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Athletes and Blood Clots: Know Your Risks

BY John Post, MD

Athletes are at particular risk of developing a potentially harmful blood clot, or deep vein thrombosis (DVT). Here's why, and how you can manage the risk.

John, the head lifeguard at our local pool, is finally back in action. He’d been on vacation in New Orleans a few months ago when he noticed that his left foot was swollen. “It was funny. I hadn’t twisted it or anything” he told us. Upon seeking medical help, John was found to have a blood clot in this leg, also known as deep vein thrombosis or DVT. Recovery was a long road—but could have saved his life.

What is DVT?

DVT is diagnosed 750,000 to 1,000,000 times per year in the United States alone— Serena Williams and Hilary Clinton are both survivors. The condition, while common, is also quite serious. Symptomatic clots can lead to low oxygen levels in the blood, heart failure or even death—and a small percentage of these clots actually break loose, move up the venous system and lodge in the person’s lung. In this location they’re called pulmonary embolus, or PE, and they can be rapidly fatal.

What are the Symptoms of DVT?

Although some athletes have no symptoms with DVT, many others will experience swelling and/or pain in one leg more persistent than standard sore muscle pain. The symptomatic athlete may also demonstrate sudden shortness of breath, chest pain or discomfort, increased pain with deep breathing or cough. They might be dizzy or light-headed, have a rapid pulse or even cough up blood.

What are the Risk Factors in Developing DVT?

Unfortunately athletes are a “perfect storm for a DVT,” says Dr. Jim Muntz of the Ironman Sports Medicine Center in The Woodlands, TX. Physical fitness often correlates with a low blood pressure, which can be exacerbated by dehydration around racing or training. This sets athletes up for a “slowing or sludging of the blood, possibly leading to a leg clot” according to Muntz.

Athletes on birth control pills or post-menopausal estrogen; those with a positive family history; or those who spend long periods sitting or laying down post-race are also at particular risk. It also doesn’t help if the athlete has pre-existing bruising or inflammation.

Think about your last race: maybe it was hot, and maybe you were a little behind on fluids. Perhaps you had a long drive or a flight coming up and you’re healing from a crash a few weeks prior. Most of the time you’ll be fine (and even if you do get a clot, most dissolve on their own) but it’s also good to be aware that these are all risk factors in creating a potentially serious condition.

When to Seek Medical Attention

If you notice any of these symptoms, and notice that the risk factors apply to your situation, it’s worthwhile to seek a prompt medical evaluation. It can be days, even weeks after a clot forms before symptoms surface, and they can be deceptively subtle. Simply put, if you have pain or inflammation that’s not going away, ask your doctor. We want you at the race start line again next year!

6 Ways to Minimize Your Risk of DVT

  1.  Simply being aware that DVT/PE is a possibility in the endurance population is a start.
  2. Ensure that you restore normal hydration immediately following your race.
  3. If your race plans include travel, increase your fluids and electrolytes significantly.
  4. Simple leg exercises like those seen in the in-flight magazines (including leg pumps, ankle circles, and hip/knee flexes) will help, as well as getting out of your seat in the plane or car and walking around at regular intervals. Most of us goal-oriented triathletes just want to get to the destination, right? But 2 minutes at the rest stop moving, walking around, using those leg muscles can make all the difference.
  5. If your trip is greater than six hours, Runner’s World sports doctor Bill Roberts recommends wearing knee-high compression socks and taking an Aspirin—though you should always talk with your physician before using it to reduce the risk of blood clots
  6. Know your history. Athletes with a positive family history, or ones who’ve suffered previous blood clots should ask their doctor about the pre-flight use of one of the newer oral anticoagulants short term.

Below are a couple resources if you’d like to read a little further on blood clots and athletes:


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About John Post, MD

Dr. Post has a long history with triathlon including 6 Kona finishes and an Orthopedic Surgery practice in Virginia caring for, among others, injured triathletes. He now enjoys giving back to the sport by being a World Championship Transitions volunteer every October. If you find yourself on the pier in Kona, please stop and say hi to “the man in the red hat.”