The Bottom Line: Pushing or Pulling? That is the Question
Posted on July 12, 2022 | in Ergonomics
VelocityEHS ergonomist, Blake McGowan explains the latest ergonomic research on pushing and pulling at work.
Hi, my name is Blake McGowan, and I’m a certified professional ergonomist with Humantech (now VelocityEHS Ergonomics).
Now, one of the most common tasks within the industry is manually pushing and pulling carts, but unfortunately, it doesn’t seem to get the same research attention as manually lifting and lowering materials. More recently, people have started to notice that individuals are pushing and pulling carts more frequently than they’re actually lifting and lowering materials.
So, what does this mean? What do health and safety professionals need to know?
Well, in 2014, a group of researchers, including Garg, Waters, Capellash, and Kawasaki, put together a comprehensive review of manually pushing and pulling carts.
So, what did they find?
First, they showed that there’s an association between pushing and pulling carts and discomfort in the shoulders and low back.
Second, the linkage between pushing and pulling carts and shoulder disorders and low back disorders really isn’t studied that often, and the evidence is fairly weak, so a lot more research is needed.
Third, the 1991 Liberty Mutual tables for push-pull forces are still a valid tool and are probably the best tool available for practitioners.
Fourth, it is unclear if it’s better to push a cart or to pull a cart. More research is needed to determine.
Fifth, it is unclear what the appropriate or optimal handle height is for pushing and pulling. We still need to figure out what the optimal handle height is to minimize shoulder forces as well as low back forces, but it probably lies somewhere between the waist and the shoulders.
And last, some new regression models have been developed that help us determine the acceptable push-pull forces for different handle heights, push differences distances, as well as frequency, allowing us to gather more specific data.
So, what does all this mean? What’s the bottom line?
Well, the bottom line is that the 1991 Liberty Mutual tables for push-pull forces are still valid, and they’re still the best tool available for practitioners.
Thanks, have a great day!