We have conducted an interview with Haruyuki Asada, a Certified Professional Ergonomist (CPE), as well as Executive Researcher from Okamura Corporation, to share some tips on how to choose a suitable ergonomic chair and what features help us maintain a healthy sitting posture.
1. Seat Height
Seat height is a basic feature of a task chair. A good position for the seat height is to have the knees at an angle close to a right angle. At this point, the heel should be grounded enough to prevent it from raising from the floor when you move your feet back and forth.
If the heel raises from the floor when your knee is in the correct position, there are countermeasures such as using a footrest to raise the heel position.
2. Headrest
A headrest can support the position of the neck and is highly effective when the user is reclining and leaning backward a lot. Okamura designed headrests that allow adjustments such as movable up and down, forward and backward, etc.
3. Lumbar Support
Most of the Okamura’s chairs come with lumbar support option, a part that supports the lower back. The lumbar support is said to be preferred by people with back pain, and is a little firm, making it feel as if your lower back is being pushed gently from behind. Basically, it fills the gap between the backrest and the curve of your waist, and you adjust the top of the lumbar support so that it fits optimally into the curve of your back.
4. Reclining
The optimal posture for the angle of the backrest (reclining) varies depending on the type of work, but the basic rule is to try to prevent your back from moving away from the backrest by leaning forward, and it is preferable to make sure your head is in line with your spine so that the weight is held properly.
When working with a computer, it is also important to avoid a downward-facing posture. The display should be at eye level, and if you are using a notebook PC, you can use a stand to elevate the display to reduce the burden on the body.
5. Seat Depth
The basic premise of how to sit in a chair is to sit deep in the seat. Sit deep in the seat, making sure your back is against the backrest, leaving no space in between. If your hips shift forward on their own, there is a high possibility that the chair is not best suited to your body and posture.
Most of Okamura’s office chairs have seat depth adjustable functions. The office chair can be adjusted back and forth, make a small gap between the front of the seat cushion and back of your knees so that about two fingers can fit. The tip of the seat should not hit the back of the knee or put pressure on the back of the thigh where large blood vessels run.
6. Armrest
An armrest supports your elbows and reduces the burden on your shoulders, especially if you use a computer keyboard. The keyboard should be placed in front of you so that you can operate it with your elbows resting on the armrest. At this time, adjust the height of the armrest so that your shoulders do not lift unnaturally. If you don't have an armrest, you can put your elbow on the desk.