We spend an average of about seven and a half hours a day sitting down. For most of this time, office-based workers are using an office chair. And that’s sufficient time to make it worth taking a closer look at this piece of furniture. I’m going to explain whether your current chair is just right for you, or what you need to look for next time you buy.
Armrests are a matter of what you’re used to: some people can’t work without them, but others can’t work with them. However from a health perspective they are more than just a good idea, because they take the strain off the shoulders and upper arms and avoid tension in the neck and cervical vertebrae. It’s especially important that armrests are adjustable in both height and depth, because this is the only way to customise them to the individual dimensions of the user. Lateral adjustment of the armrests is also a practical feature, to ensure that the lower arms, hands and fingers remain mobile and the hand muscles and tendons are effectively relieved of strain. The armrests should be at least 20 cm long and 4 cm wide. The optimum position is 20 to 25 cm above the seat.
The backrest is intended to provide the best possible support to the sitter’s back in any position. Individual settings are important here, too. For example it should be possible to adjust the backrest counter-pressure so it follows the body movement of its user and neither offers too much resistance nor tips backwards too freely. The backrest should follow the natural S contour of the spine. The lumbar support is a curvature in the lower area, to lend extra support to the lumbar region.
3. OFFICE CHAIR GUIDE: THE SEAT
The seat is anatomically shaped with the aim of encouraging the sitter to make full use of the seat area, as this is the only way to ensure contact between the back and backrest. To achieve this anatomically-friendly shape, the following conditions must be fulfilled:
A flattened and rounded front seat edge prevents restricted flow of blood to the lower legs
The seat itself should pitch downwards slightly towards the front to encourage circulation in general, prevent a hunched posture and tilt the pelvis into an upright position.
The seat depth adjustment means that the chair can be customised to individual thigh length, which avoids pressure on the backs of the knees from the front edge of the seat and thereby also promotes circulation. Optimised weight distribution across the pelvic bones reduces pressure on the thighs.
Good quality foam for the seat is important so that elastic recovery is retained over the long term and the seat does not wear out – after all, the seat has to support more than 70% of the body weight. So “passive ergonomics”, as it is known, encourages the pressure distribution across the seat to be as even as possible.
As with the armrests, there are also ideal measurements that should be observed. It is important that the height of the seat allows individual adjustment within the range of 42 to 50 cm. A user is sitting in the optimum position on his chair if the angle between the thighs and calves is at least 90 degrees. When the seat height is set correctly for the leg length, the pressure exerted on the pelvic bones is minimal. The return flow of blood and lymph from the legs is then uninhibited.
4. OFFICE CHAIR GUIDE: THE MECHANISM
A device called the synchro mechanism encourages dynamic sitting. It allows the seat and backrest to move synchronously and follow the body, ensuring that the back is constantly touching the backrest. A good-quality synchro mechanism avoids the “shirt-pulling effect” when the sitter moves backwards and forwards on the chair. An individual bodyweight adjustment option means that the same effect can be achieved whether the user is heavy or light, thus guaranteeing comfortable support in any position. The easier it is to use, the better: for example our quick-set adjustment function, which is especially user-friendly. The synchro mechanism also encourages dynamic sitting, which stimulates the metabolic process so that the muscles are always supplied with enough oxygen.
5. OFFICE CHAIR GUIDE: THE NECK SUPPORT
The neck support is a useful accessory for healthy ergonomic sitting. It functions as an extension of the backrest, supporting the cervical vertebra area and relieving strain on the shoulder and neck muscles – especially in a fully-reclined position as you might assume for example when relaxing while talking on the phone. The neck support should definitely be height-adjustable.
6. OFFICE CHAIR GUIDE: UPHOLSTERY AND FABRIC COVER
Upholstery and fabric are attractive to look at, but they can also incorporate thermoregulatory and ergonomic functions. Their quality is especially noticeable on hot summer’s days: if clothing sticks to the skin, they are not ideal. To achieve maximum sitting comfort, the upholstery and fabric should allow exchange of moisture and body heat. The seat is designed to support this principle, with its open-pore foam properties, as well as not using any adhesives at all for the upholstery and covering fabric. If it is straightforward to change the fabric or even the whole upholstery, an office chair will remain a loyal companion to its owner for many years. Our tip: offers heating and ventilation functions, similar to a car seat. The ventilation in particular makes it impossible for clothes to stick to the skin.
As well as its thermo regulatory functions, upholstery can often fulfil ergonomically beneficial roles, for example our patented system, which is concealed within the seat and backrest. This air-filled foam cell reacts individually to body weight and movement: if it senses pressure, air is gently rerouted to support the body position. That prevents a posture that is bad for the spine, and supports dynamic sitting.
