The Office Chair
By Kirsty Angerer, The Travelling Ergonomist on 23rd Apr 2019
A swivel, spinning, or revolving chair has a single central leg that allows the seat to rotate 360 degrees clockwise or anticlockwise. The first swivel chair, otherwise known as an office chair, was invented by Thomas Jefferson. Office chairs were developed around the mid-19th century as more workers spent their shifts sitting at a desk, leading to the adoption of several features not found on other chairs. The office chair was strategically designed to increase the productivity of clerical employees by making it possible for them to remain sitting at their desks for long periods of time. A swivelling chair with castors allowed employees to remain sitting and yet reach a number of locations within their work area, eliminating the time and energy expended in standing.
In the 1970s ergonomics became an important design consideration and since has been the pinnacle of not all, but many office chairs. For those that may not know the definition of ergonomics, the International Ergonomics Association define it as:
“Ergonomics is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimise human well-being and overall system performance.”
To be ‘ergonomic’, a chair needs to fit to the user’s needs and some adjustments that should be considered are seat height, seat depth, backrest height, angle and armrest height. Ideally you also want a chair that enables you to sit dynamically so that in a seated position you are able to incrementally move whilst being fully supported.
To help us decide on the specifications for a chair, we often use a branch of ergonomics called anthropometrics. This concerns body measurements, ranges of joint movement, reach distances and clearance dimensions. All of these components are very important in making informed decisions about a chair. Not only chairs but also desks, computers, keyboards, mice and any other tools you may find on your desk. We must remember that the chair is a component of the wider system of a workstation and isn’t the only thing we should consider when thinking about office ergonomics. After all, office ergonomics is all about the health, wellbeing and productivity of people and this incorporates everything we interact with in an office environment.
Let’s take our focus though to chairs and perhaps more interestingly sitting. Over the last couple of years, the conversation around sitting has exploded, particularly due to many news articles suggesting that ‘sitting is the new smoking’. In some instances, these articles make a valid point as there are health issues related to long periods of sitting but we must make the distinction that it is not sitting that is bad, it is sitting for long periods in poor postures that is bad.
When you sit for too long your gluteal muscles, otherwise known as bum muscles, can become weakened. These large muscles help to stabilise us when walking for example so if they are weakened, you are at more risk of injury. Sitting can also cause your hip flexor muscles to shorten which can lead to problems with your hip joints. Of course, if you are sitting for too long, you are not burning as many calories, your digestion is not as efficient, so you retain fats and sugars as fat in the body. There are also studies that suggest our cardiovascular system doesn’t work as well, we have poor blood circulation and very often poor posture.
Trunk flexion or the leaning forward posture is one of the leading causes of lower back pain around the world. Statistically, 80% of adults will experience some kind of back pain at least once in their lives. Around 5.6 million working days in the UK are lost each year due to back pain. This is costing the UK economy £10.7bn per year.
It might sound all doom and gloom but there is good news. Luckily for you many furniture manufacturers are designing ergonomic chairs to encourage a more neutral posture and more movement even in a seated position. Perfect. Now we need to figure out what chairs are best for us and whilst no mean feat, there are specific things we can look for in a chair to make more informed decisions.
There are many types of chairs out there from ‘bad back’ and orthopaedic chairs, ergonomic chairs, executive style chairs, stool chairs or saddle chairs, and alternative chairs such as kneeling chairs and stability balls.
There are also many styles of office chairs such as mesh back, foam seat, mesh back and mesh seat, fully foam based, ones with neck rests, ones with lumbar support and ones without, ones that are fixed and those that move, chairs with minimal manual features and chairs with an overwhelming array of manual features.
The first thing we need to establish is why you need a new office chair. Are you looking to merely update your current office chair, are you suffering with a particular injury or discomfort, are you pregnant and need more support in your chair, are you looking to fit out an office with a good ergonomic chair for your employees, are you short or tall and having trouble getting a chair that suits your stature, or you just don’t know what features to look for in an office chair such as should it have armrests or not?
Whatever the reason, we’ve got you covered and in this blog series, each will tackle a specific challenge.
Before you start to make decisions about office chairs though, we need to understand how the body works, how the body moves, how the body interacts with things.
Ultimately, we want our office chair to enhance our performance without affecting our health and wellbeing.
Now don’t get me wrong we don’t need to learn how the body works at a cellular level, but we do need to understand the basics.
Our body is made up of many systems, and we are going to focus on the musculoskeletal system, and more specifically the spine.
The spine consists of 33 bones (24 vertebrae, the sacrum and the coccyx which are made up of fused vertebrae). There is a spinal disc in between each vertebra. The vertebral column is subdivided into different structures.
You have the Cervical region, the thoracic region, the lumbar region and the sacral region.
Have you ever heard the saying ‘sit up straight’? Your mum and dad have probably told you to do it since a very young age at the dinner table, then you get to the office and people tell you to sit up straight when you’re working.
Well technically we can’t because our spine is not straight. There are actually 4 curves. The thoracic and sacral curves are called primary curves. The cervical and lumbar curves are known as secondary curves.
There are 7 vertebrae in the cervical region. The first 2 cervical vertebrae have unique characteristics that allow for specialized movements. The Atlas (C1) holds up the head. The atlas forms a pivot joint with the axis (C2). This permits rotation at the neck (like when you are shaking your head to indicate no). There are 12 thoracic vertebrae which consists of the upper back.
There are 5 lumbar vertebrae which make the lower back. These are the biggest and least mobile as they support most of the body weight. As you increase the weight on the vertebrae, the intervertebral discs become increasingly important as shock absorbers. Lastly you have the sacrum and the coccyx which are fused vertebrae at the bottom of our spine.
When we look for an office chair, we must consider how the chair is designed and find one that encourages a neutral spine as much as possible. When you stand, your spine is in an ‘S’ shape curve which we call a neutral spine and when you sit (particularly in a slouched posture) you often will sit with a ‘C’ shape curve. We want to try and encourage this ‘S’ shape curve as much as possible so a chair with good lumbar support is really important. When our lower back is supported properly, the rest of our spine should also be supported.
Our next blog will be focused on choosing a chair for those that are shorter or taller than the average. What’s ‘average’ anyway? We’ll be focusing on what features you should look for, what other tools you may need to encourage a more neutral posture and how your desk height may also be affecting the way you sit.
Kirsty Angerer, The Travelling Ergonomist
Kirsty Angerer is a Certified Professional Ergonomist, Frequent Flyer, Workplace Wellness Advocate, Fitwel Ambassador, and Self-Confessed Ergonomics Nerd. She has worked in the areas of ergonomic program development and training for managers and employees for quite some time, now with a global client base. Travelling the world regularly, she strives to make it a more healthy and comfortable place.