In my last post, I shared some tips on features to look for in task seating. The fundamental features discussed were seat height, seat depth, and tilt tension. Today I would like to concentrate on some of the advanced features (also known as bells and whistles) available in office seating.
For long-term, task intensive use, advanced features enhance the ability to custom-fit the chair to each user’s physical requirements and personal preferences. Advanced adjustments and features distinguish high performance chairs from general office seating. There are five features to consider for users who sit for long periods each day – lumber support, adjustable armrests, seat pan angle, backrest height and angle, and a headrest. Providing these adjustments will reduce back and shoulder pain and help workers stay focused on their job.
Good lumbar support can be the single most important element in defining chair comfort. The lumbar support should fall somewhere between 6 and 10” from the seat pan. Of course, different people prefer different locations for lumbar support. When able adjust the lumbar support, some prefer their support high, and others like it low. Additionally, some backrests tend to pull the lumbar support up or away from the person when reclining, so proper support is not maintained. Look for a chair design that holds the lumbar support in the same relative position when fully reclined and upright.
A recent study by Fred Gerr and colleagues found that 58% of computer workers reported neck and shoulder symptoms during a one-year period. In a related study, computer workers who used chairs equipped with armrests reported significantly less neck and shoulder pain and disorders. One probable cause of shoulder pain is muscle fatigue triggered by lack of support for the arms while keyboarding and using the mouse.
Height, width and pivot adjustments improve the ability to properly adjust the arm cap so that computer users can work with their arms close to their torso and get support for the elbows and forearms. These adjustments also ensure that a computer user can support his or her arm even if they have to reach for the mouse.
In a nutshell, the benefits of adjustable armrests are:
Armrests relieve loads pm the neck, shoulders and arms.
When the forearms or computer operators are supported, there is a lower incidence of neck and shoulder discomfort.
Supporting the arms while keyboarding significantly reduces muscle activity in the upper back.
Positioning armrests under the forearms enhances keying posture and allows free movement of the hands and wrists.
Armrests may help computer users type more lightly.
Seated posture improves when large forearm/wrist supports are used by computer operators.
If non-adjustable armrests are provided , make sure that users can get close enough to the worksurface to perform their tasks. Consider discontinuing armrest use if:
The user’s arms are put into an awkward position.
Shoulders are noticeably hunched.
User leans heavily to one side.
Seat Pan Angle
Adjusting the seat pan angle is another way for task intensive computer workers to change posture. Research shows that the best weight distribution occurs on a rearward sloping seat. Angling the seat pan forward and getting the hips higher than the knees is also beneficial because it opens the trunk angle. Seats that automatically change angle as the user moves promote posture change even further.
Extensive user observation has shown that computer workers often do not angle their seat forward, mainly because in many chairs the user slides forward on the seat. Seat pan shape or seat angle adjustment can be designed to allow the knees to drop lower than the hips without the user sliding forward. When selecting a chair, consider looking for this more advanced design, which allows a beneficial posture change.
Backrest Height and Angle
People who prefer to lean back in their chair while working should have a backrest that reaches the shoulder blades (at least 20” high). High backrests provide upper back support and also help stabilize the neck and head in the fully reclined position. High backrests have been found to relieve static muscle loads on the abdomen and back during prolonged office work. Maintaining a slightly reclined position helps keep the lower back in a recommended posture. Also, the backrest will carry more upper body weight, helping to reduce muscle load and pressure. Leaning back in the chair is an excellent way for users to rest back muscles while working. Good chair designs limit the amount of head and hand travel as the user reclines, maintaining proper distance from the computer display and keyboard.
The last feature I want to talk about is often offered as an option on high performance seating. A well-designed headrest provides additional support for the upper body while in an upright or reclined posture. It can also help position the head while viewing the computer display. Look for a padded headrest adjustable for both height and depth that supports the neck or base of the head.
The advanced chair features that have been discussed can make a significant difference to a chair user who spends long hours in their task chair. By properly adjusting a chair to your body, a chair user can stay comfortable and reduce the risk of back, shoulder and neck pain.