Need to Know: Iliac Artery Endofibrosis

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Chris Hitchcock

If you're spending a lot of time tucked into your tri bike, noticeable fatigue in one leg could be the sign of a (fixable) medical issue.

By Courtney Johnson

Triathlete Mark Cote describes the feeling as "dead leg"—a total lack of power in his left leg while riding, accompanied by a subtle pain and/or burning sensation. At first, he assumed it was "a form thing or a bit of over training." He noticed it on the run, too, especially later into a long run, when the feeling of leg strength imbalance was more pronounced.

He began seeing a chiropractor/bodywork/physio expert. "We worked on it for months, tried to diagnose, and I pretty much halted all of my training and riding to try to get it better," says Cote, who lives in California, where he works as Leader of Marketing and Innovation at Specialized Bikes. "I tried to restart and rebuild like I had in previous years as an athlete. Nothing.”

Cote wasn’t in pain, but he couldn’t push, either. "It was pretty depressing, and I wasn't sure if anything was wrong with me or not," he says. "I wasn't sure we'd figure it out, and frankly I stopped trying to figure it out for a while, hoping it would go away.”

He started doing other activities, primarily kiteboarding, that didn’t initially cause pain or symptom flare-ups. "It wasn't until it really started hurting while I was kiteboarding and surfing that I knew it wasn't going to get better," Cote says. "I started getting pain and symptoms even walking fast up stairs, so I knew I needed to do something. I was passive for too long and had tried the same things over and over. It was the definition of insanity."

In early 2018, Cote’s chiropractor referred him to a run form/PT Specialist named Jeff Moreno. "He really was looking to understand whether I had an imbalance, or a nerve or vascular issue, as the problems are most common in that order," says Cote. "My symptoms were like clockwork—any run on flat ground at 8:30/mile pace or faster would cause my leg to lock up at 0.76 miles. It was that consistent. Any running uphill caused the issue to flare up quicker. On the bike, symptoms were occurring below my FTP, so at around 200 watts my left leg would just shut off."

They ruled out nerve issues or an imbalance and started to look up research papers. A particular article from Dr. Jason Lee, Professor of Vascular Surgery at Stanford University School of Medicine, caught their attention.

"The abstract weirdly referenced everything I was—a male cyclist, between 20 and 40, with reference pain in my non-dominant leg, occurring after 100,000+ km of riding within my lifetime." Cote reached out to Lee and asked if he'd be willing to see him. "We did two key tests that verified the problem," says Cote. "The first was a CT scan with dye to map the vascular structure in my legs. Dr. Lee saw where the left external iliac branches off from the iliac artery; the artery was only 6-7mm in diameter. My right side was over 10mm."

The next test confirmed the diagnosis: Iliac artery endofibrosis, which occurs when the iliac arteries kink, narrow or stretch, causing blood flow to be obstructed and/or constricted.

"The ABI test clearly showed I was a candidate for surgery, while also pointing out where the problem likely was," says Cote. He underwent vascular reconstruction of his left external iliac artery this past June. The day after surgery, Cote walked out of the hospital. He slowly went from walking daily to getting back on the bike.

"My FTP on the bike is higher than ever," he reports. "My run is slowly coming back, but I can run 10-plus miles with no pain. This surgery seriously changed my life. I didn't know if I'd ever ride or run again like before. Now, I'm working on rebuilding to do IRONMAN again."

Dr. Lee, who has operated on 50 athletes with iliac artery endofibrosis since coming to Stanford in 2004, says the condition is underdiagnosed due to it being quite rare. "Most commonly folks describe a loss of power, early fatigue in one leg, unable to climb, or less performance than they're used to," he explains. "It feels like a burning in the thigh and calf. Also most doctors don't assume that someone as healthy and fit as a competitive or recreational cyclist [or triathlete] could have vascular blockages. Most of the time folks think it's some issue from an orthopedic standpoint."

The condition has plagued Aussie professional triathlete Melissa Hauschildt since 2015. "My symptoms would start with the feeling of fatigue in my quad once I hit a certain power, usually around race pace or just below," she explains. "It would feel like a belt around my quad, and as I continued to push on, the belt would tighten and tighten until it felt like the quad was suffocating. I'd continue to push through it, then my quad would cramp up causing this deep burn/ripping sensation. Then the quad would shut down. No matter how strong willed, I'd tell my leg to push and it was like I couldn't control it anymore and I'd be pushing it down with my hand to just turn the pedals."

By October 2016, the two-time IRONMAN 70.3 world champion couldn't finish a race. Hundreds of tests failed to give her any answers. "Doctors initially reported my CT angiogram to be negative," says Hauschildt. "It's very hard to see narrowing of the artery on an angiogram. It's hard to test, and symptoms don't show at rest or even at moderate intensity."

A kink in her common iliac artery was eventually identified and surgery followed, but it wasn't the quick fix that Cote experienced.

"After my operation in March 2017, I still had symptoms so went back under the knife in June, and endofibrosis was also found in the external iliac artery," she says. "It was such a relief to have an answer after years of wondering why my left leg would always shut down in races. I kept blaming myself for not tapering properly or doing something wrong."

Healthy again, Hauschildt is now rebuilding to race at an elite level on the IRONMAN and IRONMAN 70.3 circuits.


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