Repetitive Motion Controls

The ideal control measure for highly repetitive tasks is automation. Unfortunately, many jobs cannot be automated due to monetary or technological limitations. Household tasks and hobbies by nature are usually repetitive and difficult, if not impossible, to automate. In these situations, administrative controls can be very effective. The more repetitive the task, the more rest breaks should be taken. These do not have to be more than a few minutes. When typing at the computer or writing, take breaks at least every 30 minutes. (If you tend to get completely absorbed in your work and lose track of time, you may want to set an alarm clock to remind you). Use this time to stretch, change positions, and focus your eyes on an object at least 20 feet away for at least 20 seconds (20/20 rule). If your body is protesting and doesn't want to type anymore, try switching to an alternate task which uses different muscle groups. For example, returning phone calls, talking to a colleague or coworker, running (driving, walking, power or manual wheelchair) errands, doing laundry or some other light housework. If you are completely fatigued, do not push yourself. Take a longer break and consider taking a nap.

Another effective control measure for repetition is called job enlargement or enrichment. This concept is similar to job rotation and involves making the task larger. Thus, instead of sewing the same stitch on the same part of clothing for several hours, a group of people will sew an entire garment. Likewise, in the automotive industry, employees used to work at the same task all the time. Not only was the job monotonous, but it overworked the same muscle groups day after day. Now, several manufacturers use job enrichment and allow a team of workers to assemble an entire car. Each person in the team gets to do every task. I know what you are thinking!! I'm not a seamstress in a factory or an automotive worker on an assembly line, so this doesn't apply to me. That may be so, but many people have similar setups in their own homes, doing their own tasks.

Let’s say you are planning an EDS support group meeting and want to send letters to EDSers, Doctors, and Hospitals in your region. You have a mailing list of 100 people and organizations. Each envelope must contain a two page letter folded in thirds and stapled. They must be in the mail the next day or else... Nobody is around to help, so you must do it yourself. First, ask yourself if 2 pages are really necessary? Can I get my message across with fewer words? How about using the other side? The next task is to try to rearrange the job, so less work is required. Organize the task to avoid excess motions. Ensure that objects are easy to reach. Set up an ergonomic workstation. (See Awkward Posture Controls in the last issue of Loose Connections for more details) Now you are ready to begin your task. Many people would choose to address all the envelopes first, staple all the letters, fold all the letters, and finally stuff all the envelopes. In essence, one task is done repetitively for an extended period of time before switching to another repetitive task. Much like a seamstress who uses one stitch on one type of garment. To lessen the repetitiveness on the same tendons, ligaments, etc. vary the job. Don't do all the folding in one sitting without doing other tasks.

Are there other ways to lessen the stressors? Yes. A great deal of technology exists to make this job easier. For most people, money could be a limiting factor. If you were lucky enough to win the lottery, (miracles do happen), you could pay someone to do the work. Or, if you would like to do it yourself, make things easier by obtaining/using an electric stapler, an automatic folding machine, a computer, software to make labels, a printer, etc. Even using only one of these items will significantly reduce the amount of repetition. As one of the most common stressors, repetitive motions are usually impossible to avoid. Fortunately, they are relatively easy and inexpensive to control. The bullet points below summarize the control methods discussed above and provide general concepts used to reduce the risk of repetitive motions.

Enlarge/Enrich Job.
Rest/Break Schedules. More repetition means more breaks are needed.
Reduce Amount Done at One Time.
Power Tools instead of Manual Tools. Electric Stapler. Automatic Folding Machine. Powered Screwdriver.
Rotate to Tasks with Different Risk Factors.
Use Ergonomic Tools and Assistive Devices.
Reduce or Eliminate other Risk Factors.
Forceful Exertion Controls

Reducing the amount of force necessary to perform a particular task is not as difficult as it may seem. Many different control methods are available. A good place to start is with modifying bad habits. If you like to take frustration out on keyboards, you are only hurting yourself. Newer keyboards are designed with good, tactile, feedback, so it only takes a few ounces of force to depress the keys. If you use more than that, you are increasing the amount of force used to a potentially unhealthy level. So don't bang on keyboards. If you have a very old keyboard or one that had its share of drinks spilled on it, you may find it increasingly difficult to operate. This may be the time to consider purchasing a new keyboard. There are many types to choose from ranging in price from, about $30 for a standard keyboard to $750 for a completely adjustable split keyboard that allows a wide range of postures.

Many forceful control measures overlap with those of the other potential risk factors. Still others are just common sense. For example, always use the lightest possible tool that can do the job properly. If the tool is very heavy, try using an articulating arm, balancer, or jig. Articulating arms are adjustable and significantly lessen the amount of force necessary to use the tool. Purchase spring-loaded tools whenever possible. They require much less effort to operate. Ensure all tools are maintained properly and that blades are kept sharp. It's amazing how many people use dull knives and cutting tools and don't realize how much extra force is required. Having difficulty opening bottles and jars? Many people with arthritis, including people with EDS, have trouble with this type of task. For those who just need some minor assistance, increasing the friction between your hand and the lid usually works just fine. I'm sure many of you already use those rubber, grippy things. While they are quite effective, many people simply need more help. The next step is to purchase an easily adjustable manual jar opener with an easy grip handle. They provide excellent leverage while still allowing a person to use their own muscles. If hands are very weak or have nerve damage, it may be necessary to use a powered jar opener in conjunction with some type of holding device.

For those of you students out there, writing can be a very forceful exertion and quite painful and debilitating. Pens and pencils are relatively thin and require a pinch grip to hold, so right away you're at a disadvantage. If the pen doesn't write smoothly, even more force will be required. Fortunately, you can purchase items to make the pens thicker and easy to grip. Many pens now have built in soft grips or have much larger circumferences to make them easier to hold. Good quality pens can roll across the paper without too much effort. The ink flows smoothly and easily. For some people, writing may still be difficult. Typing is easier on some people and can provide an alternative. Recording lectures is yet another option.

Opening doors with keys can be quite challenging, even to healthy people. It requires a pinch grip, while at the same time, the wrist is in an awkward posture. Key holders are an inexpensive solution. They are easy to grip and provide leverage to open doors with little effort. If you still need more assistance, electronic/remote systems are available. To summarize forceful exertion control methods:

Reduce Weight of Tools or Parts. Use Balancers, Articulating Arms, Jigs. Choose spring-loaded tools.
Maintain tools properly; keep all blades sharp.
Use Power Tools whenever possible.
Reduce Torque.
Increase Friction of surfaces.
Distribute forces over as wide an area as possible.
Use Power Grip instead of Pinch Grip.
Use Large muscles instead of small ones.
Vibration Controls

In the past, few manufacturers paid much attention to the potential health effects of vibration exposure from their products. Today, there is a wide range of tools and products that are specifically designed to reduce the amount of vibration. Many have built in vibration protection or dampening qualities. If budget is a concern and newer anti-vibration tools are not an option, other methods are available to minimize vibration exposure.

If possible, vibration should be controlled at the source first. Good maintenance of tools and engines is a good start. Most newer trucks have air ride seats which helps to minimize vibration exposure to the driver. Dampening materials and anti-vibration covers and wraps are inexpensive and provide a layer of protection. In addition, these materials also make it easier to grip the tools, thus providing some forceful exertion control as well.

If vibration covers aren't available, can't be used for some reason, or don't provide enough protection, anti-vibration gloves can be worn. These are similar to weight lifting and bicycle gloves and usually have ample padding in the palm. They come with and without finger protection. Many people prefer having their fingers uncovered to get a better grip or feeling. While this can help reduce the amount of force used, it does not adequately protect the fingers from vibration. Recall that fingers are one of the most sensitive body parts with respect to vibration.

Each body part has its own resonance frequency. If a tool happens to be at the same frequency, there is a greater potential for discomfort or injury. Without getting into the complexities of characterizing vibration, here is a story which demonstrates the danger of resonant frequencies. Most people consider bridges to be stable and stationary, but they do sway and move. There was a time when this movement was not factored into bridge construction. Thus, if something caused the bridge to sway at a certain resonance frequency, the entire bridge could collapse. One day a group of soldiers marching in perfect unison started across the bridge. Before long, the bridge started swaying wildly and eventually collapsed. Today, soldiers and marching bands are taught to march out of step on bridges to prevent a possible catastrophe, even though engineers now factor resonance frequencies into their bridge designs. Vibration control methods are summarized below.

Maintain tools in good working condition.
Use Balancers, isolators, and dampening materials.
Use Vibration covers/wraps.
Avoid operating tools at resonance frequencies.
Use anti-vibration gloves.
Eliminate use of high vibration tools.
Choose anti-vibration tools.
Extreme Temperature Controls

Cold exposure usually comes from 2 different sources. The temperature/weather is the most common cause of cold, but it can also occur when power tools are not properly maintained and cold air leaks onto the operator's hands. Dressing appropriately for the outside or inside temperature can lessen the impact of cold exposure. There are many new fabrics on the market that are extremely lightweight, yet provide superior warmth protection. These are ideal for people who need to move around and use their extremities, but cannot afford to be bundled up to the point they lose joint range of motion. If a power tool is causing the cold exposure, maintenance should be informed immediately and the tool taken out of service until it is repaired. If this is not practical, protect the person's hands from the exhaust as much as possible. Gloves can be used or the leaky air can be diverted away from the hands or blocked somewhat with tape, tool wraps, cloth, etc. Just ensure the tool can still function properly and the modifications don't cause other problems, such as creating pinch points or the cloth getting caught in the tool.

Heat exposure is common in many industries, schools and homes where there is inadequate air circulation, air conditioning doesn't operate properly or is often broken, or no air conditioning exists at all. Many plants can easily reach over 120 degrees inside. Cooking over a hot stove all day can also cause significant heat exposure. In these situations, especially when combined with humid conditions, water should be readily available and people should take more frequent rest/cool breaks. In some offices, plants, and homes, there may be a cool room where people can go during breaks. Since this is not always practical, other measures must be taken to keep people cool. The cheapest and easiest way to stay cool is to place a cool, wet, bandanna around your neck or forehead. You can even purchase special bandannas that have built-in cooling crystals to keep the water cool for up to 2 full days.

When working in really extreme heat and high humidity, cooling bandannas, more frequent rest breaks, and a constant supply of cold water may not be sufficient enough to keep people from falling prey to heat cramps, exhaustion, or even heat stroke. It may be necessary to wait until the area cools down to work. Another solution would involve wearing a cooling vest.

While they are quite effective in keeping people comfortable temperature-wise, they are heavy and cumbersome to wear and are probably not appropriate for most people with Ehlers–Danlos Syndrome (EDS). Extreme temperature controls are summarized below:

Eliminate cold exhaust air leaks from power tools.
Provide fluid and increased rest breaks in extreme heat.
Provide proper personal protective equipment (PPE).
Cooling Bandannas and Vests.
Proper clothing and choice of gloves.

Wow. We made it. As you can see there are many ways to reduce, eliminate, or avoid potential risk factors or stressors in the home, workplace, and at school. There is an infinite amount of control measures limited only by one's imagination. While it is impossible to eliminate all risk factors and stressors, we should strive to reduce as many of them as possible within financial and technological limitations and constraints.

Ergonomics is a multidisciplinary science that is gaining in popularity at a rapid pace. More and more products are claiming they are ergonomically correct or designed ergonomically. This three part series was meant to serve as an introduction to this fascinating (okay, so I'm biased) subject. Needless to say, I had a very difficult time deciding what topics should be covered and in how much depth. Usually, I present this type of material in person so that I can perform demonstrations and introduce some ergonomic products. With the blessing of the EDNF Board, I do plan on giving this lecture in person at one of the upcoming educational seminars held during our national conferences (to be announced at a future date), but I didn't want to wait to provide you with this valuable information. Thus, I chose to begin with the basics and providing a general overview of the risk factors and some possible control measures. Some of you may have found these articles too general or too scientific, too basic or too advanced, or perhaps missing certain topics you would like to have seen discussed.

I urge you to let me know (via the EDNF office) what ergonomic topics interest you. What subjects, if any, would you like to see covered in more detail? Do you have any specific questions, concerns, or problems you would like to see answered by an ergonomist? I welcome all your feedback including constructive criticism. In the future, if there is enough interest, I would be happy to write additional ergonomic articles based on your responses and requests. I hope you were all able to learn something new from this 3 part series on ergonomics.

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.

Thomas J. Armstrong, "Ergonomics and Cumulative Trauma Disorders", Hand Clinics, Vol. 2, No. 3, August 1986, pp. 553-565.

U.S. Department of Labor, Occupational Safety and Health Administration, Ergonomics Program Management Guidelines for Meatpacking Plants, 1990, pp. 1-10.

Stephan Konz, Work Design: Industrial Ergonomics, 1990, Publishing Horizons, Inc., pp. 109-509.

Eastman Kodak Co. (1983) Ergonomic Design for People at Work, Vol. 1, Lifetime Learning Publications