Iliac Artery Endofibrosis in Endurance Cyclists: An Underrecognized Cause of Exercise-Induced Leg Pain - a narrative review

Background. Iliac artery endofibrosis (IAE) is a rare, non-atherosclerotic vasculopathy causing exercise-induced flow limitation in the external iliac artery of endurance athletes, predominantly cyclists. Because it mimics musculoskeletal, neurological, and orthopaedic causes of exertional leg pain, diagnosis is often delayed by years.Aim. To synthesise the pathophysiology, diagnostic pathway, treatment options, and safety outcomes of IAE, alongside related non-atherosclerotic and sport-related peripheral vascular conditions entering its differential diagnosis.Materials and Methods. Narrative review of peer-reviewed English-language case reports, case series, cohort studies, scoping reviews, consensus statements, and methodological studies addressing iliac artery flow limitation, endofibrosis, kinking, and related vascular compression syndromes in athletes, supplemented by broader peripheral arterial disease literature relevant to diagnostic technique validation.Results. IAE most often affects the left external iliac artery of male competitive cyclists after high cumulative training volumes, arising from hip-flexion-related arterial kinking, psoas hypertrophy, and intrinsic intimal fibrosis histologically distinct from atherosclerosis. Diagnosis relies on exercise-provoked ankle-brachial index measurement, duplex ultrasonography, and cross-sectional angiography, with emerging adjuncts including near-infrared spectroscopy and functional magnetic resonance angiography.Conclusions. IAE should be considered in any endurance athlete with reproducible, effort-dependent, rapidly resolving unilateral leg symptoms once musculoskeletal causes are excluded. Surgical revascularisation remains the definitive treatment; endovascular therapy alone is discouraged. Standardised diagnostic criteria and prospective outcome registries are still lacking.