The Comrades Marathon: a narrative review of physiological responses and health implications in the world’s oldest ultra-marathon

Introduction The Comrades Marathon is the world’s oldest and largest ultra-marathon, held annually between Durban and Pietermaritzburg, South Africa, since 1921. As a nationally televised event with substantial participation, it provides a unique natural laboratory for studying the physiological demands of prolonged, high-intensity endurance running. This narrative review synthesizes current evidence on physiological responses, performance trends, and health implications associated with participation in the Comrades Marathon . Methods A systematic search of EBSCO, PubMed, SciELO, and Web of Science identified studies published up to December 2025. Of 116 records retrieved, 42 publications (field studies and case reports) met eligibility criteria and focused specifically on the Comrades Marathon . Results Women represented 4.2% of finishers, with female participation beginning in 1975. Growth in finishers during the 1970s was driven primarily by men aged 30–59 years. Men were consistently faster than women across all age groups, although the sex performance gap narrowed over time and overall performance improved. Peak performance occurred at ∼29.9 years in men and ∼36.0 years in women. Medical encounters occurred at rates up to 20 per 1000 starters. The most affected organ systems were fluid/electrolyte (8.8%; 8.3–9.4), central nervous system (4.0%; 3.7–4.5), and gastrointestinal (2.9%; 2.6–3.2). Dehydration (7.5%; 7.0–8.1) and exercise-associated muscle cramping (3.2%; 2.9–3.6) were the most common diagnoses. Exercise-associated hyponatremia was uncommon (