by: Meryl B. Brutman, MPH
EDNF Board Member and Founder of Chicagoland Branch. Meryl has EDS type III. Reprinted from Loose Connections Volume XI, Number 4
This is the second of a three-part article on the recognition, evaluation, and control of potential risk factors and stressors that can lead to increased injury, discomfort, and/or fatigue. Part 1 introduced guidelines to recognize and evaluate each of the seven potential risk factors or stressors. Part 2, presented below, explores the variety of control methods available to reduce, eliminate, or avoid awkward postures, mechanical stress, and poorly fitting or poorly chosen gloves, in the home, workplace, and school. Part 3, to be presented in the next issue of Loose Connections, will discuss control methods for the remaining risk factors - repetitive motions, forceful exertions, vibration, and extreme temperatures.
Control measures can be divided into two main types: administrative and engineering controls. Some people add a debatable third type, Personal Protective Equipment (PPE), which includes back belts (technically abdominal belts) and other bracing/support systems. Administrative controls require someone's conscious decision. Examples are: increasing the frequency or duration of rest breaks, altering shift/break schedules, job (task) rotation, job enrichment or enlargement, exercise, and training.
Engineering controls usually involve redesign of the job, tool, or workspace and are built into the product or system. Little additional effort is required by users thereby increasing the likelihood the control measure will be effective. For this reason, engineering controls are preferred over both administrative and PPE controls. However, these controls are often very costly and time consuming to implement. It is not always feasible to design all potential risks and stressors out of every situation. In these cases, administrative controls can be quite effective. They can also be used as interim control measures while engineering plans are being implemented.
For ease of discussion, examples of general control measures for each risk factor will be discussed first. Please keep in mind there is no such thing as just a repetitive motion or forceful exertion control. Many of these control measures overlap. The ideal is to choose a method that eliminates or reduces as many risk factors as possible. Remember, creativity counts. It doesn't matter what the modification looks like as long as it accomplishes the goal of reducing risk. As an example, the task of assembling a desk often involves screwing nails into pieces of wood. This job contains several risk factors, including repetitive motions, awkward postures, forceful exertions, and mechanical stress. Yet, with one simple control measure - switching from a manual screwdriver to a powered one - all four of these risk factors can be reduced. But beware! Before making any modifications, weigh the pros and cons of switching methods or tools. Oftentimes, a control measure can actually add an additional stressor while eliminating or reducing other stressors. In the example above, switching to a power screwdriver reduces many risk factors. However, if the wrong tool is chosen, vibration can become a new risk factor. Of course, trading four risk factors for one is a pretty good deal. Just use your common sense. There are no right or wrong answers.
There are many simple, inexpensive ways to control awkward postures. They typically fall into three categories:
1) Change the orientation of work.
2) Change the work method.
3) Change, modify, or redesign the tool.
Oftentimes, control measures from all three of these categories are necessary. Let's start with a student writing on a desk, an employee typing on a computer, a parent cooking dinner, and an assembler gluing parts together. While these may seem like very diverse tasks, they all use work surfaces that may cause problems if they are not at the right height and oriented properly.
Different tasks require different workstation setups. However, they all have similar reference points. One of the most common reference points whether the task is done seated or standing is known as elbow height â€“ height of elbow from floor when elbow is in a neutral (90 degrees) position. This serves as a guideline to determine the height of the workstation. For instance, the majority of work is done 2-3 inches below elbow height. This includes tasks like writing, some computer work, stirring dinner, and light assembly. Thus, all of our examples above can use this guideline to setup their workstations. What if our assembler works on extremely small, delicate parts which require great precision? The guideline changes. Fine, precision work is usually done at or slightly above elbow height.
This helps support the elbow and forearm and allows for more precise work with less fatigue. Fine, but what about people whose jobs require a great deal of force, especially downward? Their guideline is 4-8 inches below elbow height and includes hammering, sawing, cutting, and some heavy assembling.
Now, we have a starting point for determining the height of the workstation. But how do we determine whether it is better to sit, stand, or a combination of both to perform our job tasks. (Not everyone will have a choice due to their physical condition). You guessed it. More guidelines. Remember, these are not set in stone, they just provide a good place to start. You also need to consider how you feel and be creative. There are always several ways to arrive at the same solution. For instance, if you are writing on a desk that is too high, you can either lower the desk or raise your chair. If neither of these is possible, some people would choose to write on their laps. While this is not an ideal situation, it is certainly better than writing on a desk that is too high, thereby causing very awkward shoulder postures.
Standing is usually preferred for precision work with supported elbows, light assembly work, and heavy work. Sitting is preferred for fine work, exacting visual tasks, writing or light assembly work, and moderate manual work. Note the overlap between sitting and standing guidelines. Several tasks can be done sitting or standing, depending on preferences. Rotating between sitting and standing tasks is often beneficial. Other tasks are better performed in more of a sit/stand posture. Ergonomically designed sit/stand chairs are readily available. They are especially good for tasks in the kitchen: sit/stand chairs take pressure off the back and feet, while allowing freedom of movement. Unfortunately, they tend to be rather pricey. A sit/stand chair capable of withstanding the rigors of kitchen work, costs at least $60. Here are some more guidelines to help in determining whether job should be done seated, standing, or in a sit/stand posture:
Sitting is usually less fatiguing than standing.
Seated people are better able to perform precision tasks.
Standing allows the person to exert greater forces.
Standing allows greater freedom of movement.
Muscular stress in increased for people who stand.
If you must stand, try to alternate with a seated task.
After choosing the correct height for the task, deciding whether to sit, stand, or sit/stand, the rest of the workstation must be set up properly to avoid awkward postures. First, determine your reach envelope - the reaching distance your body can handle without putting it in awkward positions. While seated or standing erect, not hunched over, with elbow extended out front (about 180 degrees), but close to the body, note your maximum reach within a semicircle without overextending your elbow or reaching forward. Start on the left side of the workstation and sweep your arm in a semicircle until you reach the right side. This space encompasses your reach envelope. Place frequently used items in this area.
One great way to limit awkward postures is by eliminating the temptation to do so. What does that mean? If you know what items are used frequently, do not place them in a position where you must constantly reach overhead, behind your body, down to retrieve items from the floor, or twist. People who keep frequently used reference books on an overhead shelf, inevitably end up over reaching/stretching for the book instead of standing up to retrieve it. Thus, by properly arranging workstations for particular tasks, temptation is avoided. If several people share the workstation or if several different tasks occur there, adjustable items are imperative to ensure that each person doing each task can set up their workstations properly.
Recall from Part 1 of this article the uniqueness of static postures. These occur when a body part is not moving, but the muscles must still work. Avoid using hands as holders or jigs. Do not hold an item in the left hand and use the right hand to work on that item. This puts a tremendous amount of stress on the left, non-moving hand. Instead, use a vice grip, holder, or jig to position and hold the item in place. It doesn't need to be fancy and you don't need to spend a fortune. Most people already own materials that can be used for this purpose.
Another way to control awkward postures is to change work methods. Have someone observe you do a task that causes discomfort or unusual fatigue. If possible, videotape the job or at least take still pictures. The reasoning behind this is simple - most of us do not realize how we look when we perform various tasks. We may believe we are doing things correctly, when in fact our bodies often deceive us.
Now analyze the videotape or pictures. Look for the seven potential risk factors or stressors discussed in Part 1 of this article. Focus on the most severe risk factors first. Ask yourself if you are doing the job in the best possible manner, with the least amount of stress to your joints and soft tissues. Are your joints in neutral positions? Do you employ any extreme ranges of motion? Are you lifting properly? Knees should be bent, not straight, although many people still insist on lifting with their legs straight even after back lifting training. Why is this? Because straight leg lifting requires less energy than bent knee lifting. So a person with a repetitive lifting task is more likely to lift with straight legs to conserve energy. Here, as in many other ergonomic examples, there is a trade-off and no perfect solution. However, since our goal is to reduce the amount of awkward postures and the severity of each one, it is clear that bent leg lifting is preferable.
Lastly, another very effective way to control awkward postures is to choose the proper tool. First, consider whether the work will be done on a horizontal or a vertical area. Unless the tool is adjustable, you cannot use the same one on both surfaces without causing significant awkward postures to the upper extremity. Say you have a pistol shaped drill. In order to maintain neutral postures, it should be used at or close to elbow height on a vertical surface, although there are a few exceptions. If you were to use this tool on a horizontal surface, your wrist would be forced into a very awkward posture, most likely ulnar deviation. Thus, as a general guideline, power grip tools work best on vertical surfaces and in-line (straight handle) tools work best on horizontal surfaces. Here are some other general guidelines to consider when choosing tools. Recall that an ergonomic tool used in an incorrect manner is just as potentially risky as using a non-ergonomic tool.
Choose A Tool So That
Hands, wrists, arms, and shoulders can be kept in neutral positions.
The tool can be held near its center of gravity to reduce the amount of force needed.
The weight is as light as possible. Don't use a heavier tool than is necessary.
You can use a power or oblique grasp. Avoid tools that require pinch grips.
Handles are well padded and long enough to distribute force over entire palm.
Trigger mechanisms are operated with more than one finger & don't require continuous pressure.
It has built in vibration dampening features.
It is easy to open and close without effort. Buy tools that are spring-loaded.
To summarize, there are 3 major methods to control awkward postures. They are as follows:
Change Orientation of Work
Place frequently used items within easy reach.
Orient bins at an angle.
Use jigs/holders to reposition work.
Provide adjustable workstations. Ensure work height is correct for the task.
Change Work Method
Bent vs. straight-leg lifting.
Training. Proper postures/joint positions.
AVOID extreme ranges of motion.
Change, Modify or Redesign Tool
In-line vs. pistol grip tool.
Ergonomic vs. non-ergonomic tool.
Use spring-loaded tool whenever possible.
Mechanical Stress Controls
Mechanical Stress is one of the easiest risk factors to control. Any sharp edge which comes into contact with a body part should be rounded or padded. Likewise, any tool that digs into your hands or has sharp edges should be padded. There is an abundance of material that makes great padding or you can buy tools and accessories that are ergonomically designed to distribute force over a large surface area.
Many packages come with foam padding. Cut it to the proper size and use tape to stabilize it and you have a cheap and effective control. Since foam is easily compressed, start with a larger amount. Replace worn padding as necessary. Towels can also be used. Be creative. If you need something that looks a bit more professional, there is a wide range of products on the market. These include wrist and mouse rests which come in a variety of sizes and different types of material, elbow sleeves with padding, cut resistant, cushioned gloves and tools, and ergonomically designed scissors, pliers, etc. that distribute force evenly over the entire hand. Proper workstation setup can also decrease mechanical stress. Avoid using hands as tools, especially hammers. Do not pound items with hands. Control measures for Mechanical Stress are summarized below:
Round or flare sharp edges and objects.
Pad sharp edges and objects.
Distribute force over as large an area as possible.
Ensure workstation is at the correct height and setup properly.
Don't use your hands like hammers or any other tools.
Poorly Fitting or Poorly Chosen Glove Controls
Believe it or not, many people who wear gloves, especially in the workplace, have no idea why. When asked, they state that the person before them wore gloves, so they do too. Bad answer. It is imperative to know why you are wearing gloves. Why? Because poorly fitting or poorly chosen gloves are a potential risk factor. If you don't need gloves, you shouldn't be wearing them. The next step is to determine why gloves are necessary. Ask yourself the following questions: Am I trying to protect my hands from the cold, cuts, burns, chemicals, vibration, infection, food handling, or mechanical stress? Do I need dexterity or to feel sensation in my fingers for this task? Am I handling delicate objects? Will my hands get wet? Once you know why, it's time to choose the right type of glove.
Rule #1 - Choose the least bulky glove available that will do the job and protect your hands. If you are only concerned about cuts on the fingers, consider using finger tape only. If it is your palm that is exposed and nothing else, consider using an anti-vibration glove with the fingers tips cut out.
Rule #2 - Make sure the gloves fit correctly. If it doesn't fit, you must acquit. Oops. I got a bit sidetracked. There is no such thing as one size fits all. Well, there is, but I think you can guess how I feel about that. Glove manufacturers are finally responding to the need for odd sizes, both very small and very large so there should be no excuses. Almost every size is available off the shelf.
Rule #3 - Choose the type of glove carefully and thoughtfully. Throw away worn, torn, or holey gloves promptly. Gloves are extremely specialized today. If you are allergic to latex, make sure there is none in your glove. If you like the powder that comes in some of the gloves, great, but keep in mind that people may be allergic to that too. If you need good sensitivity, make sure the gloves are extremely thin and form fitting. If you need dexterity or are afraid of dropping things, get gloves with gripping dots. Afraid of cutting off your finger? Then, you need cut-resistant gloves made of Kevlar and other high tech materials. Do you frequently dip your arms into vats of poisonous, hair burning chemicals? Make sure the glove material is made for the type of chemical you use.
Analyze the need for gloves. Why are you wearing them?
Provide a variety of styles and sizes of gloves. No one size fits all.
Eliminate or reduce the need for gloves.
Use the lightest, least bulky gloves possible.
Three risk factor control methods down. Four to go. As you can see there are many ways to reduce, eliminate, or avoid these three potential risk factors or stressors. Although this was not intended to be an exclusive list (it would be impossible), it does cover many of the main control methods. Remember, it is impossible to eliminate all risks. Focus on the most severe & reduce others as much as possible.
I have put together a list of adaptive equipment/ergonomic catalogs that carry the products mentioned in this article. If you would like a copy, please send me a business size SASE. I strongly suggest that you request as many catalogs as possible. Not only is there a wide range of similar products, there is also a wide range of prices, return policies and guarantees. Comparison shopping is a must. Many drug stores, large chains, and discount outlets also carry adaptive equipment and assistive devices. New Products are introduced every day.
U.S. Department of Labor, Occupational Safety and Health Administration, Ergonomics: The Study of Work, 1991, pp. 1-19.
Vern Putz-Anderson, Cumulative Trauma Disorders: A Manual for Musculoskeletal Diseases of the Upper Limbs, 1988, Taylor & Francis, pp. 1-25.
Eastman Kodak Co. (1983) Ergonomic Design for People at Work, Vol. 1, Lifetime Learning Publications.