Following our article about Blood Clots and Rowers, We had some great comments from readers and this email from a medical Doctor. 

Gil Solomon, MD wrote

Searching for studies with the term athletes and DVT, there are several confirmatory points in your Blood Clots and Rowers article and several that are not.

The athletes who presented did not have classic signs of a DVT with leg swelling – they usually just had an ache, which they ascribed to a strain.  Athletes are better able to withstand pain and also a decrease in lung capacity, so the diagnosis is often missed.  Also, MDs do not expect athletes to have a DVT, so that is also in agreement. It is also known that a previous DVT damages the vein, predisposing to another DVT.

I found an interesting article about chronic exercise reducing risk factors for clotting, as contrasted with acute exercise in untrained individuals that increases the clotting factors and the risk:  “By and large, regular (or habitual) physical activities of moderate intensity reduces thrombogenesis, presumably by enhancing fibrinolytic capacity and possibly, by reducing the blood coagulation tendency. Conversely, both coagulation and fibrinolytic cascades are stimulated by acute strenuous exercise.”  Acute versus habitual exercise, thrombogenesis and exercise intensity.
Lee , Kaeng: Thrombosis and haemostasis [0340-6245] yr:2004 vol:91 iss:3 pg:416 -419 

So it is possible that someone who rows regularly would have a lower incidence.  We don’t know because there are no separate statistics.

I don’t think lactic acid has an impact.  Dehydration does seem to cause an increase in clotting factors, but there would not be a way to confirm this is a risk factor in athletes through study, so it is just theory, and one could propose an alternate as follows: Although your 55 year old rower is acutely dehydrated in the Florida heat, I would suppose he, and all of us, replenish our fluid loss beginning right after we are done.  At least that is standard advice.  And during the period of time immediately after rowing, one’s heart rate is still elevated and still pumping the blood around, so the alternate theory is that during that window of time with the relative dehydration, there is also increased blood circulation that would prevent stasis and clots.  Again, maybe the reality is that the incidence of DVT is actually lower in athletes because of this.

 
 
So the summary of my comments would be:

1. 1/1000 rowers per year might be expected to develop a DVT if the risk is the same as the population so it is a possibility
2. Symptoms can be missed but if there is pain in any extremity (one can have a DVT in the arm) and swelling, rowers should ask to be checked for a DVT.  
3. If there is any decrease in exercise tolerance or shortness of breath, that needs evaluation.  It could be a pulmonary embolus or it could be a cardiac or lung issue, such as a bicuspid aortic valve, like many of those on the cardiac athlete website, who were equally unaware of their narrowed valve.

The incidence of DVT is 1/1000 for all comers including those with cancer and other risk factors so doesn’t apply to athletes.

With the exception of upper extremity thrombosis with athletes that primarily use their arms such as baseball players and tennis players, I didn’t find anything that would increase the risk in rowers. Actually for the reasons I stated above, incidence is probably lower. However the points about missing the dx remain.

Also, there are risk factors for competition followed by flying, where the competition can increase clotting factors and then being sedentary on a plane can be a risk. So there should be good hydration and periodic movement for any long plane flights right after a competition.

Mike Creamer writes

This is very interesting to me because I too am a Masters rower in my 50s who had a similar experience with blood clots in recent years. The first one happened about four years ago and a second exactly one year later. Both clots were in the arteries in my lower leg which I was told was very unusual as they usually occur in veins. My doctors were never able to tell me why this happened as I was also told I was very heart healthy with no blood abnormalities or predisposition to clotting.

It never occurred to me that it might have anything to do with my intense rowing workouts! In hindsight I was doing some hard erg training in the New York humidity at the time I got both clots. Both clots were removed successfully and I was also put on a course of Warfarin but now I just take a daily aspirin. I resumed my erg training within a week or two of both surgeries and I continue to train intensely without any further issues. Thanks for the links. I look forward to learning more about the possible connection between lactate, dehydration and blood clots.

BTW, one possible theory given by my cardiologist as to why my clots were in arteries is that he discovered I had a miniscule hole (PFO) in my heart. With this a clot can travel from the venous system into the arterial system. So they closed the hole!

And Peter Jago says:

An interesting article. Thank you for sharing it. There is useful information on the web on practical ways to help reduce blood lactate during exercise. One that I found is at:
https://www.wikihow.com/Reduce-Lactic-Acid-Build-up-in-Muscles.

Understanding the signs and causes of lactate build up seems to be the starting point to finding a solution. Then managing and developing workouts with this in mind, keeping hydrated, adding bicarbobate (baking soda) to drinks, and making changes to your diet are all tools to prevent DVTs and keep training.

This case highlights one problem that Masters athletes face. We all have to learn about and manage our ailments ourselves to some extent and cannot rely entirely on the health professionals. There is useful information and help groups out there. As the population ages and the number of people carrying on with or taking up sport increases, there is a need for more information, research and advice for Masters athletes who want to carry on training and working out. The management of arthritis related conditions is another topic.

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