The study focused on pressmen working at print facilities of a major U.S. news publishing company. Ergonomic analysis identified excessive workplace injuries to the neck and shoulder, most commonly the rotator cuff on the right side.
Three activities were targeted for intervention: blanket washing, newsprint roll handling and pre-drive belt positioning wheel adjustments. With the use of SEMG, researchers determined whether improvements to the workstation, worker technique or both were more likely to lower the risk of injury while performing these tasks. Two active electrodes, placed parallel to the targeted muscles (the left and right upper trapezius and the left and right lumbar paraspinals), collected data.
The researchers found that some of the workers’ movements might save time, but not injury. While washing the blanket cylinder, for example, a worker typically would put one hand on the control panel to manipulate the inch-safe buttons and simultaneously reach for the cylinder with the other hand. These actions require awkward movements that make the muscles work harder.
One solution was to retrain the worker not to perform these tasks simultaneously. By keeping the non-cleaning arm at rest, the cleaning task could be performed less strenuously. Alternatively, the researchers introduced a 4-foot-long metal pole that included two ergonomic handles and a cleaning head. Through SEMG assessment, this supplement to the workstation combined with a modification of worker behavior brought about an even greater reduction in strenuous muscle activity while the worker performed the same task.
The article, “Surface Electromyography-Assisted Ergonomic Analysis in a Newspaper Printing Plant: A Case Study,” appeared in the Winter 2010 issue of the journal Biofeedback and can be downloaded as a PDF.