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Understanding Office Chair Ergonomics

Ergonomics is one of those words you may hear thrown around here and there as you research office chairs, looking for the best fit for your body. Essentially, that is what ergonomics means – finding the best fit for your body. Ergonomics is about more than just office chairs, of course. It also includes fitting job tasks, desks, computers, and keyboards to the individual user. Why go to so much trouble to make tasks, furniture, and electronics fit individual people? The answer is: to reduce the risk of harm. Sitting improperly, placing strain on certain body parts, repetitive tasks – these are all ways people can injure themselves in the workplace and at home. An injury is not only a sudden incident, such as dropping a hammer on your foot. An injury can also be caused slowly over the course of time from using office equipment that does not fit your body correctly.

The human body is not meant to sit for extended periods of time. For centuries, humans spent large portions of their days moving about to hunt, gather resources, build things, farm, and so on. It has only been in recent years (the past century or so) that we have begun spending entire days sitting in chairs. Since as a species we have spent most of our time on our feet, our bodies are adapted to finding the most comfort in this position. In order to find comfort in a seated position, we cannot change our bodies so we must change our environments. A very important part of that environment is the thing upon which we are sitting – an office chair.

When it comes to office chairs, there are a few very important ergonomic concerns: arm rests, back rests, seat height, seat width, and seat depth. I have taken the time to research this topic thoroughly and have found that there are a few basic suggestions that doctors, agencies, and companies all agree on when it comes to those four factors. I have made it my goal to bring that information to you in a one short, neatly packaged article.

The Importance of Spine Alignment

I am not a doctor or a chiropractor and I will not pretend that I know nearly as much as one of these professionals would. What I do know is that it is important to maintain a properly-aligned spine. Many people think that this means having a perfectly straight back, but that is not the case. In fact, your back has a natural S-shape from top to bottom, moving outward at your shoulders and inward near the bottom of your back. It is important to keep your back aligned in that S-shape. Your back should be straight from side to side, not leaning to one side or the other. Moving your spine out of its proper alignment for too long a period of time places extra stress and strain on important joints, muscles, and nerves.

The spine is very important. It houses your spinal cord, which more or less contains your nervous system. Your nervous system is what connects your organs and brain and keeps your body functioning. Maintaining a healthy back helps you maintain healthy joints, muscles, nerves, and countless other internal systems. Of course, if you want more information on this topic, you should speak to a doctor or a chiropractor who can give you more detailed information. For the purposes of this article, it is primarily important to know that a healthy back promotes a healthy body. Therefore, it is very necessary to find the right office chair to keep your back healthy.

Arm Rests

There has been a lot of debate about arm rests on office chairs. Some experts claim that they can be helpful in keeping the arm at a 90-degree angle, whereas others are concerned that arm rests promote leaning. Leaning is seen as a bad thing, because it pulls the spine out of alignment and places extra pressure on certain neck and shoulder muscles.

Among those experts which believe arm rests are okay to have on office chairs, there are a few of pieces of advice upon which they all agree. First, your arm rest should not interfere with your work. A common problem with many arm rests on office chairs is that they protrude so far forward that they prevent the user from pulling the chair far enough under the desk. If your arm rests stop you from pulling your chair under the desk and you find yourself having to lean forward to work, you have a problem.

In terms of fitting your chair to your body, you want to make sure that your arm rest barely touches the underside of your forearm and does not extend forward to your wrists. Barely touching the underside of your forearm means that your arm rest is encouraging you to keep your arms bent at a 90-degree angle. If they were up much higher, they would be scrunching your shoulders up toward your ears, cramping your trap muscles, and putting undue strain on your neck. The purpose of an arm rest is not for you to lean on it – the purpose is to give your elbows support if they cannot sit flat atop your office desk while you work. This is also why you do not want the arm rests to extend forward toward your wrists.

Back Rests

Lumbar support is one of the most important aspects of back support when it comes to office chairs. You may have heard the term ‘lumbar support’ before, or this concept may be completely new to you. Basically, your back has natural curves. The average human spine has an S-shape – curving inward at the lower spine and outward near the shoulders. The lumbar spine is the lower part of your spine. Any good office chair will support the inward curve at the bottom of your spine with its own curve that fits right into that space. The chair should have an S-shape that mimics the shape of your spine to promote proper alignment. This reduces pressure on nerves and discs (the soft areas between your vertebrae/spinal bones).

There are no one-size-fits-all options when it comes to lumbar support. Since every spine is slightly different, the part where you need support will be different. Depending on the length of your torso/back, the location of your lumbar spine may be different than the location of the lumbar support on your chair. You may get lucky, after sitting on tens or hundreds of chairs, and find one that fits you perfectly. A much simpler option, however, would be to choose a chair with adjustable built-in lumbar support and a back rest adjustable in height. You will want to be able to adjust the back upwards or downwards to properly align its lumbar support with the natural curve of your own back. The best (and usually most expensive) office chairs will also have adjustable support on either side of the lumbar spine. This support helps to hold your spine in an upright position and decreases the likelihood that you’ll slouch to one side or another as you sit.

Some chairs will allow you to adjust the angle of the back rest as well. This can be very helpful if you find yourself performing different tasks in your office chair. You may need to sit upright for typing or writing, but will want to allow your back to relax by reclining slightly when you are reading or talking.

Seat Height

Seat height is also important to good back health. A chair which sits too low will place pressure on certain parts of the back as well as adjacent muscles and joints. A chair which sits too high will place strain on the back as your legs dangle and pull on your nerves. In a perfect world, you will find yourself with a desk that is just the right height for you. If you are lucky enough to find yourself in this situation, experts recommend that you adjust your seat according to your knee height. Simply stand in front of your chair and adjust it so that the top of the seat or seat cushion reaches the top of your kneecap. This may be a two-person job, so consider eliciting the help of a family member, friend, or co-worker. The purpose here is to ensure that your legs are bent at a 90-degree angle and that your feet touch firmly to the floor while resting your arms on the surface on your desk, also at a 90-degree angle.

If your desk is too tall for you to adjust it as described above while maintaining your arms at 90-degree angles, you will need to try a different method. If this is the case, it is suggested that you adjust your chair according to your desk. Position the height of the chair so that your arms are at 90-degree angles on the surface of your desk. Your feet will not sit flat on the ground with your legs at 90-degree angles. You will have to purchase a small foot stool to make up for this difference and maintain good back health.

If your desk is too short you will need to seriously consider purchasing a desk that can accommodate you properly. No amount of chair adjustments will make up for a desk which is too short.

People who fall within a height range of 5’1” to 5’11” will find that chairs adjustable from 16 inches to 21 inches in seat height will work just fine for them. People who are five feet tall or less will need to find a chair that is adjustable to less than 16 inches. People who are six feet or taller will likely need a chair which adjustable from 21 inches to 43 inches.

Seat Width

Many people will find that an average seat width is able to accommodate them just fine, but this is not always the case. There are two major concerns when it comes to seat width. First, some seats are made with contoured foam, designed to reduce pressure on certain parts of the rear and lower spine. People who find that they are too narrow or too wide to sit comfortable inside these contours will not be able to reap their benefit. In fact, sitting improperly atop those contours may actually increase pressure on important areas and cause more discomfort.

Another consideration is that, if you have arm rests, you want them to sit at a comfortable distance from your body. You do not want arm rests which squeeze you into your seat and press against your sides while you are trying to work. Similarly, you will not want arm rests that are so far away from your body that you find yourself reaching outward to rest your elbows on them.

Many chairs come with arm rests which adjust not only up and down, but also side to side. This allows you to pull them in closer to your body or push them out farther away, depending on your frame size. That being said, adjusting arm rests can only account for so much when it comes to the ergonomics of seat width. Primarily you want to be sure that the seat comfortably fits your rear end. If you cannot sit on the seat without your hips protruding over the edges, it is too narrow for you. Similarly, if you sit on the seat with so much room to spare that you find yourself sitting on strange lumps and bumps instead of sliding into the contours of the seat, you have chosen a chair which is too large for your frame.

Seat Depth

Seat depth is also an important factor in selecting the right office chair for you. You will want to make sure that the chair is not too deep or too shallow. If the chair is too deep, you may find yourself sitting on its edge and not making proper use of your back rest, or sitting so far back that your legs cannot comfortably bend at 90-degree angles. Some chairs have adjustable seat depths. You can adjust the depth by pulling a lever which allows you to slide the seat forward or backward. Extremely adjustable chairs also allow you to lift the back rest high enough to slide the seat underneath it, making the depth even smaller. In the end, you want to be able to sit with your feet touching the floor and your back touching the back rest with about 2 inches of space between the front of the seat and the bends of your legs.

The Importance of Adjustability

In the end, no two chairs are made the same just as no two people are made the same. Unfortunately, we do not live in a world where it is feasible to create one chair for every person. You will likely find yourself having to settle for one of the many different types of chairs that are available on the market today. In doing so, it is very important for you to find a chair which is highly adjustable so that you can customize it to fit your body as well as possible.

The Conclusions

Here is a quick overview of what we have discussed in this article. If you select a chair with arm rests be sure that they do not interfere with your being able to pull your chair under your desk. Adjust your arm rests so that you elbows or forearms barely touch their surfaces when your arms are at a 90-degree angle.

Your back rest should provide adequate lumbar support and should be adjustable in height so that you can match the lumbar support to the curve of your spine. Back rests which have adjustable angles can also be good, but are not a necessity.

Your seat height should be adjusted to fit your desk, not your body. If your desk is too short, think about getting a new desk. If it is too tall, adjust your seat so that your arms are at 90-degree angles. If your feet cannot touch the floor, purchase a small foot stool.

Your seat should be wide enough that you do not feel squished, but not so wide that you cannot fit into the contours of the cushion/wood/plastic seat. Arm rests which adjust inwards and outwards can be helpful for this problem, but only to a certain degree. The depth of your seat should be adjusted so that you can sit with your back against the back rest and have approximately two inches of space between the front of the seat and the bends of your legs.