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External Iliac Artery Endofibrosis and Leg Pain in Cyclists

Arteriopathy may cause leg pain, weakness and powerlessness

By

Updated September 04, 2013

MRA of the Iliac Arteries

MRA image of the Iliac Arteries

E. Quinn
Most elite athletes are accustomed to experiencing a certain degree of muscle pain and fatigue during high intensity exercise. Recently, however, a subset of athletes (particularly cyclists, rowers and triathletes) have reported symptoms of leg pain and weakness from an unexpected cause - damage to the arteries of the pelvis, groin or lower leg. This damage, or arteriopathy appears to cause the arteries to stretch, narrow or kink in such a way that during high-intensity exercise the athlete experiences decreased blood flow due to the constriction or obstruction of the artery in the affected leg. This lack of blood flow, or ischemia, causes pain, burning, weakness, and powerlessness during exercise. In cyclists this damage most often occurs in the iliac arteries, particularly the external iliac artery.

What Causes Iliac Arteriopathy in Athletes?
The first research on iliac arteriopathy in elite cyclists came out of France in the 1980s and has been growing steadily ever since. Researchers and surgeons speculate that a combination of factors may cause the external iliac arteries to be damaged, including:

  • An extremely high blood flow
  • Repetitive hip flexion
  • An aerodynamic cycling position
Together these factors result in a continuous, repetitive flexing of the artery while under pressure. This stress, over hundreds of hours of high-intensity training, may cause damage to the various layers of the artery wall, or may cause the artery to be stretched, or kinked. Some surgeons have found a tough fibrous tissue build-up on the inside layer of the damaged artery. This fibrous tissue not only narrows the artery, but also prevents it from dilating during exercise. The result is a decreased blood flow to the legs that is often only noticeable during high intensity exercise.

Symptoms of External Iliac Arteriopathy
I took an interest in this condition after I began experiencing symptoms of weakness, pain and powerlessness in my right thigh while cycling at a high intensity. A competitive cyclist for over 20 years, I knew that this wasn't simply muscle fatigue or any sort of soft tissue injury. When I tried to explain the sensations I felt, the only adjective that seemed appropriate was "suffocation." I felt as though the muscles in my leg were suffocating.

Not long after I began researching my symptoms I stumbled upon some obscure research on vascular issues in cyclists, including iliac artery problems showing up in pro cyclists. I eventually took my suspicions and a pile of research abstracts to my doctors and began the process of getting a diagnosis.

During this time, I spoke with several other cyclists across the country who were also diagnosed with external iliac arteriopathy. They all described similar symptoms to mine. They reported feelings of pain, numbness, weakness and a lack of power--typically in the thigh or calf--that went away when they backed off and returned when they went hard. Six of the seven athletes I spoke with experienced symptoms only in one leg. I was fortunate to get diagnosed quickly; many that I spoke with had symptoms for years before finding a doctor familiar with the problem.

Diagnosing External Iliac Arteriopathy with Clinical Tests
Diagnosis is often difficult because most doctors aren't familiar with this condition and wouldn't suspect vascular problems in a fit athlete. Many athletes are misdiagnosed as having compartment syndrome or an overuse, soft tissue injury and are initially referred to physical therapy, which fails to solve the problem.

There are several imaging studies that can help diagnosis a narrowing in the arteries to the legs. An ankle-brachial index (ABI) test before and after exercise is the least invasive test to get an initial diagnosis. This test measures blood pressure at the ankles and in the arm at rest and then after exercise. A normal resting ankle-brachial index is 1 or 1.1 and anything below that is abnormal. Athletes with arteriopathy generally have normal readings at rest, but after exercise (treadmill running or cycling) the ankle pressure in the affected leg drops dramatically, indicating reduced blood flow.

Other tests used to detect the location and degree of the narrowing may include:

  • an exercise duplex ultrasound
  • computed tomography angiography (CTA)
  • magnetic resonance angiography (MRA)
  • extremity arteriography

Page 2: Treating External Iliac Arteriopathy

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