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Does Your Organization Measure Ergonomic Push/Pull Forces Correctly?

Have you ever noticed that carts vary wildly in their ease of being pushed and pulled? Many organizations try to prevent carts from being too difficult to push and pull by implementing ergonomic push/pull standards in their facilities. These standards are put in place in order to prevent ergonomic sprain and strain injury to employees. Pushing and pulling as a form of manual materials handling presents a high risk for low back disorders (LBDs), accounting for at least 10% of LBD workers’ compensation claims, also resulting in production downtime.

Now, you may be wondering how these organizations decide upon acceptable push/pull thresholds for their employees. Well, quite often, they set internally-acceptable limits based off of the manual material handling tables of Snook and Ciriello 1991 and ISO-11228-2. These tables set widely-accepted, yet subjectively determined, limits for hand force during pushing and pulling. Using these tables, organizations make their own tweaks and methods of push/pull force measurement based upon their own processes.

Push/Pull Guage

When organizations measure push/pull force with their own methods, this poses perhaps the greatest challenge to communicate the performance capabilities of an incredibly important ergonomic component of a cart: the caster. This challenge has lead Caster Connection to become very interested in ergonomics and the push/pull standards that our clients adhere to. In 2018, The Ohio State University Spine Research Institute (SRI) published a set of biomechanically determined push/pull risk limits that link hand forces produced during push/pull exertions to the subsequent risk of low back injury in the working population. During ergonomics assessments, practitioners often record these hand forces using a single-axis force gauge (particularly, the force required to initiate movement of the object from a standstill). Although use of a single-axis force gauge is ideal for portable measurements, the hand forces recorded by practitioners are often imprecise or even inaccurate because force measurements are affected by conditions of the field test itself, including the acceleration of the cart, angle of applied push/pull force, and more. The objective of this particular study is to provide recommendations for practitioners in regard to push/pull force assessment that improves the accuracy and precision of hand force estimates, thus making the SRI push/pull guidelines more applicable.


In order to bring clarity to this common issue, Caster Connection is collaborating with The Ohio State University Spine Research Institute (SRI) to once and for all establish a “gold standard” for push/pull testing for any organization, in any industry. This collaboration is taking place within the NSF Industry/University Cooperative Research Center (I/UCRC) Ohio State University’s MSD Prevention Site. These efforts will focus on developing measurement guidelines that more closely equate the SRI push/pull guidelines. These guidelines will reduce variability in hand forces measured by hand transducers. As of right now, many factors affect accurate and consistent measurement results. These factors could include (but are not limited to) cart acceleration, force gauge accessories, straight/perpendicular wheels, flooring surface, etc. These new guidelines will benefit practitioners as they attempt to estimate the biomechanical risk associated with a particular push/pull task and will allow for the most high-risk push/pull tasks to be redesigned more effectively.

Downtime is a Four Letter Word - Caster Connection - January 2019 - Ohio State University

Why is Caster Connection undertaking this endeavor? We are undertaking this project because Caster Connection is dedicated to providing the most innovative and optimal solutions in order to deliver enhanced ergonomics, safety, and efficiency for every client, whether or not the best solution is our product or one we can find for you elsewhere.

More details to come throughout 2019.