DVT in athletes - What to look for and how to prevent.

While I am well and truly on the mend with the clot I feel that some education on prevention and early detection for the athletic community may prevent other athletes from suffering the same condition I have.

Firstly why are endurance athletes at higher risk of deep vein thrombus (DVT)?

Blood composition, the nature of heavy training and racing, and destination racing are all significant risk factors. The body adapts to endurance training by producing more red blood cell so oxygen can be more readily supplied to working muscles. This is essential for training adaptation but it means that the blood has a higher viscosity (ie. thicker).

Endurance athletes also tend to have slower resting heart rates then non-athletes, giving this thicker blood more time to pool and therefore potentially clot. An extreme case of this clotting occurring is in professional cyclists died in the late 90’s and early 2000’s who had extremely low resting heart rates and a very high haematocrit (high red blood cell percentage of the blood, which equals thicker blood) and as a result several cyclists developed clots in their vascular system. This is an extreme case as most of, if not all the cyclists, were taking performance enhancing drugs which inevitably contributed to this condition occurring.

Heavy training and racing can lead to periods of dehydration, further increasing the red blood cell to plasma ratio of the blood. Furthermore trauma of either the red blood cells from shear forces (pounding the pavement) and/or damage to the endothelial lining of the veins (like in my case) can lead to clot formation. Destination racing adds travel into the equation. Longer travel times equates to longer periods of immobilisation and the potential for the blood to pool within your limbs.

So, in summary endurance athletes are at high risk of clot formation.

What are the signs of a DVT and what can you do to prevent a DVT from occurring?

Identifying a DVT.

In general, the more obvious signs and symptoms of a DVT, particularly in the lower limb, is swelling, point tenderness, redness and feeling of tightness in the affected limb. Not all of these will be present with certain DVTs, as in the case of my upper limb DVT. In some instances more subtle symptoms may be experienced and it takes some reasoning to suspect that a DVT may be present. If there is noticeable swelling and a feeling of fullness/tightness is experienced within a limb, a DVT should be suspected. The investigation of choice for a DVT is an ultrasound and these can be performed at any hospital or radiologist.

Prevention is the key!

As mentioned above, increased blood viscosity is a potential risk factor for developing a clot. Ensuring adequate hydration both during and post training and racing is crucial. In most cases it is also important to supplement the body with added electrolytes and sugar in your water bottle to maintain the correct balance within the blood. A popular way to measure whether your body is adequately hydrated, is as simple as measuring your body weight pre and post exercise and from that determining the amount of fluid you have lost.

It is well documented that blood pooling can occur when the body remains still for long periods of time such as with long flights. The best and very simple way to prevent this is get moving. If on a long car trip, have frequent rest stops and walk for a short period to get the blood flowing. If on a long haul flight, make the effort to stand and walk around the cabin as often as possible. Another now popular way to prevent pooling is by applying compression garments to the limbs.

The final prevention note is perhaps the least recognised. As in my case, the repetitive damage to the vein wall under my collarbone caused the gradual formation of the clot. In this particular situation, there is usually an underlying technique and biomechanical issue contributing to the injury. I now know that my right shoulder biomechanics were potentially impacting on my swimming technique and this combined with the higher swim volume I was completing, possibly led to the DVT developing. The bottom line is – address any technique issues with all sports and don’t forget to add any appropriate body maintenance exercises into your program.

That’s it for now. I hope this little article has provided some insight into the detection and prevention of DVTs in the athletes.

Check back soon for the latest update. Happy training.


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