2018-08-01 12:00 - Messages

Economic evaluation of a randomized controlled trial of an intervention to reduce office workers’ sitting time: the "Stand Up Victoria" trial

Multicomponent intervention involving a sit-and-stand desk can reduce sitting time and increase the standing and stepping time during the working hours for office-based workers, and it is likely to promote the cardiovascular fitness. It is cost-effective in the long-term from a societal perspective. This study provides important evidence for policy-makers and workplaces regarding allocation of resources to reduce workplace sitting.

Source: Gao, L., Flego, A., Dunstan, D. W., Winkler, E. A., Healy, G. N., Eakin, E. G., ... et Wiesner, G. H. (2018). Scandinavian journal of work, environment & health.

Hand forces exerted by long-term care staff when pushing wheelchairs on compliant and non-compliant flooring

Purpose-designed compliant flooring and carpeting have been promoted as a means for reducing fall-related injuries in high-risk environments, such as long-term care. However, it is not known whether these surfaces influence the forces that long-term care staff exert when pushing residents in wheelchairs. We studied 14 direct-care staff who pushed a loaded wheelchair instrumented with a triaxial load cell to test the effects on hand force of flooring overlay (vinyl versus carpet) and flooring subfloor (concrete versus compliant rubber [brand: SmartCells]). During straight-line pushing, carpet overlay increased initial and sustained hand forces compared to vinyl overlay by 22–49% over a concrete subfloor and by 8–20% over a compliant subfloor. Compliant subflooring increased initial and sustained hand forces compared to concrete subflooring by 18–31% when under a vinyl overlay. In contrast, compliant flooring caused no change in initial or sustained hand forces compared to concrete subflooring when under a carpet overlay.

Source: Lachance, C. C., Korall, A. M., Russell, C. M., Feldman, F., Robinovitch, S. N. et Mackey, D. C. (2018). Applied ergonomics, 71, 95-101.

Conceptual frameworks for the workplace change adoption process

Elements integration from decision making and learning cycle process
Sound workplace ergonomics and safety-related interventions may be resisted by employees, and this may be detrimental to multiple stakeholders. Understanding fundamental aspects of decision-making, behavioural change, and learning cycles may provide insights into pathways influencing employees' acceptance of interventions. This manuscript reviews published literature on thinking processes and other topics relevant to decision making and incorporates the findings into two new conceptual frameworks of the workplace change adoption process. Such frameworks are useful for thinking about adoption in different ways and testing changes to traditional intervention implementation processes. Moving forward, it is recommended that future research focuses on systematic exploration of implementation process activities that integrate principles from the research literature on sense-making, decision-making, and learning processes. Such exploration may provide the groundwork for development of specific implementation strategies that are theoretically grounded and provide a revised understanding of how successful intervention adoption processes work.

Source: Radin Umar, R. Z., Sommerich, C. M., Lavender, S. A., Sanders, E. et Evans, K. D. (2018). Ergonomics.

The influence of job rotation and task order on muscle responses in females

Job rotation aims to reduce muscle fatigue by switching between functionally different tasks to theoretically lessen the risk of site-specific fatigue and work-related musculoskeletal disorders (WMSDs). The effectiveness of job rotation in mitigating the onset of muscle fatigue is partially known, but there is limited ergonomic data on female populations despite comparatively lower upper body strength and increased risk of WMSDs. Rotating between two functionally different tasks, continuing a single task, and varying task order were assessed in the present study for influence on muscle fatigue indicators in a female population. Participants performed a randomized set of four task combinations involving two unilateral, repetitive shoulder tasks (forward flexion and internal rotation). During these combinations, maximal voluntary force, mean power frequency, average EMG (aEMG) and ratings of perceived exertion (RPE) were recorded. Differences between task combinations and time were tested using a two-way repeated measures ANOVA. Indications of fatigue were limited in the results. Forward flexion (p?=?0.004) and internal rotation (p?=?0.002) maximum voluntary force declined in all task combinations while RPE increased (p?<?0.0001); non-rotating task combinations had the greatest declines in force and increases in RPE. Results from EMG amplitude were less clear, and were muscle and task specific. While non-rotating task combinations had the greatest decrements in aEMG submaximal force, rotating task combinations often had similar decrements, creating limited statistical differences. Changes in aEMG were too small to distinguish an order effect. The EMG results suggest muscular demand overlap between the two tasks, despite being functionally different. The effectiveness of job rotation is partially dependent on selecting tasks that engage distinct muscle groups.

Source: Dickhout, K. D., MacLean, K. F. et Dickerson, C. R. (2018). International Journal of Industrial Ergonomics, 68, 15-24.

Surface electromyography for risk assessment in work activities designed using the “revised NIOSH lifting equation”

The aims of this study were: to identify surface electromyography (sEMG)-based indices of trunk muscles acquired during the execution of lifting tasks designed using the revised NIOSH lifting equation and featuring a progressively increasing lifting index (LI); to study changes of these indices in relation to the LI; to evaluate the relationship between the identified indices and forces (FL5−S1) and moments (ML5−S1) at the L5-S1 joint. sEMG, kinematic and kinetic data of 20 male workers were recorded in three conditions. We computed the average rectified value (ARV), root mean square (RMS) and maximum value (Max) of twelve trunk muscles and the muscle co-activation. We also estimated FL5−S1 and ML5−S1. One-way repeated-measures ANOVA and post-hoc analysis showed that sEMG-based indices values increased with LI increment of 1 (LI?=?l, 2 and 3). sEMG and kinetic parameters were linearly correlated.
Findings suggest a promising use of wearable sEMG sensors in developing instrumental-based risk assessment tools in either the laboratory or workplace. In fact, some indices discriminate the investigated risk levels and correlate with the variables that generate the damage.

Source: Ranavolo, A., Varrecchia, T., Iavicoli, S., Marchesi, A., Rinaldi, M., Serrao, M., ... et Draicchio, F. (2018). International Journal of Industrial Ergonomics, 68, 34-45.

How does the biomechanical exposure of the upper body in manual box handling differ from exposure in other tasks in the real industrial context?

The assessment of biomechanical exposure during handling tasks in relation to other activities that are performed in industrial settings can be crucial to understand the biomechanical demands of manual box handling for the upper limbs. This study aims to evaluate the representativeness of the handling task to the upper body in comparison with the other tasks in a real setting, compare the biomechanical exposure between tasks, and identify the differences in exposure during manual box handling from job exposure. Twelve workers had biomechanical exposure assessed through trapezius muscle activity and posture recordings (upper back and upper arms) during 4?h of a regular working day. Handling tasks demonstrated the highest biomechanical demand to the upper body, particularly for peak loads of the upper trapezius activation and upper back forward flexion postures. However, handling tasks were also associated with a high exposure variation. Interventions aiming to decrease loads in handling tasks can be relevant to decreasing peak loads and avoiding musculoskeletal disorders on the upper limbs.

Source: Nogueira, H. C., Locks, F., Barbieri, D. F. et Oliveira, A. B. (2018). International Journal of Industrial Ergonomics, 68, 8-14.

Workplace interventions for reducing sitting at work

Background: A large number of people are employed in sedentary occupations. Physical inactivity and excessive sitting at workplaces have been linked to increased risk of cardiovascular disease, obesity, and all-cause mortality.
Objectives: To evaluate the effectiveness of workplace interventions to reduce sitting at work compared to no intervention or alternative interventions.

Source: Shrestha, N., Kukkonen-Harjula, K.T., Verbeek, J.H., Ijaz, S., Hermans, V. et Pedisic, Z. (2018). Cochrane Database of Systematic Reviews, 6.

Elongation of the surface of the spine during lifting and lowering, and implications for design of an upper body industrial exoskeleton

The aim of this study was to assess the elongation of the skin surface of the spine for simulated industrial lifting and lowering tasks to aid the design of industrial exoskeletons worn on the back. Eighteen male participants lifted and lowered a box of varying loads (5?kg, 10?kg, 15?kg) using three techniques (squat, semi-squat, stooped) from the ground to a table. Motion capture sensors attached to the spine from C7 to S1 measured movement. Stoop lifting involved significantly more elongation (mean 71.1?mm; margin of error ±6.9) than squat lifting (mean 36.8?mm; margin of error ±6.9). Load and Task (lift vs. lower) did not have a significant effect on elongation. Elongation of the skin surface of the lumbar spine was greater than for the thoracic spine. These data detail example levels of elongation of the skin surface of the spine, which should be considered in upper body wearable industrial exoskeleton design. Further, exoskeleton design should take into account that the skin surface of the lumbar spine involves greater elongation than the skin surface of the thoracic spine during deep lifting.

Source: Huysamen, K., Power, V. et O'Sullivan, L. (2018). Applied ergonomics, 72, 10-16.

Effects of standing on typing task performance and upper limb discomfort, vascular and muscular indicators

Standing is a popular alternative to traditionally seated computer work. However, no studies have described how standing impacts both upper body muscular and vascular outcomes during a computer typing task. Twenty healthy adults completed two 90-min simulated work sessions, seated or standing. Upper limb discomfort, electromyography (EMG) from eight upper body muscles, typing performance and neck/shoulder and forearm blood flow were collected. Results showed significantly less upper body discomfort and higher typing speed during standing. Lower Trapezius EMG amplitude was higher during standing, but this postural difference decreased with time (interaction effect), and its variability was 68% higher during standing compared to sitting. There were no effects on blood flow. Results suggest that standing computer work may engage shoulder girdle stabilizers while reducing discomfort and improving performance. Studies are needed to identify how standing affects more complex computer tasks over longer work bouts in symptomatic workers.

Source: Fedorowich, L. M. et Côté, J. N. (2018). Applied ergonomics, 72, 121-127.

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