Iliac artery endofibrosis #2a - diagnosis part 1

For the DIY enthousiasts: self-diagnosis

In my last post, I described the symptoms I experienced as a result of endofibrosis. Once you notice clear symptoms, the logical next step is to investigate their cause and get a proper diagnosis. However, there’s no need to rush to the hospital immediately, since many far less serious factors can produce similar complaints – things like a pinched nerve, a tilted pelvis, or even poor bike fit. After ruling out these more “harmless” causes, you can start to consider the possibility of iliac artery endofibrosis and consult an expert if needed. To help clarify your doubts, you can also perform a targeted self-test, which is exactly what I did.

One kink to destroy it all

The nature of iliac artery endofibrosis – let’s go with EIAE from now on – in athletes makes it difficult to detect. At rest, everything appears normal, but during efforts, symptoms emerge. The artery supplying blood to the leg becomes narrowed and cannot meet the increased demand for blood flow.

When in tucked cycling position, which reduces the hip angle, symptoms often worsen. This smaller hip angle creates a kink in the artery, further restricting blood flow. In fact, it is this repeated kinking that initiates the development of endofibrosis, as the constant compression and stretching damage the artery’s inner lining. Over time, scar tissue forms, progressively narrowing the artery even more. Because this process repeats with every pedal stroke, EIAE tends to worsen if you continue cycling without intervention.

Self-diagnosis – DIY blood pressure testing

When there’s a narrowing in the artery, less blood can get through. During exercise, your muscles need a lot more blood. But because the artery is partly blocked, it can’t deliver enough, so the pressure past the narrowed area drops. Think of it like squeezing a garden hose: water pressure goes down on the other side of the pinch. And exactly this pressure drop you can measure yourself pretty easily! And that is exactly what I did. All you need is a blood pressure monitor with a small cuff that fits your ankle.

It’s important to take these measurements after intense effort, since that’s when your blood demand is highest – and when any pressure drop will become most obvious. Here’s how I did it:

1. Ride 6min at 95% of FTP.

2. Get off the bike asap, lay down flat on your back (e.g. all limbs are on the same level as your heart)

3. Measure BP at the arm.

4. Measure BP at the leg.

You’ll want to perform all these steps as quickly as possible. After exercise, blood pressure levels can normalize within just a few minutes, so if you wait too long, you might miss the pressure drop entirely or end up with a false positive. Ideally, you would use two blood pressure monitors to measure your arm and leg pressures simultaneously (I didn’t).

It’s also best to test both legs, so you can compare the results side by side. Once you’ve collected your measurements, you can calculate the Ankle-Brachial Index (ABI) for each test to help interpret your results. If you’re interested in more in-depth information about how EIAE affects blood pressure, I recommend read this study and this study.

\( \text{ABI} = \frac{\text{Systolic pressure at ankle (leg)}}{\text{Systolic pressure at arm}} \)

I performed four measurements myself, which you can see in the table below. Ideally, I would have measured even faster, since blood pressure levels start returning to normal within moments after stopping exercise. By the time I measured my leg, the values were probably already partially recovered. Still, the consistently low ABI in my left leg, along with the clear difference between my left and right leg results, convinced me to seek expert help for EIAE.

Obligatory disclaimer

Of course, doing this kind of self-test is no substitute for a professional medical diagnosis. But it can help ease your mind or give you that extra push to take action when it’s needed.

In my next post, I’ll cover the second part of the diagnostic process: the tests you’ll undergo at the hospital and why it’s so important to find a hospital or clinic that specializes in this type of injury in athletes. I hope this deeper dive was helpful! Feel free to subscribe and follow along on this topic!