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Identifying The Ergonomic Risk Factors Of A Job: The Eighth In A Series Of Useful Information ‘That You Can Use’ From The Center For Occupational & Environmental Medicine At Buffalo’s Erie County Medical Center

Published Monday, March 12, 2018
by Nellie J. Brown, MS, CIH/Via The COEM @ ECMC
Identifying The Ergonomic Risk Factors Of A Job: The Eighth In A Series Of Useful Information ‘That You Can Use’ From The Center For Occupational & Environmental Medicine At Buffalo’s Erie County Medical Center Editor’s Note: The Center for Occupational & Environmental Medicine (COEM), located at Buffalo’s Erie County Medical Center (ECMC), is available to Workers both Union and non, providing care to those who are injured, impaired or who develop an illness as a result of workplace factors - which may include exposure issues, physical injuries, or any other job hazard.  The COEM is also a New York State Department of Health-funded Clinic for the diagnosis and treatment of occupational injuries and illnesses for Workers living in the five counties of Western New York.  The COEM also offers services for any Worker with other job-related medical needs, such as physicals required for employment or licensure - and they assist with completion of paper work for Worker Compensation Claims. With state-of-the-art diagnostic equipment and a highly-skilled and caring Staff, the COEM’s Health Care Services meet U.S. Occupational Safety & Health Administration (OSHA), U.S. Environmental Protection Agency (EPA) and Department of Health Safety Standards.  The COEM takes a different approach to the treatment of injured Workers through prevention, early diagnosis and treatment.  Opened in 2015, the COEM was developed with great support from Western New York Labor Unions and their Leadership.  The COEM, which is open Monday through Friday - 9 a.m. through 5 p.m., can be reached at 716-898-5858.

The author of this article is Nellie Brown (pictured below), who serves as the Director of the Workplace Health and Safety Program, a Statewide Program of the Worker Institute at Cornell University’s School of Industrial and Labor Relations.  Nellie provides Industrial Hygiene Services for the COEM.

Tony uses a huge wrench to reach large bolts located overhead, extending his arms above his shoulders and pushing hard on the wrench.  But after few months of frequently repeating this task, it led to a rotator cuff injury requiring surgery.  And over at Mark’s workplace, a few times a year, a major client needs a delivery right away.  Every department supplies people to help load the truck.  Working quickly, Mark was swinging each box from the floor, giving it a boost upward with his knee to grab it better.  Mark felt a sharp twinge in his back, but kept on going.  Later that evening, he could hardly move.  He was in considerable pain with a back spasm.  His wife called an ambulance.  With muscle relaxers and pain medication, he walked out of the emergency room hours later with a recommendation for physical therapy.

Tony and Mark both experienced musculoskeletal injuries - over-exertions of muscles and joints.  Workers trigger these injuries by a direct trauma (such as a slip or fall).  Mark’s injury was a single overexertion from a task done infrequently.  Tony’s injury was a cumulative trauma, the result of a repetitive task and developing over time.

The common symptoms of overexertion of muscles and joints include soreness, pain, discomfort, redness and swelling, limited range of motion, stiffness in joints, weakness and clumsiness, numbing/ tingling sensations (“pins and needles”), popping and cracking noises in the joints, and “burning” sensations in muscles.

These are warnings and we should act quickly to prevent further damage.

At first, our symptoms of pain and/or weakness are felt during work and disappear during off-hours or rest.  Usually the body recovers and the problem is completely reversible at this stage.  But if the workplace conditions of the task are not changed and the injury progresses, our symptoms may no longer disappear completely between work shifts.  Our bodies are unable to completely repair the affected tissues during rest and the symptoms begin to interfere with performing our usual work activities.  We might find that we are moving more slowly, taking care how we bend or reach, conserving our movements just to get through the day.  But, if the work conditions are still not changed and the trauma is allowed to continue, we may find that the pain persists while at rest - we may even have trouble sleeping.  Severe pain, limited mobility, loss of sensation or muscle weakness can make it impossible to perform most tasks.  Brushing teeth, combing hair, picking up objects, getting up and down on the toilet - everyday life is impacted.

The majority of workplace back disorders are due to repetitive strain and its associated insufficient healing.  Also, keep in mind that cumulative trauma can be aggravated by the slower rate of healing that is typical with aging.

Reporting injuries at the earliest stage enables the job to be evaluated for risk factors.  So, to get started, what should we be looking for?  We begin by observing ergonomic risk factors.  What is the body actually doing while we perform a job or task?  Are any of your joints in a non-neutral position?  If you imagine yourself standing, relaxed, with your arms at your sides - this is considered a neutral position for the body.  The further our joints are from this neutral position, the more the supporting muscles are stretched.  The joint is not well supported, making it weaker and easier to injure.  In Tony’s case, loosening or tightening the nut with his arms extended above his shoulders puts his shoulder joints in a weak position.  Pushing hard on the wrench puts his shoulder joints at considerable risk of injury.  How could we keep the joints in a more neutral position?  We look at a job and see where any part or parts of the body are not neutral and move the body or use ergonomically-designed tools which put the bend in the tool (rather than bent joints in the user).  In Tony’s case, a stable platform could be placed at the machine to raise him so that he could hold the wrench at waist height and lean into the wrench with his body weight.  This lowers his arms and relocates the task in a position of strength for his body.

We also need to ask whether the work or load is too far out from the body.  The further away it is, the more our back muscles tighten to support us - squeezing down on the disks in the spine. How could we reduce this risky position?  For any lifting job, we need to bring the load close.  It is especially helpful to keep lifts between shoulder and knee height - avoiding lifts from the ground or above the shoulders.  Even a squat lift can be problematic if the load cannot be brought close because it is too wide to fit between the knees.  For wide items, we should eliminate lifts below knee-height by putting the item on a few stacked pallets or a lift table.

Does the job require that the body be bent forward?  This is similar to the previous risk factor because, when we bend forward, the upper body is suspended from the lower back.  The surrounding muscles are stretched and weaker, thus becoming easier to injure.  Rounding the back places considerable pressure on the disks in the spine.  How can we reduce this risky position?  If we’re lifting something, we should use a squat position rather than a bent back.  If we are bending over a work surface, we could raise the height of the task, stand on a platform or tilt the work surface.

Now, is the trunk of your body twisting?  If so, this really screws up your back.  Even worse is combining lifting and twisting.  Avoid any twisting.  If lifting and carrying an object, lift while facing forward and then take steps with your feet to turn your body and face toward a different direction.  If rushed to get a job done or to match the speed of a machine, we may feel that twisting is helping us to work faster - but taking a few steps with the feet is far safer

Is your body making sudden movements?  Swinging the limbs or swinging a lifted weight can be very dangerous.  Swinging forces muscles to stretch faster than they are able to respond, producing over-stretching or even tearing of muscles or tendons.  Swinging something is often the way someone will lift a heavier-than-usual object - sometimes to put the item onto the hip or shoulder.  In Mark’s case, with a limited time to load the truck, he began swinging the box from the floor, giving it a boost upward with his knee to bump it up higher and get a better grasp of it. But the sudden forces on his back strained his muscles, producing the spasm.  Avoid swinging motions and lift as smoothly as possible.  If an item is too heavy to lift alone, get help or use a machine.

For how long a time can the body hold a posture or repeating a movement?  When we hold the body in one position for a long time, the tight muscles clamp down on the blood vessels that supply them with oxygen and food and carry away waste products.  Over time, this is damaging to tissues.  A similar problem, called contact stress, involves prolonged pressing or leaning the body, hands, or wrists against a hard or sharp edge like the end of a table or the handle of a tool. Prolonged repetitive movements are also damaging to tissues.  Recent research shows repetitiveness can actually damage tissue gradually, causing inflammation, and even bone loss, as injury accumulates.  How can we reduce this effect of time on static positions or on repetitiveness?  We need to move around and change position - not just sitting or standing all the time.  We need breaks and recovery/rest periods.  Job rotation can help by dividing the risky task among several people.  We can put padding on sharp edges or change tool handle shapes from multi-sided to round with knurling.  For standing jobs, gel mats on the floor and sit-stands can help.

Does the task overwork a few muscles, producing localized muscle fatigue?  Sometimes a job or task involves using just a few muscles, but working them a lot.  Some examples could include keyboarding, assembly line work, digging a hole with a shovel, re-shelving books or packaging products for shipment.  How can we avoid overworking a group of muscles?  We could change position frequently, alternate sitting and standing or take breaks to reduce fatigue.  You also need to ask is your equipment is up-to-date?  Modern equipment may have designs producing better positions for the joints and back.

You also need to ask whether your body is being worked to the point of exhaustion.  Fatigue, like hunger and thirst, is a warning - our body is saying we have reached our limit.  Tired muscles build up waste products.  Once exhaustion occurs, muscle injury is more likely.  Also, when we become exhausted - yet must continue working, we will simply get work done any way we can and often swing a lifted object, twisting the back in the process - anything to keep on going, which further increases the risk of injury.  This was Mark’s problem as he became tired and began lifting and swinging the boxes just to get the job done.  

How do we put limits to prevent exhaustion?  Our work hours and scheduling need to include breaks and recovery/rest periods and we need to keep our muscles hydrated by drinking enough water.  Usually, frequent short rest periods reduce our fatigue better than a few long breaks with long work intervals between them.  It is especially risky to work through breaks so that you can go home early, but exhausted.  Over time, this can take a heavy toll on the body.  This risk factor may also be reduced by dividing the tasks among several people to reduce the fatigue of any one person.  It also helps to vary your tasks as this uses different postures and muscles - along the lines of the idea that “change is as good as a rest.”  Mark’s employer needs to redesign the loading job - planning ahead for the unusual staffing needs and making sure that lift tables, carts, and other moving equipment are available.  Also, that people know how to lift properly and that the amount of time allotted for this job is reasonable, not rushed.

We also need to ask ourselves whether our bodies are being exposed to vibration?  We could be using vibrating tools, handling vibrating machine controls or sitting on vibrating equipment - such as a truck or forklift.  Prolonged vibration can produce damage to nerves and blood vessels in the hands (Raynaud’s Syndrome), or the back.  How do we reduce or avoid vibration?  Some new equipment designs have been able to damp out most or all vibration.  There are padded or gel-filled gloves for vibrating tools or machine controls.  Good seat cushions and a proper seat shape with lumbar support can help to protect the lower back.  And work scheduling needs to include breaks and recovery/rest periods to vary the posture and muscles used and break up the intervals of vibration exposure.

While we’ve been exploring these risk factors individually, the interaction of these factors has been shown to increase risk dramatically.  The damage from the force used by our bodies - to grip tools, lift objects, push/pull items - can be multiplied by repetition, non-neutral postures and/or vibration.

Simple, direct observations of a job can go a long way toward identifying problems so that they can be reduced or eliminated.

Often the best ideas come from the shop floor as we learn to recognize these risk factors and propose solutions.



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