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Why do my legs turn blue whenever I sit for a short time?

When I sit in class for more than 15 minutes or sometimes even less, my legs turn a blue color. This also happens when I'm standing without walking much, such as waiting in a line. Basically, whenever I'm not moving around for a while. Is this blueness caused by varicose veins? What can I do to keep my legs from turning blue during my 50 minute classes?


Doctors Answers (3)

The venous blood which fills the veins in our legs must pass against the force of gravity and against the pressure in the abdomen to get back to the heart. The calf muscles normally pump this blood out of our legs when we walk or pump the ankles up and down. When we sit or stand still, the venous blood collects under a great deal of pressure in the veins of the legs. Over time, this stretches the tiny veins in the skin which fill with the dark venous blood and turn the skin a blue or purple color when we sit or stand. Walk frequently, avoid prolonged sitting or standing when you can do so, wear elastic support hose, and maintain a normal body weight.

Blood circulates out under pressure, but tends to pool in the legs due to gravity. The majority of your blood volume (about 70 percent) is always on the slow-moving, low pressure venous side of the circulation. Activity, exercise or use of your leg muscles provide the muscular force to lift this blood up out of the legs and back to the heart. There are one-way valves located in the larger veins that act to keep venous flow directed toward the heart. Prolonged standing or sitting causes more blood to accumulate in the legs, producing a blue color, distending veins to be more visible, and can produce aching and soreness. Walking or other activities will improve this rapidly. If walking is not possible - such as when you are in a class, or traveling in a car or airplane - then consider moving (rocking) your foot up and down while resting on the heel or front of the foot. This minimal movement is adequate to effectively lift blood out of the legs and reduce venous pressure and congestion.

This is not caused by varicose veins. This does not fit into any pattern I am aware of so perhaps start with an evaluation with your internist.

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