Stand Up on Long Flights for Good Health

Doctors and medical researchers warn that prolonged sitting during long airline flights may be hazardous to your health.

Medical studies now show that sitting for extended periods in cramped quarters puts you at risk for developing a pulmonary embolus. This potentially fatal condition occurs when a blood clot forms somewhere in your body - such as your legs - breaks loose and then blocks an artery leading to one of your lungs.

This problem, which can develop even if you have no history of heart or lung disease, also can result during other forms of travel. But it is more common on long airline flights.

Doctors, therefore, have coined the term economy-class syndrome for this condition. Fortunately, there are several practical steps you can take to prevent it.

Where do the clots form? Most pulmonary emboli originate as blood clots in the deep veins of the legs or pelvis. These clots often form in conjunction with a condition called thrombophlebitis, inflammation within the veins.

Some clots break off and travel through your veins and through the right side of your heart, eventually to lodge in one of your pulmonary arteries. A single, large embolus that blocks a pulmonary artery can cause instant death.

Fortunately, most clots are small. They can cause difficulty breathing or sharp chest pain when you take a deep breath. If diagnosed early, pulmonary emboli may respond to treatment with various medications. Only rarely is surgery needed to remove a clot.

You are at greater risk of developing a clot if you have sluggish blood flow or ''stasis'' in your veins - especially when you sit still for many hours.

Some people are at higher risk of developing blood clots. They include pregnant women, women who use birth control pills, people with varicose veins or a history of thrombosis and persons with blood conditions.

You may not be aware that a blood clot has formed during your flight. In fact, a clot may not dislodge until several days or weeks later when you make a quick movement. Because of this time lapse, you may not recognize the airline flight as the time during which the clot formed.

Despite its name, economy-class syndrome does not respect economics. Blood clots can develop whether you sit in first class or in the coach section. Our advice to prevent this from occurring during airline travel:

Wear loose, comfortable clothing. This includes the selection of shoes.

Extend your lower legs occasionally.

From time to time, tighten and loosen the muscles of your abdomen and buttocks.

Take a few slow, deep breaths periodically.

Walk the aisle at least once an hour.

Ask your doctor if it is appropriate for you to use aspirin when you travel. Small doses of aspirin may help prevent clots from occurring. But remember, aspirin is a potent drug.

If you have had problems with thrombosis in the past, wear elastic support hose (available for both men and women) when prolonged sitting is unavoidable.