Googlers aren't the only ones to spend time on planes – many people suffer the effects of "Economy Class Syndrome." Here are some tips even for flying veterans – or for that matter, those taking long road, train or bus trips, as similar advice applies. Much of this information can be found at the helpful site AirHealth.

Economy Class syndrome causes blood clots that develop in the legs (deep venous thrombosis, DVT) as a result of prolonged air travel. "Prolonged" can mean a 2-hour flight – and after 2 hours, the risk increases hourly, even if you change flights. If the clot breaks off and goes to the lungs (pulmonary embolus, PE) it can cause death.

Of course, this syndrome can easily occur in business or first class seats too – but it happens more in economy simply because there are more seats and therefore more people sitting.

Sounds obscure, you say? It's not. Some 3 to 5 percent of air travelers develop blood clots, most of which dissolve naturally. The few that don't have significant morbidity and mortality, but most of these can be prevented. However, the more frequently you fly, your chance of developing them goes up: frequent business travelers are about 50 times more likely to develop clots.

Often there are no symptoms until several days after the flight, and the DVT may be mistaken for a cramp. Symptoms may include:
  • Sudden swelling in one leg (a little swelling in both legs is usually normal)
  • Cramp or tenderness in one lower leg
  • Bruise or swelling behind a knee
Chest symptoms (PE) usually appear 2-4 days or more after the initial blood clot, and may include:
  • Shortness of breath, rapid breathing, panting
  • Cramp in your side, painful breathing
  • Chest pain, sometimes shoulder pain
  • Fever
  • Coughing up blood
  • Fainting
If you're thinking this doesn't happen to healthy road warriors, you'd be wrong. Being athletic is a major risk factor, because the slower pulse and resting blood flow rate may lead to increased stasis. Others who need to be on guard for DVT are:
  • Those who've had recent surgery or an injury. Avoid surgery 30 days before and after travel.
  • Personal or family history of DVT
  • Cancer, heart disease, diabetes, and obesity
  • Women who are pregnant, or are taking birth control pills or other hormone therapy
I think I have your attention now - so how do you prevent DVT when traveling?
  • Walk when possible on the plane (or bus or train).
  • Do leg flexing exercises at 30-60 minute intervals. Extend your legs and flex your ankles, pulling up and spreading your toes, then pushing down and curling the toes. Or rotate the ankles by making circles in the air.
  • If there isn't room to extend your legs, start with your feet flat on the floor and push down and curl your toes while lifting your heels. Then, with your heels back on the floor, lift and spread your toes. Repeat this heel-toe cycle five times or more.
  • Exercise your thigh muscles by sitting with your feet flat on the floor and slide your feet forward a few inches, then slide back and repeat. Or extend the legs if possible and isometrically flex thigh muscles.
  • Avoid crossing your legs, or wearing constrictive clothing (knee braces or tight garments, elastic support hose. (Compression hose have been proven effective, however).
  • Stay hydrated - but only with non-alcoholic, non-caffeinated beverages like a Virgin Mary (no vodka), and preferably electrolytic drinks (Gatorade type) – 1 cup every 1-2 hours. Drinking lots of plain water is not recommended (on long flights it can contribute to thicker blood viscosity, which may lead to clots).
  • If you have risk factors (such as history of DVT) talk to your doctor, since these require prescriptions. (Note that contrary to popular belief aspirin does not help prevent these clots because aspirin mainly affects the arterial and not the venous circulation.)
  • Though another standard recommendation is to avoid sleep, I think that would be cruel and unusual punishment given the severe deficiency of entertainment on these long hauls.
Finally, if you think have DVT, do not massage the leg - it can break off the clot and lead to PE. Call your doctor and let him or her know that you have traveled recently, and are having pain or swelling in one leg. The proper test then would be an ultrasound of the leg (not invasive or painful).

Want to read more? There's an extensive list of references of studies at the National Library of Medicine's PubMed service.

Wishing you safe and healthy trips!