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Lower
Extremities Topics |
The Lower Extremities, defined here, are your buttocks, legs and feet. Complaints by VDT users about the lower extremities are far less than that of the back or neck, but they are not uncommon.
When sitting, you put pressure on your buttocks, legs and feet.
A significant portion of your body weight falls on a small area of the buttocks. Fortunately, the tissue in your buttocks are designed to support your weight. The tissue in your thighs, however, is not designed to be load bearing.
 Buttocks and Leg Muscles |
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The largest nerve of your body, the sciatic nerve, travels from the spine, through the pelvis and behind the thigh bone. Branches from this nerve travel all the way down to your feet. Compression of these nerves can cause your legs and feet to "fall asleep".
Causes of Lower Extremity Discomfort
During prolonged sitting, your legs and feet can swell. This is due to a progressive accumulation of blood in the capillaries of your legs and feet. One researcher has found that, in a workday, the legs increase their volume (swell) by 4 percent.
This pooling of blood in your legs is primarily due to the sedentary activity of sitting.
By sitting in a poorly designed seat or with poor posture, such as with your legs crossed or sitting on top of a leg bent underneath your buttocks, you place stress on the nerves and blood vessels in your legs. This can cause compression of the nerves which leads to numbness or pain. This can also constrict blood flow to your feet which can result in a sensation of coldness.
Preventing Lower Extremity Discomfort
Avoiding prolonged static postures while sitting and using a properly designed and adjusted chair, are two key elements in preventing problems of the lower extremities. When working at your VDT, it is important to periodically change your position and move your legs. You can stand up and move or perform exercises while at your workstation. This will increase the circulation of blood to your legs and feet resulting in less swelling and discomfort.
You should also make sure that your chair is adjusted properly. You need to adjust the height so that your thighs are parallel to the floor and your feet lie flat. If you cannot achieve this position, you may need a footrest. If you are very tall you may find that you need a higher chair.
The backrest depth of your chair should be adjusted forward in order for your knees to slightly extend beyond the seat pan. The edge of the seat pan should also be rounded, allowing you to sit comfortably. This will take pressure off your legs, at the back of the knee.
Your chair should also be cushioned to provide both firm support and comfort. A chair that is too soft will not provide you with adequate support. On the other hand, a chair that is hard will cause discomfort.
Once your chair is adjusted properly, you should avoid sitting incorrectly in the seat. Do not cross your legs or sit with a leg tucked underneath you.