2014-05-01 12:00 - Messages

A longitudinal study on risk factors for neck and shoulder pain among young adults in the transition from technical school to working life

Objectives: The study examined the course of neck and shoulder pain among a cohort of technical school students entering working life. We also aimed to identify work-related and individual risk factors for neck and shoulder pain during this transition period.
Methods: The study was designed as a prospective cohort study following 420 technical school students (167 student hairdressers, 118 student electricians, and 135 media/design students) from school, through their apprenticeship and into working life. Every 4th month over a 6.5 year period (2002–2009), the participant`s neck and shoulder pain for the preceding four weeks was assessed. Mechanical and psychosocial workplace factors as well as individual factors were evaluated at baseline and/or during the follow-up period. Data were analyzed by generalized estimating equations (GEE).
Results: We found a significant increase in neck and shoulder pain over time in the transition from technical school to working life. High mechanical workload was associated with neck and shoulder pain among women, while a high level of shoulder muscle endurance capacity was associated with lower rates of neck and shoulder pain among men. Perceived muscle tension and ethnicity were the most consistent predictors for neck and shoulder pain, found among both women and men.
Conclusion: Increased neck and shoulder pain was found in the transition from technical school to working life, and both work-related and individual factors were associated with pain development.

Source: Hanvold TN, Wærsted M, Mengshoel AM, Bjertness E, Twisk J, Veiersted KB. Scand J Work Environ Health. 2014.

Determining Safe Limits for Significant Task Parameters During Manual Lifting

This experimental study investigated the effect of lifting task parameters (i.e., lifting weight, frequency, coupling, asymmetric angle, and vertical, horizontal, and travel distances) for various dynamic human lifting activities on the ground reaction forces of workers. Ten male workers loaded containers from different levels asymmetrically during experimental trials. The experimental design evolved using Taguchi's Fractional Factorial Experiments. Three factors (lifting weight, frequency, and vertical distance) were observed to be significant. The results showed that vertical reaction forces increase when workers lift weight from floor to shoulder height frequently. It was also observed that instantaneous loading rate increases with more weight, vertical distance, and frequency; a significant extra loading rate is required to change the lower level of load, frequency, and vertical distance to higher levels. Safe limits for significant factors were determined to result in optimal performance of the manual lifting task.

Source: Pratrap Singh, Ravindra, Batish, Ajay, et Singh, Tejinder Pal. (2014). Workplace Health & Safety, 62(4), 150-160.

The assessment of material handling strategies in dealing with sudden loading

The effects of load handling position on trunk biomechanics
Back injury caused by sudden loading is a significant risk among workers that perform manual handling tasks. The present study investigated the effects of load handling position on trunk biomechanics (flexion angle, L5/S1 joint moment and compression force) during sudden loading. Eleven subjects were exposed to a 6.8 kg sudden loading while standing upright, facing forward and holding load at three different vertical heights in the sagittal plane or 45° left to the sagittal plane (created by arm rotation).
Results showed that the increase of load holding height significantly elevated the peak L5/S1 joint compression force and reduced the magnitude of trunk flexion. Further, experiencing sudden loading from an asymmetric direction resulted in significantly smaller peak L5/S1 joint compression force, trunk flexion angle and L5/S1 joint moment than a symmetric posture. These findings suggest that handling loads in a lower position could work as a protective strategy during sudden loading.

Source: Ning X, Zhou J, Dai B, Jaridi M. Appl. Ergon. 2014.

Shoulder muscle loading and task performance for overhead work on ladders versus mobile elevated work platforms

A high incidence of Musculoskeletal Disorders (MSDs) has been reported in the construction sector. The use of ladders in the workplace has long been identified as a significant risk that can lead to workplace accidents. However, it is unclear if platform types have an effect on the physical risk factors for MSDs in overhead work. The aim of this study is to perform a pilot study on the effects of hand activity on both shoulder muscle loading and task performance while working on ladders versus Mobile Elevated Working Platforms (MEWPs). It is hypothesised that work on ladders would result in greater muscle loading demands, increased levels of discomfort, and reduced performance due to the restrictions on postures that could be adopted. A field study (n = 19) of experienced electricians on a construction site found that workers spent approximately 28% of their working time on ladders versus 6% on MEWPs. However, the durations of individual tasks were higher on MEWPs (153 s) than on ladders (73 s). Additionally, maximum levels of perceived discomfort (on a VAS 0-100) were reported for the shoulders (27), neck (23), and lower regions of the body (22). A simulated study (n = 12) found that task performance and discomfort were not significantly different between platform types (ladder vs. MEWP) when completing either of three tasks: cabling, assembly and drilling. However, platform and task had significant effects (p < 0.05) on median electromyographic (EMG) activity of the anterior deltoid and upper trapezius. EMG amplitudes were higher for the deltoid than the upper trapezius. For the deltoid, the peak amplitudes were, on average, higher for ladder work over MEWP work for the hand intensive cabling (32 vs. 27% Maximal Voluntary Exertion (MVE)) and the assembly task (19 vs. 6% MVE). Conversely, for drilling, the peak EMG amplitudes were marginally lower for ladder compared to the MEWP (3.9 vs. 5.1% MVE). The general implication was that working on the MEWP involved lower shoulder muscle loading for cabling and assembly task. A difference due to platform type was not present for drilling work.

Source: Phelan D, O'Sullivan L. Appl. Ergon. 2014.

Barriers to change in depressive symptoms following multidisciplinary rehabilitation for whiplash

The role of perceived injustice
OBJECTIVE: Depressive symptoms complicate patients' recovery following musculoskeletal injury. There is strong evidence to support the utility of multidisciplinary approaches for treating comorbid pain and depressive symptoms. Despite this, a significant proportion of patients may not experience meaningful reductions in depressive symptoms following intervention. The purpose of this study was to identify barriers to change in depressive symptom during multidisciplinary rehabilitation for patients with whiplash injuries.
METHODS: 53 patients with clinically meaningful levels of depressive symptoms prior to participating in a standardized multidisciplinary rehabilitation program participated in this study. Patients completed self-report measures of depressive symptoms, demographic factors, pain intensity, disability, post-traumatic stress symptoms, pain catastrophizing and self-efficacy upon commencement and completion of the rehabilitation program. Analyses examined whether pre-treatment variables predicted change in depressive symptoms over treatment and the maintenance of clinically meaningful levels of depressive symptoms at post-treatment.
RESULTS: Duration of work absence and perceived injustice were significant unique predictors of percent change in depressive symptoms in a linear regression analysis. Perceived injustice was the only significant unique predictor of the presence of clinically meaningful levels of depressive symptoms at post-treatment in a logistic regression analysis.
CONCLUSIONS: The results suggest that the identification of patients with high levels of perceived injustice and implementation of targeted interventions for these patients might contribute to greater improvements in their depressive symptomatology.

Source: Scott W, Trost Z, Milioto M, Sullivan MJ. Clin. J. Pain. 2014.

Systems thinking applied to safety during manual handling tasks in the transport and storage industry

Injuries resulting from manual handling tasks represent an on-going problem for the transport and storage industry. This article describes an application of a systems theory-based approach, Rasmussen's (1997. Safety Science 27, 183), risk management framework, to the analysis of the factors influencing safety during manual handling activities in a freight handling organisation. Observations of manual handling activities, cognitive decision method interviews with workers (n=27) and interviews with managers (n=35) were used to gather information about three manual handling activities. Hierarchical task analysis and thematic analysis were used to identify potential risk factors and performance shaping factors across the levels of Rasmussen's framework. These different data sources were then integrated using Rasmussen's Accimap technique to provide an overall analysis of the factors influencing safety during manual handling activities in this context. The findings demonstrate how a systems theory-based approach can be applied to this domain, and suggest that policy-orientated, rather than worker-orientated, changes are required to prevent future manual handling injuries.

Source: http://www.safetylit.org/citations/index.php?fuseaction=citations.viewdetails&citationIds[]=citjournalarticle_437197_8

Work-related musculoskeletal disorders on the decline in Ontario

Work-related musculoskeletal disorders appear to be on the decline in Ontario. That's what findings from a comprehensive population-based surveillance study recently done by the Institute for Work & Health (IWH) would suggest.
The study, led by IWH president Dr. Cameron Mustard, tracks the occurrence of work-related musculoskeletal disorders (MSDs) over eight years between 2004 and 2011. It uses three independent population databases to take a count of work-related MSDs as reported by the total number of Ontarians active in the labour force in that time period—a sample of about six million.
What's important about this study is that it drew on three different data sources,” says Mustard. “And because they vary somewhat in how they define work-related MSDs, there are differences in incidence estimates between the three data sources. But all three show a steady decline.
This finding supports what several other studies in industrialized countries such as Australia, the Netherlands, the United States and the United Kingdom have found. The study, which has been submitted for publication in the Scandinavian Journal of Work, Environment and Health, is the first surveillance study on work-related MSDs done in Canada in recent times.

Source: At Work, Issue 76, Spring 2014.

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