Ultra-endurance running is increasingly seeing women match or outperform men, prompting scientists to examine whether female athletes have physiological or psychological advantages over very long distances. While men hold a clear 10-12% performance edge in races up to marathon length, that gap narrows sharply the further athletes run, with some researchers suggesting women could even have the potential to be faster beyond ultra-marathon distances. Recent results, including Jasmin Paris becoming the first woman to finish the notoriously brutal Barkley Marathons and Rachel Entrekin winning the Cocodona 250 outright, have fuelled the debate.

A study of over 20 years of amateur ultra-race data by RunRepeat and the International Association of Ultrarunners found the "gender pace gap" shrinks to just 0.25% in 100-mile races. Experts such as Professor Andy Jones of the University of Exeter point to possible explanations including more efficient fat metabolism, oxygen-efficient "slow twitch" muscle fibres and greater fatigue resistance in women, though he and Dr Richard Burden of the UK Sports Institute stress the science remains under-researched compared with shorter distances. Runner Sophie Woods, who recently broke the Via Alpina record by six days, argues mental strength and preparation, rather than raw speed, are what set women apart in these gruelling events.