Seated Posture Tips

The way we sit is a factor of the chair itself as well as the other equipment in the work station. Here are six tips to lead toward correct seated posture.

#1: Support your feet

If your feet are hanging or tucked under you, the increased pressure on the backs of legs can impair return circulation from the feet. This can lead to or aggravate swollen ankles and varicose veins.

• Support feet on the floor, or on a foot rest if your feet don't reach the floor
• Use an angled foot rest for high heels
• Don't put your feet on the spokes of the chair
• Adjust chair height for comfortable keyboarding (more points on this in the future)

#2: Ankles forward of the knee

It is very tempting to put your feet on the casters of the chair. Some people do it for variety, others because their feet don't touch the floor. When the ankles are behind the knee, our balance in the chair is affected. Tucking the feet under pivots the upper body forward. Conversely, if you are reaching down or forward to the keyboard, or looking down at documents or the monitor, you will tend to lean forward. This encourages you to put your feet on the spokes of the chair. Keeping the ankles forward of the knee assists return circulation from the feet and encourages you to lean back in the chair.

• Don't put your feet on the spokes of the chair
• Support feet on the floor, or on a foot rest if your feet don't reach the floor
• Adjust chair height for comfortable keyboarding (more points on this in the future)

#3: Three finger gap behind the knee

Behind the knee is a surprisingly sensitive area. As the fleshy area of the thigh tapers, you can feel the tendons on the outsides and a soft area toward the center. Through the soft area is the passage for some blood vessels and nerves. Even though you may not have known that, when you sit down you instinctively protect the area behind the knee. If the seat pan of the chair is too long and might put pressure on that area, most people will automatically sit forward on the chair. This could lead to the back and pelvis curling down (slouching) to get some back support or to you sitting upright and unsupported. Both postures will lead to back discomfort in a very short time.

When selecting a chair then, it is important to find one that has either the right size seat pan or a sliding seat pan. The goal is to have about a 3 finger gap between the front of the chair and the back of the knee when your are sitting comfortably against the backrest.

• Support feet with the ankles forward of the knees
• Three finger gap behind the knee
• Front of seat pan should not press into back of leg
• Adjust depth of seat pan
• Add a pillow or foam to build up backrest and fill in the gap

#4: Knees at or below hip level

One of the goals of correct seated posture is to have the midpoint of the knee lower than the midpoint of the hip. For most people this can be accomplished adjusting the seat of the chair so that it is parallel to the ground. Because most of the population has some "personal cushion" to sit on, this will make the thighs slope down slightly. A dramatic slope is not necessary, nor recommended. If the seat of the chair slopes too much, the user will feel like he or she is sliding out of the chair and will brace his/her feet. This is even worse if the user is wearing smooth or slippery materials such as lined pants or pantyhose.

A common misconception is that the knees should be higher than the hips. This is based on a poor interpretation of some research in the 1950's. In that research, they found that there was higher pressure in the lumbar disks when a person was sitting upright and unsupported. When the entire chair (seat and back) was tilted back and the upper back was supported, the lumbar disk pressure was lowest. With the entire chair tilted back, the knees appeared to be above the hips - but the angle between the thighs and the torso was still about 90 degrees. The morale of this story is that the knees should be at or below hip level while the back is supported.

Adjust chair height Adjust chair angle Support feet Remember.... support feet ankles forward of knee 3 finger gap behind knee

#5: Lumbar spine supported

The way we sit is a factor of the chair itself as well as the other equipment in the work station. In this, the fifth of six tips to lead toward correct seated posture we will explore how your foot position affects the upper body (and vise versa). Each month I will give another tip until each aspect of the computer work station is adjusted to meet your individual needs.

The first thing I look for in a chair is good lumbar support. When I run my hand down the backrest, there should be a good solid roll protruding to help the lower back maintain it's natural curve. In a standing position, the lower back naturally curves inward. When we sit, we lose the natural curve. The goal of good seating is to help restore the natural curve.

In office, one of the most common seating problems that I encounter is that the lumbar support is too low. Either the backrest has never been set correctly or it had gradually fallen down. The lumbar support should fit snuggly into your lumbar spine - at about the waistband. When the lumbar support is too low, it puts pressure on the sacroiliac joints (near the dimples), pushing the pelvis forward. This makes it harder to use the upper part of the backrest.

adjust backrest height adjust backrest angle increase the depth of the lumbar support Remember.... support feet ankles forward of knee 3 finger gap behind knee thighs parallel to the ground or slightly angled down

#6: Upper Back Supported

Sit up straight!....that's what your mother told you, right? Well, sorry folks, she was wrong. True she didn't want you to slouch, but sitting up straight, with the upper back unsupported actually causes back pain. We should lean back so that the middle of the shoulders are slightly behind the middle of the hip. This makes the hip angle one or two degrees more than 90.

When the upper back is not supported, the postural muscles must be continuously active to keep the body from falling forward. This is because the spine is at the back of the body and the front has all the heavy stuff - organs, chest, shoulders, abdomen, arms, head, hands..... The tight postural muscles to maintain an upright position restrict their own blood supply creating a build up of lactic acid and carbon dioxide and don't let in enough oxygen and nutrients. This is what creates the burning feeling in muscles. Letting the chair support the weight of the upper body allows the postural muscles to relax, ensuring adequate blood flow.

adjust backrest angle lean back pull in to desk / keyboard make sure arm rests don't interfere Remember.... support feet ankles forward of knee 3 finger gap behind knee thighs parallel to the ground or slightly angled down lumbar spine supported

More Posture Tips Focusing on the Arms and Hands...