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Principles of Ergonomics in the Workplace

Principles of Ergonomics in the Workplace

Posted by Uncaged Ergonomics on 29th Dec 2017

Ergonomics is the science of properly fitting the workspace to the worker, and maximizing the layout and available tools to create efficiency and productivity. Integration of computers in the workplace, one size fits all office furniture, and the demand for higher productivity and longer work hours results in the adaptation of poor work postures and the performance of repetitive tasks in those sustained poor postures.

Work in Neutral Postures

Your posture provides a good starting point for evaluating the tasks that you do. The best positions in which to work are those that keep the body in neutral positions.

Maintain the S-curve of the spine


Your spinal column is shaped roughly like an S. It is important to maintain the natural S-curve of the back, whether sitting or standing. Working for long periods with your back in a C-curve, such as sitting at a typical office desk, can place strain on your back. Good lumbar support is often helpful to maintain the proper curve in the small of your back. The inverted V-curve creates an even greater strain on your back. Even without lifting a load, bending over like this creates a great deal of pressure on the spine.

Keep the neck aligned

The neck bones are part of the spinal column and thus are subject to the same requirements of maintaining the S-curve. Prolonged twisted or bent postures of the neck can be as stressful as the lower back. The best way to make changes is usually to adjust equipment so that your neck is in its neutral posture.

Keep elbows at sides

The neutral posture for your arms is to keep you elbows at your sides and your shoulders relaxed. This is pretty obvious once you think about it, but we don’t always do it.

Keep wrists neutral

A good way to consider wrist position is to keep the hand in the same plane as the forearm. A slightly more accurate approach is to keep your hands positioned similarly to how they would be while holding the steering wheel of your car at the 10 and 2 o’clock position—slightly in and slightly forward.

Reduce Excessive Force

Excessive force on your joints can create the potential for fatigue and injury. In practical terms, the action item is for you to identify specific instances of excessive force and think of ways to make improvements.

Consider pulling a heavy cart might create excessive force for your back and shoulders. To make improvements make sure the floor is in good repair, that the wheels on the cart are sufficiently large, and that there are good grips on the cart. Another manner of reducing force is to use a hoist for lifting heavy objects, just as a pallet jack.

A final example is having built in or cutout handholds on boxes or carrying totes. Having the handhold reduces the exertion your hands need to carry the same amount of weight.

Vibration

Vibration is another common problem that can benefit from evaluation. As an example, vibrating tools can be dampened to help prevent musculoskeletal disorders.

Keep Everything in Easy Reach

The next principle deals with keeping things within easy reach. In many ways, this principle is redundant with posture, but it helps to evaluate a task from this specific perspective.

Reach Envelope

One concept is to think about the reach envelope, which is the semi-circle that your arms make as you reach out. Occasional use items should be within the reach envelope of your full arm. Constant use items should be within the reach envelope of your forearms.

Frequently, problems with reach are simply matters of rearranging your work area and moving things closer to you. This is not exactly a hard concept to grasp; what is difficult is having the presence of mind to notice and change the location of things that you often reach for. Usually it’s force of habit, and you are unaware that you continually reach for something that could be easily moved closer.

Sometimes, the work surface is just too big, causing you to reach across to get something. One option is just to get a smaller surface. Another option is to make a cutout: this way your reaches are reduced, but you still have plenty of space for things. 

Work at Proper Heights

Working at the right height is also a way to make tasks less taxing.

Do most work at elbow height

Most office work should be done at about elbow height, whether sitting or standing. The most common example is working with a computer keyboard and mouse.

Exceptions to the rule

There are exceptions to this rule, however. Heavier work is often best done lower than elbow height. Precision work or visually intense work is often best done at heights above the elbow.

Sometimes you can adjust heights by extending the legs to a work tables or cutting them down. Or you can either put a work platform on top of the table to raise the work up or stand on a platform to raise you up.

Reduce Excessive Motions

The next principle to think about is the number of motions you make throughout a day, whether with your fingers, your wrists, your arms, or your back.

One of the simplest ways to reduce manual repetitions is to use power tools whenever possible. Another approach is to change layouts of equipment to eliminate repetitive motions. Sometimes there are uneven surfaces that are in the way. By changing these, you can eliminate unnecessary motions.

Minimize Fatigue and Static Load

Static load is holding the same position for a period of time. It creates fatigue and discomfort and can interfere with work.

A good example of static load that most people experience is writer’s cramp. You do not need to hold onto a pencil tightly, just for long periods. Your muscles tire after a time and begin to hurt.

In the workplace, having to hold parts and tools continually is an example of static load. Having to hold your arms overhead for a few minutes is another classic example of static load, this time affecting the shoulder muscles. Sometimes you can change the orientation of the work area to prevent this, or sometimes you can add extenders to the tools.

Having to stand for a long time creates a static load on your legs. Simply having a footrest can permit you to reposition your legs and make it easier to stand.

Minimize Pressure Points

Another thing to be aware of is excessive pressure points, sometimes called contact stress.

A good example of this is squeezing hard onto a tool, like a pair of pliers. Adding a cushioned grip and contouring the handles to fit your hand makes this problem better. Leaning your forearms against the hard edge of a work table creates a pressure point. Rounding out the edge and padding it usually helps.

We’ve all had to sit on chairs that had cushioning, so we understand almost everything we need to know about those type of pressure points. A particularly vulnerable spot is behind your knees, which happens if your chair is too high or when you dangle your legs. Another pressure point that can happen when you sit is between your thigh and the bottom of a table.

A slightly subtler kind of pressure point occurs when you stand on a hard surface, like concrete. Your heels and feet can begin to hurt and your whole legs can begin to tire. The answer is anti-fatigue mats or using special insoles in your shoes.

Provide Clearance

Having enough clearance is a concept that is easy to relate to.

Work areas should be prepared so you have sufficient room for your head, knees, and feet. You obviously don’t want to bump into things all the time, work in contorted postures, or reach because there is no space for your knees or feet.

Being able to see is another version of this principle. Equipment should be ready to use—and tasks should be set up so that nothing blocks your view.

Move, Exercise, and Stretch

To be healthy, the human body needs to be exercised and stretched.

Don’t conclude after reading all the preceding information about reducing repetition, force, and awkward postures, that you’re best off just lying around pushing buttons. Muscles need to be loaded and your heart rate needs periodic elevation.

Depending upon the type of work you do, different exercises and movements on the job can be helpful. If you have a physically demanding job, you may find it helpful to stretch and warm up before and after any strenuous activity. If you have a sedentary job, you may want to take a quick break every so often to do a few stretches or take a short walk.

If you sit for long periods, you need to shift postures:

  • Adjust the seat up and down throughout the day.
  • Move, stretch, and change positions often.

It’s ideal to alternate between sitting and standing throughout the day. For some tasks, such as customer service, an adjustable desk is ideal.

Maintain a Comfortable Environment

This principle refers to both the immediate and overall work environment—the individual work station and the work floor.

Lighting and Glare

One common problem is lighting. In the computerized office, lighting has become a big issue, because the highly polished computer screen reflects every stray bit of light around. But many other types of tasks can be affected by poor lighting, as well. Concerns include glare, working in your own or other shadows, and insufficient ambient light. A simple solution to lighting problems is by using task lighting, such as having a small light right at your workstation you can orient and adjust to fit your needs.