Deep vein thrombosis (or DVT) is when a blood clot forms in a vein deep in your body, usually in the legs. Symptoms can range from nothing to swelling, pain, cramping, soreness, discoloration or even a feeling of warmth in your leg(s).
But the real trouble starts if one of these clots breaks free and moves to your lungs, says Anthony Carcella, a mountain biker and physician assistant in emergency medicine.
“Having DVT in your leg is usually not a big deal,” Carcella says. “But if it gets to your lungs it can block blood flow, which is really dangerous and possibly fatal.”
So what are the risk factors, and what can you do to diminish them?
1. You’ve inherited some risk
Carcella says some people simply inherit a disorder that makes their blood clot more easily (Factor V Leiden, for instance). But this condition all by itself is not a guarantee of problems. It does, however, increase the likelihood of issues when combined with other risk factors, such as age.
Blood clots can happen at any time in life but are more common after the age of 40; that risk jumps even higher after 60. Add obesity to this equation, and you up the ante even further.
So while you can’t turn back time or change your genetics, you can watch your weight.
2. You sit too much
Whether it’s because they’re sitting for multiple hours on a transatlantic flight or confined to a hospital bed post-surgery, even healthy, active people experience increased DVT risk when they don’t move around for prolonged periods of time.
This is because your calf muscles contract when you walk around, which helps keep blood flowing.
If you’re on a long-haul flight, Carcella recommends getting up and moving around every 30 to 60 minutes.
And even when sitting, you can flex your foot back and forth, which helps contract your calf.
Compression socks can also be helpful because they apply gentle pressure to the calf, ankle and foot, lessening swelling and promoting proper circulation.
3. Your hormones are in flux
It’s a double whammy for women here. When pregnant, the increased pressure on your pelvis and legs also affects your veins, ramping up the chance of DVT. This is especially true if you also have a family history of clotting issues.
Oral contraceptive birth control and hormone replacement therapy have also been linked to DVT, as the oestrogen in these medications can raise your blood’s ability to clot.
4. You’re obese – or a smoker
Having a BMI (or body mass index) over 30 increases your chances for DVT. This measure indicates how much body fat you have compared to your height and weight.
Fortunately, this isn’t an issue for many if not most cyclists, who keep the weight down by cranking out kays on their bike. Most don’t smoke either, which is another DVT risk factor.
Smoking makes your blood stickier than normal and also harms the blood vessel lining, increasing the chance for clot formation.
5. You’ve had cancer, heart problems or surgery
Having surgery, cancer, heart failure or even an irregular heartbeat can all contribute to a greater risk of deep vein thrombosis.
Surgery, especially when below the waist, ups the ante both because it often leaves you temporarily immobile, and also because of the inherent damage done to blood vessels during the procedure.
Cancer patients, meanwhile, have seen a greater DVT occurrence, which has been linked to chemotherapy treatment.
In cases of heart failure, your body’s ability to pump blood is reduced, which increases the chance and impact of DVT.
And people with an irregular heartbeat are more susceptible to blood not being thoroughly pumped through your heart’s ventricles.