Arterial endofibrosis is a recently discovered artery disease that is specific to endurance athletes. Cycling is the sport that has shown the greatest number of cases. The endofibrosis is located most frequently in the external iliac artery, but other locations must also be sought. Thigh pain during supramaximal exercise and patient questioning provide strong indications. The diagnosis is confirmed when there is concordance of exercise-induced symptoms, a positive exercise test result and discrete arteriographic characteristics. Treatment is based on folate supplements and standardised surgery carried out by an experienced surgical team.

Approximately one in five top-level cyclists will develop sports-related flow limitations in the iliac arteries. These flow limitations may be caused by a vascular lumen narrowing due to endofibrotic thickening of the intima and/or by kinking of the vessels. In some athletes, extreme vessel length contributes to this kinking. Endofibrotic thickening is a result of a repetitive vessel damage due to haemodynamic and mechanical stress. Atherosclerotic intimal thickening is seldom encountered in these young athletes. This type of sports-related flow limitation shows no relationship with the classical risk factors for atherosclerosis like smoking, hypercholesterolaemia or family predisposition for arterial diseases.

The patient’s history is paramount for diagnosis. If an athlete reports typical claudication-like complaints in a leg at maximal effort, which disappear quickly at rest, approximately two out of three will have a flow limitation in the iliac artery. In current (sports) medical practice, this diagnosis is often missed, since a vascular cause is not expected in this healthy athletic population. Even if suspected, the routinely available diagnostic tests often appear insufficient. Definite diagnosis can be made by a combination of the patient’s history and special designed tests consisting of a maximal cycle ergometer test with ankle blood pressure measurements and/or an echo-Doppler examination with provocative manoeuvres like hip flexion and exercise.

Conservative treatment consists of diminishing or even completely stopping the provocative sports activity. If conservative treatment is insufficient or deemed unacceptable, surgical treatment might be considered. As surgery needs to be tailored to the underlying lesions, a detailed analysis before surgery is necessary. Standard clinical tests, used for visualising atherosclerotic diseases, are inadequate to identify and quantify the causes of flow limitations. Echo-Doppler examination and magnetic resonance angiography with both flexed and extended hips have been proven to be adequate tools. In particular, overprojection and eccentric location of the lesions seriously limit the usefulness of a two-dimensional technique like digital subtraction angiography.

In the early stages, when kinking has not yet led to intimal thickening or excessive lengthening, simple surgical release of the iliac artery is effective. However, for patients with excessive vessel lengths or extensive endofibrotic thickening, a vascular reconstruction may be necessary. A major drawback of these interventions is that long-term effects and complications are unknown.

As both the diagnostic methods and the treatments for this type of flow limitation differ substantially from routine vascular procedures, these patients should be examined in specialised research centres with appropriate diagnostic tools and medical experience.

Objectives: To review the importance, clinical features, investigations, management and prognosis of non-traumatic vascular injuries, affecting the lower limbs of endurance athletes.

Design: Review of literature.

Materials and methods: A literature search was conducted from Medline, Pubmed, the National Electronic Library for Health, Google and Yahoo search engines for related articles and case reports regarding non-traumatic vascular complications involving the lower limb of endurance athletes.

Conclusions: Non-traumatic vascular complications affecting the lower limbs include endofibrosis, stenosis/kinking of iliac arteries, dissection of external iliac artery, adductor canal syndrome, popliteal entrapment syndrome, chronic exertional compartment syndrome and effort-induced venous thrombosis. These are important as they affect athletes at the peak of their career and can be confusing to diagnose. The management is relatively well documented and produces good results in short term but the long term results are not known.

Exercise-induced arterial endofibrosis (EIAE) is now a 20-year-old concept. Initially observed in highly trained cyclists, it has been found in many other male and female endurance athletes. Most stenoses are located on the first centimetres of the external iliac artery but other localisation may be found. The disease is defined by specific histological findings showing fibrosis of the intimal and medial wall of the artery. Ankle pressure measurement plays a key role in the diagnosis of EIAE provided that the exercise tests reproduce symptoms and are performed with the subject being highly trained, and that pressure measurements are performed early following exercise. Various cut-off values have been proposed in the literature. Magnetic resonance imaging or arteriography or ultrasound imaging should be performed by trained operators only. Surgical 'endofibrosectomy' is preferable in young cyclists generally associated with a saphenous enlargement patch. We do not recommend angioplasty. Athletes are generally allowed to return to competition within 3-4 months following surgery. Many unanswered questions remain, specifically about the pathophysiology of this disease. Mechanical and pressure strain play a central role in the development of EIEA, but nutritional and haemorrheological factors, hormonal changes and a genetic predisposition are likely to contribute. New techniques could facilitate the diagnosis of EIAE.