“…In two of the toughest ultra-marathons in the world, women accounted on average for ~21.5% in 'Badwater' and ~10.8% in 'Spartathlon' [5]. In most ultra-marathons, the number of female finishers increased across years [5,6]. For example, in the 'Swiss Alpine Marathon' in Switzerland, women's participation increased from ~10% in 1998 to ~16% in 2011 [6].…”