Ultra-endurance definitely seems to have one of the thinnest sex differentials in sports.

Still, when I ask Google to provide a list of top 10 ultra endurance runners in terms of absolute performance across sexes, it lists not a single woman and elaborates: "While female athletes like Courtney Dauwalter have occasionally won mid-tier ultramarathons outright over the entire field, in highly competitive, top-tier international events, the absolute raw times and physical performance indexes lean heavily toward the elite male field."