A weblog dedicated to Ergonomics education, dicussion and debate. This emerging field has the power to transform industry, business and the lives of ordinary people for the better. The Industrial Athlete intends to encourage and document our profession's vision of an ergonomically-friendly future!

Friday, February 10, 2006

How-To: Reducing Non-Neutral Shoulder Postures

Today, I will be continuing an ongoing series of primers to help our readers identify non-neutral body postures. Today's area of focus is the shoulder. The shoulder is a loosely-bound confluence of body structures, being the meeting place of the humerus (upper arm) and the clavicle (collarbone). As such, unnecessary work-related stress can put the joint at risk for injury.

There are 3 major situations where the shoulder can be found outside of its neutral orientation:


Problem: The work system/object in question is outside of the operator's optimal envelope of reach (12"), forcing them to reach forward, putting their shoulder into a position known as flexion.

Solution: Bring the work system/object closer to the operator so that they are within 12" optimally, and no further than 18". Eliminate/reduce any physical barriers that prevent the operator from getting sufficiently close to their work, provided that eliminating that physical barrier does not compromise safety.


Problem: The operator interacts with work systems/objects behind them out of neccesity/habit, or pulls a cart instead of pushing it.

Solution: Situate the work systems/objects in front or the side of the operator, placing the controls/objects within 12" of the operator optimally, and no more than 18" overall. Have the worker use a push cart rather than one that is pulled, as it uses larger muscle groups than pulling does, thus reducing the damaging effects of chronic muscle fatigue (Source: OSHA)


Problem: The work surface is too high for the work being performed on it, causing the operator to shrug their shoulders. Work systems/objects accessed above shoulder level also causes shrugging of the shoulders.

Solution: Adjust the working height so that fall within the parameters of the work that is being performed. The work surface should be between 37.5" - 47" for precision tasks, 33.5" - 43" for light work, and 26" - 37" for heavy work (Source: CCOHS). All work surfaces should be fully adjustable to allow for appropriate micro adjustments. All work systems/objects should be accessible below shoulder level as much as humanly possible.


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