Prolonged immobility has long been known to increase the risk of blood clots forming in veins in the legs (the medical term for which is deep venous thrombosis).  Blood clots in the legs can be quite painful and debilitating but they can also travel to the lungs which can be life threatening.  So doctors use medicines or inflatable leg squeezing devices to prevent blood clots in hospitalized patients who are bed-bound.  But there is a much more common time when we all are fairly immobilized – travel.  On long trips we frequently sit still for hours at a time, a perfect setting for blood in our leg veins to pool and clot.

An article in the current issue of Annals of Internal Medicine formally reviewed the existing studies on travel-associated deep venous thrombosis and concluded that travel increases the risk of a blood clot almost threefold, and that each 2 hour increase in the duration of travel increases the risk by 18%.

The likelihood of a blood clot in any single episode of travel wasn’t estimated, but is presumably very low, given the huge number of people who travel.  So this should not make you cancel your trip to see Aunt Martha.  Instead, follow these common sense suggestions from the Centers for Disease Control anytime you have to sit for longer than four hours:

• Get up and walk around every 2 to 3 hours.
• Exercise your legs while you’re sitting by:
  • Raising and lowering your heels while keeping your toes on the floor
  • Raising and lowering your toes while keeping your heels on the floor
  • Tightening and releasing your leg muscles
• Wear loose-fitting clothes.

Tangential miscellany:

That reminds me.  If you happen to fly on US Airways this month, pick up their in-flight magazine.  They printed my post on cyberchondria.

Learn more:

Centers for Disease Control and Prevention Tips for Healthy Living:  Deep Vein Thrombosis

Annals of Internal Medicine article:  Travel and Risk for Venous Thromboembolism