Deadly blood clots from sitting: Are you at risk?

01 March 2019

Are our desk jobs killing us?

We’ve all had those days where deadlines are pressing, your boss is calling, and a work day turns into 8 hours (or more) of prolonged sitting behind our computers.

While we are sitting at our desks, rushing to complete tasks, we might not have the extra time to spare to consider our cardiovascular health in these situations.

More specifically, we might not know that we are at risk of developing a potentially life-threatening blood clot in our legs when we sit for an excessive amount of time.

What exactly are blood clots?

A blood clot is a gel-like clump of blood that forms in a vessel and is commonly referred to as “thrombus.” They most commonly develop in the lower legs.

Sometimes a blood clot can dislodge and travel from the site it was formed. When a blood clot travels, it is called an “embolus.”

blood clot

Blood clots form in three main ways – when there is an injury to the blood vessel wall, when we are sedentary for too long, or when certain factors make the blood thicker, or more viscous, like inherited clotting disorders.

Blood clots are concerning for our health because they can travel from the veins in the legs and lodge themselves in the blood vessels in the lung, which can in turn damage part of the lung tissue.

Alternatively, if the clot is large, it can become lodged in the heart, halt blood flow, and cause sudden death.

Blood clots that become trapped in the lung or heart are common, with almost a million cases a year in the US alone. Nearly a quarter of instances cause sudden death and up to a third will ultimately be fatal.

Who is at risk for developing blood clots?

While there are a variety of factors that can put one at risk for developing blood clots, such as inherited clotting disorders, certain types of cancer, obesity, birth control or hormone replacement therapy, prolonged immobility is a well-recognized risk factor for developing blood clots.

When we are sedentary for an extended period, “the blood becomes sluggish, pools, and more prone to form a clot,” says Antonis Gasparis, MD of the Stony Brook Vascular Surgery Division.

Alternatively, when we are actively moving our legs, the muscles in our calves help to keep our blood flowing by acting as “mini-pumps” that assist in pushing the blood back on its journey towards the heart. Doing frequent leg exercises helps to “increase the calf pressure, which helps expel venous blood out of the leg,” he continues.

Until recently, those thought to be at highest risk of immobility-related blood clots included those with prolonged bed rest, paralysis, and those who endured long flights or car rides.

But what about prolonged periods of sitting at work? Are we at risk for blood clots developing then?

With the rise of technology coupled with long work hours, researchers hypothesized that prolonged work- and computer-related seated immobility could also increase the risk of blood clots.

To test their theory, researchers Healy B, Levin E, Perrin K, et al studied the risk of blood clots for those working long hours at desk jobs, which was defined as “being seated at work and on the computer at home, at least 10 hours in a 24-hour period and at least 2 hours at a time without getting up.”

Their research study identified that prolonged work- and computer-related seated immobility was associated with a 2.8-fold increased risk of developing blood clots.

Additionally, for each hour longer spent seated in a day, the risk of developing a blood clot increased by about 10%.

This study suggested that there needs to be a greater awareness of the role of prolonged work- and computer-related seated immobility in the cause of blood clots as well the development of occupational strategies that will help decrease this newly identified phenomenon.

Another study published in the Annals of Translational Medicine Journal has coined a new phrase for this type of occurrence, known as “e-thrombosis,” meaning blood clots that have specifically formed when a person is behind a computer screen for extended periods of time.

How can you prevent blood clots at work?

Sitting for prolonged periods can hamper blood flow. When blood becomes stagnant, it is at a higher risk for clotting. However, when you are forced to work behind a screen for hours on end, what can you do?

Get up and move!

Remember how those calf muscles act as mini-pumps to push the blood back towards the heart? To help counter the health risks of desk jobs, frequent breaks from your desk and short walks will help get your blood moving and lower the risk of forming blood clots.

Or better yet, invest in an adjustable sit-and-stand desk which not only has ergonomic benefits, but encourages active movement without hindering your workflow. With the electronic height adjustable desk offered by FlexiSpot, it has memory pre-set, so you only need to press the memory button to adjust your working posture quickly. As you are working, throw in some occasional calf raises to really get that blood pumping.

Commit to staying active

As mentioned, obesity increases your risk of developing blood clots. Committing to an active lifestyle with regular exercise keeps your cardiovascular system healthy while also lowering the risk of blood clots.

If you work in a profession where it is inevitable to work long hours, consider investing in office equipment that allows for exercising while working, such as desk bikes.

There is a wide array of desk bike solutions that allow you to stay in motion throughout the day while performing desk-bound tasks, including simple pedal exercisers, under desk bikes, or fully integrated sit-stand desk and exercise bike combos. These allow you to exercise throughout the day and keep your blood moving, all the while completing the tasks at hand.

While the research relating to prolonged sitting at work and its association with an increased risk in developing blood clots is still in its early stages, establishing a movement-based lifestyle will help reduce the chances of cardiovascular concerns and instill a healthy lifestyle within the ever-evolving demands of the workplace.

Regardless of how you choose to approach your long workday, George J. Todd, MD of Mount Sinai urges, “The bottom line: It is very important when flying or sitting at a desk working, to get up and walk around at least every 60 to 90 minutes.”


  1. https://myheart.net/articles/pulmonary-embolism-the-killer-clot-in-the-lungs/
  2. https://renaissance.stonybrookmedicine.edu/surgery/blog/new-dvt-guidelines-dispute-economy-class-syndrome-prolonged-sitting-is-real-cause
  3. https://medlineplus.gov/ency/imagepages/18120.htm
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2966881/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174183/