At the beginning of July I was finally diagnosed with Iliac Arterial Endofibrosis (IAE) [edit: actually it’s more appropriate to call what I have Iliac artery flow limitation]. This is a chronic condition where the main artery delivering blood to one leg becomes constricted or kinked near the hip, limiting blood supply to the lower working muscles… which are kind of important in cycling.

There are some fantastic articles explaining the condition in detail and its relevance in cycling, so I won’t repeat much of what’s already written. I want to focus more on my own experience with the condition and how it’s changed my perception of training and racing. But for more details about the condition and possible risk factors, check the links below.

Velonews Feature: Arterial disease and cycling
Cycling Weekly – Iliac artery furring: Is surgery the cure?
Veraldi et al, 2015. Arterial endofibrosis in professional cyclists.

For me the major symptom is severe burning pain in my Left lateral quad during high intensity efforts. My Left leg also loses significant power at higher intensities. Once symptoms begin they won’t resolve until I can fully rest for 5-10 minutes to allow blood flow to normalize. So once I start to feel it during a race, there’s no coming back.

I remember this breakaway in 2017 was horribly painful, but my average power was barely Sweet Spot. Could never figure it out at the time.

My whole racing career (which only goes back to 2014) I’ve been confounded by a significant L/R power imbalance. I’ve investigated, analysed, experimented, and tried everything possible to address the imbalance and find a cause, but I’ve never made any real progress. I’ve always been stuck at around 45/55% at higher intensities.

I always figured my L leg fatigued quicker than my R due to some biomechanical or musculoskeletal issue. I thought my L leg was somehow less well-trained than my R, and that I just needed to train better to bring it up to target.

I can’t recall when I started to feel the burning pain that really told me I had a problem, but the pain was certainly notable last season in 2017. I think as my fitness improved, the vascular deficiency became more of the limiting factor.


Gastown Grand Prix 2017 – Utter, inexplicable, burning failure

For example, I had a terrible race at Gastown Grand Prix in July 2017. I was coming off an amazing (for me) 21st-place finish at the Tour de Delta UCI 1.2 road race, which proved I had the fitness to survive the week of high level racing. However after maybe 3 laps of sprinting out of the hairpin corner and grinding at 50+ km/hr up the cobbled street, I remember telling myself “I can’t hurt this bad for another 60 minutes…” 

I pulled the plug early and limped back to the team tent with my leg burning and throbbing like I had never experienced.

The hairpin corner of Gastown Grand Prix (photo Scott Robarts)

I thought it was a mental failure on my part, and it really got me down for a while. I felt like I had surrendered to the pain, but that everyone was suffering the same as I was. The numbers were hardly different from what I had done in training, so why was it so bloody painful?

My L leg was particularly bad that race, but that’s just how it was: my limitation on the bike has always been about how much pain and burning I can tolerate, and how much extra power my right leg can compensate for.

Gastown2017 LRbalance_INKED
L/R Power Balance chart from Gastown GP 2017 (Strava)

It seems obvious now that something was wrong, but at the time I figured this was just the suffering of our sport, and getting more fit would improve everything.

It didn’t…


Effect on Training Philosophy

This limitation has had ramifications for how I think about training and racing. Sustained efforts are horrible for me, and I’m often unable to complete VO2max or Sweet Spot (SST) efforts that, on paper I should be able to crush easily.

So I found myself leaning toward intermittent protocol that allowed me to maintain elevated HR for longer without pain, and to hit higher power numbers and accumulate greater workload, than when I tried suffering through continuous intervals.

Those of you who read my post on Decreasing-Power 30/15 VO2max intervals, that workout protocol was inspired at least partially from my own failures to sustain continuous VO2max intervals. I was clearly biased toward thinking intermittent intervals worked better than continuous. My UPDATE post (written when I suspected the vascular issue, but before it was confirmed) corrects some of my prior assumptions, and I’m now leaning back toward continuous intervals as more effective for most well-trained athletes.


Racing Conservatively

If there’s one way I’ve benefited from having this condition, it’s that I’ve learned how to race ultra-conservatively in order to delay symptoms onset and actually survive to the end of the race. I’ve always said I’m a smarter racer more than a powerful racer. Turns out, out of necessity!

Once the burning pain begins, there’s really no relief. So I joke with my teammates that I have one match to burn and I gotta use it wisely! My teammates say I look like I’m nose breathing half the time, until all of a sudden I’ll be in full pain-face mode (see the pics above).

I’ve been able to contribute to the team leadout only by hiding and keeping myself safe during races. I can’t contribute to chasing down breaks or working on the front much until the end, because that will put me over the pain threshold which I just can’t recover from.


Why was I so fucked this race? Well, now I know!

So I’ve more or less stopped racing for this season to give the L leg a break. I’ll do the occasional Tuesday Nighter, but mostly just to sit in the pack. I shouldn’t cause my artery to get dramatically worse by continuing to race, but I just want to minimize symptoms. I just don’t want to keep smashing my face into that wall of burning pain, now that I know what it is.

I will race this coming weekend at the BC Provincial Crit Champs in Vancouver, in the brand new Awesome Grand Prix. I’m super excited for it! I only have #onematch to burn, but I’ve been training it up to be one hell of a match!

I’ve basically called my shot: all the local frenemy teams know that if I make it to the finish I’ll be ready to unleash a devastating 30 seconds in the leadout. 

I’ll hopefully have a video of that up next week. Then I’m gonna basically shut down and keep things long, slow, and symptom-free for the rest of the summer.

Until hopefully surgery this winter…

8 thoughts on “Now I Know Why my Left Leg Burns

  1. Damn! Sorry to hear about the diagnosis, but there must be some relief to finally know what was wrong. Thanks again for another post, and hope you are able to enjoy the rest of the season, rest easy, and take of care of this thing.

    Liked by 1 person

  2. Make sure to do tons of research to resolve it and don’t rely on doctors. I had a hip issue for years and after $5,000 in Dr. and PT expenses I fixed it via wearing a special belt I saw browsing the net. Had I not done that I was probably going to have my back fused in a few years. Sometimes surgery is the only option, just make sure and don’t rely on others!

    Liked by 1 person

  3. hey Cory. after a long internet search I think maybe we share the same issue, the thing is that I haven’t diagnosed… yet. after seeing physiotherapist, doctors, running an emg and ultrasound all of them said there’s nothing wrong with my leg, but still I see 45-55% and when I hit over my vo2max after 5 minutes I just want to burn my leg. the following efforts hurts too but maybe 10% below the first one. do you have any suggestions for me to treat this issue ? thanks mate


    1. I think you mean ‘hey Jem’ 😉

      Can’t diagnose anything over the internet of course, but you could bring up the possibility of blood flow limitation or iliac artery endofibrosis to your doctor. The screening & diagnostic stress test process is fairly easy, but the clinician must be familiar with the condition, the techniques, and what they are looking for. A referral to a sports doc or vascular surgeon might be appropriate.

      I can’t recommend specific treatments, but there are some positional changes that you could try. I train in a fully upright position on my home trainer to avoid excessive hip flexion which aggravates the issue. It seems to have helped a bit, but certainly hasn’t solved the issue. I’ve also adapted my racing position to bring me more forward and upright, likewise to limit hip flexion. Definitely not aero anymore! But if it helps get blood flow into my leg, it’s worth the trade off.


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