You know how your feet swell by the end of a long flight?  That’s your body not being able to get blood back out of your feet as fast as your heart can pump it into them.  People who fly are at a 3-4x higher risk for blood clots.  This risk increases to 6x more if you have a window seat.  (See text box at the end of the post copied from the CDC website for additional risk factors for blood clots.)

 If the blood sits there and stagnates, there is a possibility it could clot.  If it clots, this blood clot could travel to your lungs or brain and cause serious problems, including death.

 Quick lesson on blood flow: (since for most of us if its been a few weeks since we learned about our cardiovascular systems in school!)

The heart pumps blood out to the organs, muscles etc. via the arteries.  Arteries have muscular walls that help the oxygen rich blood get to your whole body.  After the blood has delivered its oxygen load to the tissues, the blood returns to the heart via veins.  Unlike your arteries, your veins do NOT have muscles in their walls.  In order to keep blood moving, vein depend on the pressure created by your heart and arteries, as well as the activity of your skeletal muscles.

 What this means when it comes to socks, sitting and travel:   The blood gets pumped into your feet.  Normally when you are up walking around, your calf muscles act as a pump around your veins to keep the blood traveling back toward your heart.  When we sit, the vein in the back of your knee called the “Popliteal vein” gets squished, creating a prime spot for your body to decide to build a clot.  True graded compression socks are tighter at the ankle and looser at the calf.  They should follow specific, steady decreases in pressure—tighter at the ankle, looser at the calf. Our bodies like to ‘follow the path of least resistance”, and this graded type of compression directs the blood to keep flowing toward the heart.

Check your socks.  Some socks and sleeves for athletics provide consistent compression across the calf.  While this may help for sports, it is not ideal for travel—it can actually CAUSE problems if you have an underlying circulation problem.  This can also be true of very high compression socks (even if they are graded compression!).  Unless you have a medical recommendation to do so, you should stay at 20 mmHg pressure or below for travel.  

PODsox, when properly sized, provide 18 mmHg at the ankle and 14mmHg at the calf.  (AND they’re fun!  Who would of thought to make functional fun?…ummm…we did….  🙂 

What can I do?

-Know your risk factors (check out the list from the CDC below.)  If you have more than 1 of these risk factors, consult your doctor before you fly.

-MOVE—wiggle your feet, stand up, walk around, go to the bathroom etc

-True graded compression stockings such as PODsox can give your body the boost it needs to keep blood moving during long flights and periods of inactivity. 


So now you know!  Pull your PODsox on and go see the world!*

(*If you have any history or possibility of problems with circulation, consult your doctor before wearing PODsox or any other compression garment.)


About the Author:  Stephanie is a Doctor of Physical Therapy as well as a board certified women’s health specialist.  In addition to co-founding PODsox, she also follows her passion by working in a busy outpatient PT clinic.  


Venous thromboembolism (VTE) risk factors (From CDC website)
General risk factors for VTE include the following:
• Older age (increasing risk after age 40)
• Obesity (BMI >30 kg/m2)
• Estrogen use (hormonal contraceptives or hormone replacement therapy)
• Pregnancy and the postpartum period
• Thrombophilia (such as factor V Leiden mutation or antiphospholipid syndrome) or a family history of VTE
• Previous VTE
• Active cancer
• Serious medical illness (such as congestive heart failure or inflammatory bowel disease)
• Recent surgery, hospitalization, or trauma
• Limited mobility
• Central venous catheterization