body size the difference disappeared. In general, the female workers were very close to the posture adopted by the novice males at the instant of the peak resultant moment. However, females were closer to the box than the male workers. One major sex difference was seen when lifting from the ground, with the use of interjoint coordination analyses. Female workers showed a sequential motion initiated by the knees, followed by the hip and the back, while expert males showed a more synchronized motion. The lifting strategy of females likely stretches lumbar spine passive tissues, which in turn put them at greater risk of back injuries. As observed in our previous studies, these differences between expert males, novice males and females are especially notable when the box is lifted from the ground.

Lifting strategies of expert and novice workers during a repetitive palletizing task

Thirty manual material handlers (15 experts and 15 novices) were invited to perform series of box transfers under conditions similar to those of large distribution centers. The objective of the present study was to verify whether multiple box transfers leading to fatigue would also lead to differences between expert and novice workers in joint motions and in back loading variables (L5/S1 moments). The task consisted in transferring 24 15-kg boxes from one pallet to another (4 layers of boxes; 6 boxes/layer: 3 in the front row, 3 in the back) at a self-determined pace and then at an imposed pace of 9 lifts/min for a total of 240 lifts. The underlying idea was to set a challenging task that would force the experts to use their skills. Full-body 3D kinematic data were collected as well as external foot forces. A dynamic 3D linked segment model was used to estimate the net moments at L5/S1. The results clearly show that the experts bent their lumbar spine less (10° less) and were closer (4 cm) to the box than novice workers. Knee flexions were similar in both groups except when the box was lifted from ground level (expert ≈ 71°, novice ≈ 48°). The peak resultant moment was not statistically different (expert = 168 Nm, novice = 184 Nm) although experts had lower values on average than novices when lifting heights (and deposit heights) of the boxes increased. Therefore, experts differed from novice workers mostly in the posture-related variables. These differences are especially important to consider when the box is located on the ground, as the back posture and back loading are then at their greatest magnitude and could have a major impact on the distribution of internal forces on the spine.

The NIOSH lifting equation and low-back pain, Part 1: Association with low-back pain in the backworks prospective cohort study

OBJECTIVE

The aim of this study was to evaluate relationships between the revised NIOSH lifting equation (RNLE) and risk of low-back pain (LBP).

BACKGROUND

The RNLE is commonly used to quantify job physical stressors to the low back from lifting and/or lowering of loads. There is no prospective study on the relationship between RNLE and LBP that includes accounting for relevant covariates.

METHOD

A cohort of 258 incident-eligible workers from 30 diverse facilities was followed for up to 4.5 years. Job physical exposures were individually measured. Worker demographics, medical history, psychosocial factors, hobbies, and current LBP were obtained at baseline. The cohort was followed monthly to ascertain development of LBP and quarterly to determine changes in job physical exposure. The relationship between LBP and peak lifting index (PLI) and peak composite lifting index (PCLI) were tested in multivariate models using proportional hazards regression.

RESULTS

Point and lifetime prevalences of LBP at baseline were 7.1% and 75.1%, respectively. During follow-up, there were 123 incident LBP cases. Factors predicting development of LBP included job physical exposure (PLI and PCLI), history of LBP, psychosocial factors, and housework. In adjusted models, risk (hazard ratio [HR]) increased per-unit increase in PLI and PCLI (p = .05 and .02; maximum HR = 4.3 and 4.2, respectively). PLI suggested a continuous increase in risk with an increase in PLI, whereas the PCLI showed elevated, but somewhat reduced, risk at higher exposures.

CONCLUSION

Job physical stressors are associated with increased risk of LBP. Data suggest that the PLI and PCLI are useful metrics for estimating exposure to job physical stressors.

Trunk postures and upper-body muscle activations during physically demanding wildfire suppression tasks

This study examined the trunk postures and upper-body muscle activations during four physically demanding wildfire suppression tasks. Bilateral, wireless surface electromyography was recorded from the trapezius and erector spinae muscles of nine experienced, wildfire fighters. Synchronised video captured two retroreflective markers to allow for quantification of two-dimensional sagittal trunk flexion. In all tasks, significantly longer time was spent in the mild and severe trunk flexion (p ≤ 0.002) compared to the time spent in a neutral posture. Mean and peak muscle activation in all tasks exceeded previously established safe limits. These activation levels also significantly increased through the performance of each task (p < 0.001). The results suggest that the wildfire suppression tasks analysed impose significant musculoskeletal demand on firefighters. Fire agencies should consider developing interventions to reduce the exposure of their personnel to these potentially injurious musculoskeletal demands.

Innovative system for real-time ergonomic feedback in industrial manufacturing

This work presents a system that permits a real-time ergonomic assessment of manual tasks in an industrial environment. First, a biomechanical model of the upper body has been developed by using inertial sensors placed at different locations on the upper body. Based on this model, a computerized RULA ergonomic assessment was implemented to permit a global risk assessment of musculoskeletal disorders in real-time. Furthermore, local scores were calculated per segment, e.g. the neck region, and gave information on the local risks for musculoskeletal disorders. Visual information was fed back to the user by using a see-through head mounted display. Additional visual highlighting and auditory warnings were provided when some predefined thresholds were exceeded. In a user study (N = 12 participants) a group with the RULA feedback was compared to a control group. Results demonstrate that the real-time ergonomic feedback significantly decreased the outcome of both globally as well as locally hazardous RULA values that are associated with increased risk for musculoskeletal disorders. Task execution time did not differ between groups. The real-time ergonomic tool introduced in this study has the potential to considerably reduce the risk of musculoskeletal disorders in industrial settings. Implications for ergonomics in manufacturing and user feedback modalities are further discussed.

Stakeholder perspectives on managing the occupational health of UK business drivers: a qualitative approach

Musculoskeletal disorders are one of the leading causes of work related ill health and sickness absence. Those who drive as part of their job may be at particular risk, with evidence suggesting that prolonged exposure to driving is associated with increased absence from work due to low back pain. Business drivers often work away from a traditional office environment. Such mobile working may pose greater risks to occupational health due to increased ergonomic risks, for example working from the car, longer working hours and a lack of concern amongst drivers about health and safety. It has been suggested that occupational health practices have not adapted to meet the needs of peripatetic workers. The current study explored how occupational health services are delivered to business drivers. Semi-structured interviews were carried out with a sample of 31 stakeholders in 4 organisations. Respondents included, health and safety professionals, occupational health nurses, fleet managers and high mileage business drivers. The interviews were transcribed and analysed using 'Template Analysis'. The data revealed that, within these organisations, the provision of occupational health services was often fragmented and drivers and other key stakeholders were often unaware of the existing systems within their organisations. The peripatetic nature of business drivers meant that they were difficult for occupational health teams to reach. The paper concludes by presenting recommendations for occupational health professionals and researchers engaged with improving the health of peripatetic workers, namely that occupational health policies should be integrated in company strategy and widely disseminated to drivers and those with responsibility for managing their occupational health provision.

The influence of kinesiophobia on trunk muscle voluntary responses with pre-programmed reactions during perturbation in patients with chronic low back pain

The purpose of this study was to examine the relation between fear of movement and perturbation induced electromyographic global trunk muscle voluntary responses with pre-programmed reactions among persons with chronic low back pain (CLBP). CLBP subjects (n = 25) were challenged to unexpected and expected perturbations on stable and unstable surfaces. 'Tampa scale for kinesiophobia - Adjusted version-13' was used to measure kinesiophobia. Regression analysis revealed significant negative correlation between kinesiophobia scores and voluntary responses of rectus abdominis (RA) for unexpected perturbations on stable (r = -0.69, 95% of CI: -0.85 to -0.40, p < 0.000, r(2) = 0.41) and unstable surfaces (r = -0.47, 95% of CI: -0.72 to -0.09, p < 0.018, r(2) = 0.29). The activity of erector spinae was not influenced by most of testing conditions in the study except task on unstable surface for expected perturbation (r = -0.593, 95% of CI: -0.8 to -0.25, p = 0.002, r(2) = 0.15). RA activity and kinesiophobia score of the CLBP population was significantly inversely associated during anteriorly directed unexpected perturbations. In our study, the significant association between fear of movement and the trunk muscle responses was differentially influenced by expected and unexpected postural demands.