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In an
effort to minimize the astounding number of back injuries each year
resulting from lifting in manual material handling (MMH), many lifting
duties have been replaced with pushing or pulling. While this does take
much of the pressure off the back, experts are surprised to discover
that pushing and pulling also places the low back at risk in other
ways. In fact, low back injuries from pushing and pulling account for
about 20% of reported work injuries. How is the low back still so
vulnerable when pushing and pulling, and what is the next step to
resolve these injuries?
What’s
The Problem?
When the
back muscles are used in lifting, they’re recruited for stabilization,
movement, and force. The actual movement taking place is extension of
the spine – as in straightening the back after bending forward. When
weight is carried through extension of the spine, the low back bears
the weight of the object as do the arms. Pushing and pulling don’t
require extension of the spine. However, it does usually force flexion
of the spine – bending forward as in touching your toes. When the spine
is in flexion, the low back muscles are still needed for stabilization
and force. As it turns out, spinal compression is actually greater
during flexion than it is during extension. So the back is vulnerable
to injury in a new, albeit unexpected, way during pushing and pulling
tasks.
How
Do We Fix It?
As
successful as it was to reduce the number of back injuries by replacing
lifting, these muscle traumas can be very debilitating. Creating a new
means to injure the back really doesn’t solve the problem. Some
companies have already invested in pushing and pulling solutions and
can’t completely change everything again. There are important measures
one can take to make his current pushing/pulling task safer.
- Assess grip to the floor:
this goes for both the employee moving the object and the cart itself.
Are the worker’s shoes gripping to the floor or slipping around? How
easily do the wheels turn? Is the handle loose? Does the cart turn
easily? Ensuring that the employee has solid contact points and isn’t
moving something too heavy to maneuver will create better posture to
push or pull.
- Assess the height of the
handle: the handle on the cart (or pallet jack, etc.) should allow the
employee to push/pull without bending forward. This will be different
for everyone.
- Assess the angle in which the
employee’s body needs to be to move the cart: this seems like a
no-brainer based on the previous two points, but weight, size of the
object, and a variety of other factors determine whether a person can
remain standing straight when pushing or pulling an object. Pay
attention to the demands placed on the body.
- Implement motorized carts:
removing the need to both lift and push or pull is ideal. The entire
process of lifting and transporting can be automated or motorized. This
is safest for employees as far as musculoskeletal disorders (MSDs) go.
If making the change to automation isn’t feasible right now, taking
action to make pushing and pulling as safe as possible will be a great
start.
As with
any ergonomic concern, there are a variety of steps to take in order to
make a workstation it’s very safest. Consult the expert that is right
for you to evaluate your options to minimize MSDs in manual material
handling.
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