Humans are not designed to sit for long periods, but business forces many to do so full-time. A good ergonomic chair helps to mitigate the damage so that desk workers can be productive. There is no universal definition of how to sit for long periods in a healthy manner. However, most ergonomic studies share a consensus. Using key points from different studies, we end up with clear, easy-to-understand guidelines.
Humans are not designed to sit for long periods. We know this because the lumbar spine falls out of alignment when it moves into a sitting position. When standing, a healthy lumbar spine curves inward at an angle between 20-45 degrees. Sitting without lumbar support cuts that angle in half.
As that happens, the pelvis tilts forward until the lumbar curve flattens. Over time, that shortens hips flexors and pulls the whole body out of alignment. The lower back tightens, while core stomach muscles get longer and weaker. At the same time, quad muscles tighten the front of the leg, while hamstrings elongate and weaken from the rear.
Misaligned bodies caused by poor sitting habits are endemic. In America, some studies estimate that 85% of men and 75% of women suffer from anterior pelvic tilt. Misaligned muscle pairs work against each other to twist the pelvis from a neutral position to a tilted one.
The result of such misalignments is a host of health issues that hinder productivity. Those include muscle pain, chronic fatigue, weight gain, and depression.
Core healthy sitting priciples
The fundamental problem is that humans are not designed for sitting long periods. In particular, sitting without support flattens the lumbar curve, throwing the entire body into misalignment.
The most effective method of preventing flattening with adjustable lumbar support. Even so, fixed postures slow circulation and strain muscles. As a result, a range of straight postures works better than a single fixed posture.
Here is the gist of all research in this article, boiled down to three core principles:
Neutral sitting is the healthiest option
For long sitting periods, many studies suggest a (fluid) neutral posture as the healthiest sitting option. A baseline neutral posture involves five steps:
- Plant feet flat on the floor: this supports the weight of the upper body. When feet aren’t planted, the spine must hold up body weight instead.
- Knees above hips: adjust your chair’s seat so that your hips are slightly above your knees. This position places the least amount of stress on the ankles, knees, and hips.
- Tuck hips into the seat: sit as deep into the seat as possible to make proper use of a chair’s back support.
- Use lumbar support: this is a chair’s most crucial point of support. Slight pressure into the lower back reflexively straightens the upper back.
- Straight back: with support from the lumbar and planted feet, sitting straight is easy. Then, keep your head balanced atop the shoulders. At the same time, keep your eyes pointed straight ahead.
The key ergonomic requirements needed to support neutral postures are lumbar support and a reclining backrest. This paper on seated biomechanics explains how lumbar support reduces disc pressure.
This one clarifies that a chair’s lumbar support works best with a recline of around 100 degrees.
Lumbar support is necessary
Lumbar support biomechanics is a complex topic we explain in detail here. To summarize, we refer to Seeking the Optimal Posture of the Seated Lumbar Spine (2009).
This paper compiled top ergonomic studies to establish lumbar support as a necessity for healthy sitting.
Summary of the paper’s findings:
- A healthy standing lumbar curve has an angle of 20-45 degrees. Sitting without lumbar support reduces the curve’s angle by 50%. That reduction increases intradiscal pressure at the third lumbar vertebra by 40%.
- Sustained lordotic support decreases disc pressure, reducing lower back pain.
- Sitting with a back angle of 110° with lumbar support 4 cm deep results in an optimal seated lumbar curve of 47 degrees. That provides slightly more curvature than is needed while standing.
This explains how lumbar support serves as a key ergonomic chair feature. More a more detailed explanation, check out this feature:
Dynamic neutral postures are best
Beyond effective lumbar support, healthy sitting also requires regular position changes. Dynamic (or active) sitting engages muscles around the spine, abdominals, and legs while you sit.
Small recline position changes keep key muscle groups active. As a result, users enjoy a stronger core, improved circulation, and reduced stiffness in the lower back.
Leading ergonomic chair guidelines
It took heavy sifting through dozens of studies to find a healthy sitting consensus. First, sitting for long periods in a fluid (moving) neutral posture places the least amount of stress on the body. Second, using a range of neutral postures keeps the seated body active.
Third, to support dynamic, neutral postures, a chair needs three components:
- Adjustable lumbar support.
- Adjustable armrests.
- Tilt-lock reclining backrest.
Below is a summary of standards from three leading ergonomic science sources. All three lead back to the need for three essential ergonomic components.
BIFMA ergonomic guidelines
The Business and Institutional Furniture Manufacturers Association (BIFMA) was founded in 1973. It serves North American furniture manufacturers by providing furniture safety standards. Manufacturers can then test their products to determine if they meet BIFMA standards.
- Height of seat: should allow the user’s feet to plant onto the floor or a footrest.
- Depth of seat: should be deep enough so that the back of the knees do not touch the front of the seat.
- Seat width: should be wide enough to accommodate the user’s hips.
- Backrest: should conform to the shape of the user’s spine. It should also have lumbar support that maintains the lordotic curvature of the lumbar spine.
- Armrests: should be adjustable up and down, plus in and out. This helps to relieve neck, shoulder, and back stress.
BIFMA also recommends that an ergonomic chair provide a healthy range of motion. The seat and backrest should allow varied postures. The backrest should recline from 90° to at least 115°. The only guideline for seat tilt is to ensure the torso-to-thigh angle is not less than 90°.
Handbook of Human Factors and Ergonomics
The fourth edition of the Handbook of Human Factors and Ergonomics came out in 2012. It is a key reference book for ergonomics researchers, practitioners, and graduate students. Each chapter has a strong theory and scientific base, but with a focus on real-world applications.
Its statement on ergonomic seating:
The purpose of good seating is to provide stable body support and a dynamic posture. It should be comfortable over long periods and physiologically sound. It should also be appropriate to the task being performed.
The handbook defines an ergonomic workstation. It should allow the operator to sit with good posture. They should be able to see the screen without moving their head. The keyboard, mouse, or document they are working on should be easy to reach with minimal effort.
Ideally, the perfect workstation would have a height-adjustable screen, keyboard and chair. Below are key requirements:
Ergonomic chair essential features
The Handbook cites five key features that all ergonomic chairs should have:
- Chair adjustment controls should be easy to operate from a seated position.
- The chair and adjustment mechanisms should be rugged.
- Chairs should have adjustable armrests.
- The seat should be padded to ensure comfort.
- The chair should allow alterations in posture and freedom of movement.
Ergonomic functionality requirements
The handbook also adds brief standards that ergonomic seating should meet:
- Seat Height: should be adjustable by the user so that the feet rest flat on the floor. If the operator is too short to rest feet on the floor, they should use a footrest.
- Seat depth: the seat should be deep enough so the user can sit far enough back to use the backrest without putting pressure on the knees.
- Backrest height: the backrest provides back support in various postures. For full support, the top of the backrest should be at least 18” higher than the compressed seat height.
- Lumbar support: this helps to maintain the natural curvature of the lower spine. The lumbar support area of the backrest should be between 6” to 10” above the compressed seat height.
- Backrest angle: studies have shown that recline angles reduce fatigue. If adjustable, a backrest should recline to at least 115◦.
- Armrest height: armrests at the right height support the neck and shoulders. Armrests should be height adjustable with a range of at least 4″.
Cornell Ergonomic Guidelines
Dr. Alan Hedge is a Professor in the Department of Design and Environmental Analysis at Cornell University. His 2013 paper on ergonomic seating compiled the findings of several leading studies.
Sitting with lumbar lordosis is ideal
A key point in his paper is that healthy sitting requires a pelvic rotation that creates lumbar lordosis. When the angle between the thighs and the body is too small, the lumbar curve flattens or bends outward. That is called lumbar kyphosis. Kyphosis occurs because of the restrained rotation of the hip joint. That forces the pelvis to rotate backward, placing pressure on the spinal discs.
The trick to inducing lumbar lordosis is to use lumbar support. Another method to reverse kyphosis is to use a reclining backrest.
Ergonomic sitting essentials
There are five key findings that lead to ergonomic chair recommendations:
- Proper sitting requires a pelvic rotation that creates lumbar lordosis.
- Lumbar, thoracic, and cervical muscle activity decreases with a backrest incline to 110°.
- Lumbar disc pressure and back muscle activity are lowest with a supported recline angle of 110° – 130°.
- A high proportion of chair users make height adjustments to their lumbar support.
- After 1 hour, there is spinal shrinkage with static sitting. In contrast, the spine expands with dynamic sitting where the seat pan swivels.
Breaks for movement are essential
Beyond Dr. Hedge’s suggestions, ergo.human.cornell.edu adds these recommendations:
Every 20 minutes, stand for eight minutes — while moving for at least two minutes. The absolute time isn’t critical — use these as rough guidelines. The important thing is to take a posture break to stand and move for a few minutes. Only standing is insufficient. You need movement to get blood circulation through the muscles.
To learn more about the importance of movement, ChairsFX spoke with esports physical therapist Dr. Joshua Lee.
His advice for gamers: “The body craves movement. Short rest breaks with exercises are like little snacks. Your body can use these throughout the gaming session to keep you energized.”
Most contemporary ergonomic chair guidelines share the same broad standards. An ergonomic chair should be comfortable, adjustable, and good for your back.
For detailed guidelines, we started with BIFMA ergonomic standards. Then we took standards from the Handbook of Human Factors and Ergonomics. Over those core principles, we layered concepts from Cornell U and Dr. Alan Hedge. All standards are consistent, with no contradicting ideas.
Condensing the gist from all three research sources gives us clear ergonomic chair guidelines. Use these to assess the chairs you’re thinking of buying.
Broadly, your ergonomic chair should support a healthy sitting posture. It should also provide consistent comfort — whether sitting or standing. How you feel when getting up from the chair is as important as how you feel while sitting.
But a chair’s comfort is subjective. It depends on the type of work you do, your physical proportions, and your sitting style. In his defining paper, Dr. Hedge notes that it’s not possible to assess the comfort of a chair by sitting in it briefly. In this writer’s experience, it takes at least a week of full-time use to determine how comfortable a chair is — for your needs.
To ensure the most comfortable outcome, look for these essentials when shopping for an ergonomic chair:
Lumbar and back support
Standing with good posture produces a healthy curve in the five vertebrae of the lumbar spine. Sitting tilts the pelvis forward and flattens the lumbar curve. That causes slouching and health issues.
Sitting with lumbar support of around 4 cm deep prevents that from happening. Maintaining a good lumbar curve prevents the hips from rotating forward. With the hips in place, the upper back has the needed support to stay straight.
In support of a good lumbar support, a chair needs a good backrest. For example, gaming chairs provide excellent back support with adjustable pillows and a tall backrest. The pillows maintain the spine’s natural curves. The tall backrest supports the weight of the upper body while providing plush comfort.
The point of an ergonomic chair is to reduce pressure on your back. With a backrest recline of 110°, lumbar, thoracic, and cervical muscle activity decreases.
With supported recline between 110° and 130°, back muscle activity is the lowest.
A human arm weighs around 6% of total body weight. A 170-pound person’s arms weigh around 10 pounds each. Without armrest support, your spine bears the load of holding your arms up against gravity. When computing, that places unnecessary strain on the spine, shoulders and neck.
In contrast, adjustable armrests discourage slouching while also promoting a neutral sitting posture.
Appropriate chair size
Pricier ergonomic chairs come with a height-adjustable backrest and sliding seat. Those features allow a perfect fit for various sizes. To ensure that lumbar support hits the spot, shorter users can lower the backrest. In a similar fashion, larger users can extend the seat depth for a better fit.
However, many ergonomic chairs do not come with these features. If you can’t adjust backrest height or seat depth, choosing a proper-sized chair is crucial.
Key dimensions to look for:
- Seat width and depth
- Backrest width and height
- Floor to seat range
Larger users should make sure that the seat and backrest width fits their proportions. Smaller users should select a backrest appropriate for their body size. To learn more, check out our detailed sizing guide:
Getting the best value for money
Beyond ergonomic features, it’s also important to ensure good value for money. On one hand, you should try to avoid paying more than you need to. On the other hand, cutting corners can result in a poor chair investment. Keep these aspects in mind when assessing the value of a chair:
- Durability: ergonomic chairs have many complex parts. Many minor things can go wrong, like cracked knobs or broken parts. Cheaper chairs are notorious for making squeaks and weird noises when you move. Many cheap chairs also don’t hold up well under full-time use. Faux leathers can crack, while cheap seat padding can flatten.
- Price: there is a major difference in quality between a $60 office chair and a $900 ergonomic chair. Cheap chairs use lower-grade plastics and metals. They also have less adjustable features than pricier models. Paying more gets you improved ergonomic features and better quality upholstery.
- Warranty: typical office chairs usually come with a 30-day warranty. Cheap gaming chairs come with 1-2 year warranties. Some high-end gaming chair brands offer 5-year warranties. At the top, the priciest Herman Miller chairs come with rock-solid 12-year warranties.
Learn more on this topic in our analysis of gaming chair price range qualities:
Ergonomic seating is red-hot in the work-from-home lockdown era. In the coming months, expect waves of new ergonomic chairs catering to full-time gamers and desk workers. Instead of getting lost in the marketing hype of each new product, put yourself in an informed position to buy the perfect chair. To do that, make sure your prospective new chair meets these basic guidelines:
- Adjustable lumbar support: should extend around 4 cm deep from the backrest. It should also be height-adjustable to fill the curve of the lumbar spine.
- Adjustable armrests: these should be adjustable so that they sync with the height of your desk. Ideally, they should adjust to support elbows and forearms while positioning hands close to the mouse and keyboard.
- Reclining backrest: the scientific consensus is that an ergonomic chair needs a minimum recline range of 90° to 130°.
If the chair meets those basics, then consider other aspects based on your needs. If on a budget, check out cheap gaming chairs under $200. With around $500 to spend, you can get a high-end pro esports gaming chair. At the top of the range are $1500 Herman Miller ergonomic task chairs.
Beyond pricing, there are specialty models for short people, big and tall users, video game fans, and even kids under 4-12 years old. Whichever type of chair you use, the final step is to use it correctly to ensure optimal health benefits. Check out our illustrated, step-by-step Gaming Chair User Guide to learn more: