DVT for cycling

12 weeks ago i was sitting on a train travelling home from London after a hectic day at work. I was in a huge amount of discomfort. I had badly cut my knee the previous weekend and couldn’t really bend my leg, but something was much more seriously wrong than that. My left calf was so swollen up I had to take my boot off, and putting my foot on the floor was agonising, feeling like my leg was severely cramping up. I had been struggling to walk all day. There was simply no position I could stand, sit or lie in that felt comfortable.

After a quick Google search, the symptoms pointed to one thing only, something that I had thought would never happen to me as a highly trained elite cyclist with a healthy diet and lifestyle, and apparently no genetic predisposition to it, despite my family history. It was highly likely that somehow, mysteriously, I had developed a blood clot in my leg – a Deep Vein Thrombosis (DVT).

This blog is not about my personal suffering – I have written about that elsewhere. Instead, in trying to understand why this had happened to me, apparently against all the odds, and the path to getting back on my bike and fulfilling my racing ambitions, I undertook a lot of research. I want to share this research so that others can understand why DVTs in elite cyclists are more common than you might imagine, and how others who suffer the same fate can recover and get back to training safely and quickly.

When diagnosed, DVTs are generally defined as ‘provoked’ or ‘unprovoked’. Provoked DVTs have one or more obvious triggers, many of which I will describe in more detail below. If none of these triggers are evident, it is instead defined as ‘unprovoked’. Whilst the initial treatment is the same for both (painful Heparin injections subcutaneously for a few days, followed by a 3 month course of oral anticoagulants to stop the blood from clotting at all), provoked DVT cases are dismissed with no further investigation.

Interestingly, many of the common triggers are as likely in elite sportspeople (especially cyclists) as they are in the general population. Let me run through them and explain.

  1. Trauma – plenty of cyclists can experience sufficient trauma to suffer from DVTs through crashes. Deep wounds and heavy bruising can both be triggers. Whilst my wound was not superficial, it was still deemed not bad enough for stitches. Nor was there significant bruising.
  2. Immobilisation – linked to trauma, if a limb (upper or lower) is immobilised for a period of time with bandage or cast, clots can form as the blood is not circulating adequately. So crashes that lead to broken bones or soft tissue injuries could be a trigger.
  3. Physical damage to the blood vessel (endothelial) lining – this is where the interior wall of the vein becomes damaged, prohibiting blood flow. It was suggested to me that because we sit on one position on our saddles, putting a lot of pressure on the groin, it could be possible to cause sufficient damage to the vein wall to trigger a clot. Maybe more tenuous (this one is completely my own theory, not based on anyone else’s research), as a cyclocross racer, I do lots of jumping back onto my bike, and several times over the season got it wrong, causing bruising to the location where my clot eventually formed.
  4. Severe dehydration – keeping hydrated helps the blood to flow. The more dehydrated you are, the more likely your blood is to clot. It is unlikely that a 2-3 hour race in the usual British climate would cause sufficient dehydration on its own, but longer races in hotter conditions, or racing after a period of illness (especially diarrhoea or vomiting) without rehydrating is a known trigger.
  5. Altitude Training – we all know the merits of altitude training in improving oxygen uptake by the blood. But staying too high too long, or going too high too fast, is a known trigger for clotting.
  6. Long journeys – everyone knows about the association of DVTs and long haul flights. But you don’t have to be in a plane at 20,000 feet. Sitting in a cramped space in a car, bus of train for an extended period of time can have the same effect. How often do racing cyclists bundle themselves back into their cars after races, dehydrated, and drive for several hours without moving or stretching their legs. A prime opportunity for clotting.
  7. One for the girls – the combined contraceptive pill. Another trigger that most people know about. And young women who want complete control over their bodies so they can maximise training and racing will go on the pill for reasons other than contraception (e.g. To control frequency, heaviness and pain of periods). And although the combined pill is not recommended for women over the age of 35, the more mature ladies racing often pass under the radar as they (or should I say ‘we’) don’t look that old and are left on the pill too long.


There are obviously things we can all do to reduce the risk factors. Beyond this, as I mentioned, some of us can be genetically predisposed to DVTs. There are several genetic mutations, the best known being Factor V Leiden. These are some of the first things that are tested for with an unprovoked DVT. If you have family history of clotting, you may be able to persuade your GP to refer you for testing before any symptoms. I was tested 20 years ago, with negative results, hence my assumption about not being genetically predisposed.

Aside from wanting to get an answer to the question ‘why me?’, it was also absolutely essential for me to understand the prognosis for getting back on the bike and back to racing. To be honest, there is a sparse smattering of information out there. I couldn’t even get a definitive answer on ‘what happens to the clot’, let alone ‘when can I start walking / running / cycling?’  Just as with other more standard injuries like fractures, NHS doctors treat everyone the same, and don’t really think about why a highly trained elite athlete might need something different. With a DVT, the immediate risk of exercising is dislodging the clot and sending it on a beeline towards the heart, causing the much worse Pulmonary Embolism (which can be fatal). Intensity (I.e. Heart rate) needs to be kept ridiculously low. Some advice I read said 2 weeks of gentle walks only, but the trusted source I found, an NHS consultant with a specific interest in Thrombosis and cycling, said 4 weeks. So, 4 weeks it was! I can’t say my walks were gentle, but I got away with it. I then did 2 weeks at my Level 1 intensity (not even fat-burning), and at 6 weeks was given the freedom to push up to my aerobic limit. At 8 weeks I was assured that I could train unrestricted. I started racing (time trials only) in Week 11.

Time after clot Training Intensity
0-4 weeks Gentle walking only
5-6 weeks Level 1 cycling
7-8 weeks Fat-burning / endurance (Level 2) cycling
9+ weeks Full intensity

A secondary, but equally important consideration is the secondary risk associated with the blood thinning medication. Other cyclists I spoke to who have suffered DVTs commented that they had opted not to risk any training where the risk of drawing blood was elevated, and therefore opted to train only on the turbo for the entire course of treatment.  Although this was a risk for me too, another equally big risk was my mental health.

So many cyclists I know use cycling as a way to manage stress, anxiety or depression. To suddenly have that sense of freedom and relief taken away for 4 weeks, let alone 3 months is immensely difficult. I was hugely relieved when my consultant suggested that riding on the road was fine as long as I was careful and always wore a helmet. Road racing was clearly not an option, but I wouldn’t have enjoyed them anyway having lost a lot of fitness in the 4 weeks of doing nothing. Much more important was spending the time to re-build fitness, strength and confidence. I didn’t have to race at all while on medication, but with recovery going very well, I decided with my coach it was worth doing a couple in preparation for some post-medication target races.

I have experienced some other side effects of the medication. It feels like months since I had a really good nights sleep. Not being able to get to sleep and waking early have become the norm. Training has made me much more tired than I have come to expect over the years, so I have found myself having to focus much more on recovering. Getting dizzy and light-headed on a frequent basis is something else I have had to deal with, and this was noticeable and slightly scary in the two time trials I did.

So, in summary, I have learnt not to take my health for granted. DVT is only one of many conditions that can come along to knock us down. We can all mitigate the risk by exercising, eating healthily and staying hydrated. But you can never predict what life will throw at you. I want to raise awareness of this condition so that others can recognise the risk factors and symptoms, and catch the condition before it gets more serious.

There are vague plans for a fundraising event for Thrombosis UK, watch this space!


Karen PooleAbout the Author: Hi, I’m Karen (Poole) and I’m super-excited that Cycling Torque have invited me to be one of their guest bloggers! As a friend recently said in his blog, I am a ‘self-proclaimed gob-shite’ from Yorkshire. I’ve classed cycling as my first sport since 2011 (after ‘retiring’ from international orienteering when I decided I was too old!), although I have very early memories of me riding a bike around the leafy lanes of the Cartmel peninsula in Cumbria, so have probably always had cycling in my blood.

I might be a competitive cyclist, but nothing beats the sheer joy of a long hilly ride in the beautiful landscape that is Great Britain, exploring new roads and meeting new people with a common interest. I hope you enjoy reading my ‘Ramblings on Two Wheels’. If you want to know more you can follow me on @karenpoole44 (Twitter), @Hambletonhobbit (Instagram) or find me on Facebook.