A New Way Of Judging Ergonomic Performance: An Objective Set Of Push/Pull Guidelines From The Ohio BWC/Ohio State University Spine Research Institute

The long-term reason for this was to “…protect workers from disabling musculoskeletal disorders (MSDs). The more immediate goal [was] the development and dissemination of pushing and pulling workplace guidelines that [would] help minimize MSDs.”[2]

The results of this grant funding led to the OSU SRI publishing An Objective Set of Guidelines for Pushing and Pulling, and these guidelines are now expected to be protective of both the low back and shoulders. These objectively determined guidelines are in contrast to the widely-accepted, subjectively determined limits for hand force during pushing and pulling that are included in the manual material handling tables of Snook and Ciriello 1991.

The SRI summarizes their document by explaining

Current guidelines related to pushing and pulling commonly used by practitioners were developed using subjective methods and may underestimate risk to the lower back and shoulders. This document describes the development of a new set of objective guidelines and how to implement them moving forward to help reduce the risk of workplace injury to the low back and shoulders.[3]

According to the SRI, subjectively developed guidelines rely on

the assumption that an individual’s perception of maximum acceptable external forces corresponds to biomechanical risk to the low back and shoulders (Snook and Ciriello 1991). Prior literature shows this assumption is incorrect (Jorgensen et al. 1999; Davis et al. 2000; Le et al. 2012).

The OSU SRI explains how they developed objective push/pull guidelines by stating

This study used biomechanical information collected from 62 human subjects in a laboratory to develop pushing and pulling guidelines for practitioners. This was achieved via establishing a relationship between the biomechanical loads induced onto the spine and hand forces generated by the participants. Risk limits were determined by investigating which hand forces or turning torques led to spinal loads over risk thresholds (Gallagher and Marras 2012; NIOSH 1981). Loads on the spine were predicted using a unique biomechanical model that is validated for pushing and pulling, dynamic, and accurately accounts for the way each person recruits their muscles to complete a task (Granata and Marras 1993; Hwang et al. 2016; Knapik and Marras 2009). Subjects performed activities including 1 Handed Pulling, 2 Handed Pulling, and 2 Handed Pushing. They performed exertions at three different handle heights (32 in, 40 in, 48 in) and performed both straight and turning push/pull exertions.

The objectively determined push/pull guidelines developed as a result of this study were therefore published within An Objective Set of Guidelines for Pushing and Pulling and have been used to inform the web interface BWC/OSU Push/Pull Guidelines on the Ohio BWC website. The web interface is intended to function as an easy-to-use tool to inform users about the safety of their push/pull scenario in order to help protect workers from disabling musculoskeletal disorders (MSDs).

The OSU SRI explains that in order to use the guidelines within the interface,

It will be necessary to enter several pieces of information about the push/pull task being tested into the online web interface in order to estimate biomechanical risk. This includes simple characteristics about the exertion such as the action being performed (1 Handed Pull, 2 Handed Pull, 2 Handed Push) and the exertion type (a straight push or pull or a turn). Practitioners will also need to measure maximum push/pull force required to move the object and the hand height from the ground (in inches).

The OSU SRI adds, “After entering all of the necessary information, the web interface will calculate the risk associated with performing that particular type of exertion and assign it a risk level of either green, yellow, or red.”

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.

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.

[1] Ohio State University. "Engineering a Safe Workplace," March, 23, 2015, accessed February 26, 2019, https://engineering.osu.edu/news/2015/03/engineering-safe-workplace/.

[2] The Ohio State University. "Engineering a Safe Workplace," March, 23, 2015, accessed February 26, 2019, https://engineering.osu.edu/news/2015/03/engineering-safe-workplace/.

[3] The Ohio State University. "An Objective Set of Guidelines for Pushing and Pulling," accessed February 26, 2019, https://ergonomics.osu.edu/guidelines/. All subsequent quotes come from this document.

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