Task variation during simulated, repetitive, low-intensity work – influence on manifestation of shoulder muscle fatigue, perceived discomfort and upper-body postures

Abstract

Work-related musculoskeletal disorders are increasing due to industrialisation of work processes. Task variation has been suggested as potential intervention. The objectives of this study were to investigate, first, the influence of task variation on electromyographic (EMG) manifestations of shoulder muscle fatigue and discomfort; second, noticeable postural shoulder changes over time; third, if the association between task variation and EMG might be biased by postural changes. Outcome parameters were recorded using multichannel EMG, Optotrak and the Borg scale. Fourteen participants performed a one-hour repetitive Pegboard task in one continuous and two interrupted conditions with rest and a pick-and-place task, respectively. Manifestations of shoulder muscle fatigue and discomfort feelings were observed throughout the conditions but these were not significantly influenced by task variation. After correction for joint angles, the relation between task variation and EMG was significantly biased but significant effects of task variation remained absent.Practitioner Summary: Comparing a one-hour continuous, repetitive Pegboard task with two interrupted conditions revealed no significant influences of task variation. We did observe that the relation between task variation and EMG was biased by posture and therefore advise taking account for posture when investigating manifestations of muscle fatigue in assembly tasks.

Is rotating between static and dynamic work beneficial for our fatigue state?

“…The cranial shift in the standardised protocols might reflect the tendency to elevate the shoulder complex in order to relief the constantly active shoulder muscle parts (e.g., Luger et al, 2015;Samani et al, 2010). This explanation may support the psychophysical findings somewhat, as reported in the previous paragraph.…”

“…The electrode rows were placed in line with the muscle fibre directions of both muscles with an inter electrode distance (IED) of 15 mm (for details, see Luger et al, 2015). Muscle activity of the right Deltoid pars Clavicularis, Acromialis and Spinalis was measured with a bipolar EMG configuration (IED 20 mm) according to the Seniam guidelines (Hermens et al, 2000).…”

Getting nowhere fast: trade-off between speed and precision in training to execute image-guided hand-tool movements

“…Although there is general agreement that human cognitive processes from an integrative component of computerassisted interventional technologies, we still do not know enough about how human performance and decision making is affected by these technologies [34]. The pressing need for research in this domain reaches far beyond the realms of workflow analysis and task models (e.g.…”

Influence of Posture Variation on Shoulder Muscle Activity, Heart Rate, and Perceived Exertion in a Repetitive Manual Task

“…Increased variation in biomechanical exposures may be obtained by changing the content of individual tasks, by changing the time pattern of these tasks, or by introducing new tasks. Examples of interventions include the design of workstations or other equipment, introduction of additional breaks (Galinsky et al, 2007;Henning, Jacques, Kissel, Sullivan Alteras-Webb, 1997;Luger, Bosch, Hoozemans, De Looze, & Veeger, 2015), re-arrangement of breaks through the working day (Balci & Aghazadeh, 2003;Dababneh, Swanson, & Shell, 2001), and job rotation (Luger, Bosch, Hoozemans, Veeger, & De Looze, 2016;Riss en, Melin, Sandsj€ o, Dohns, & Lundberg, 2002;Roquelaure et al, 1997). A recent review of studies investigating biomechanical exposure variation by Luger, Bosch, Veeger, and De Looze (2014) concluded that the evidence for positive effects of increased exposure variation on indicators of fatigue is limited.…”