As the incidence of EAH has increased in recent years, current research has focused on the prevalence of EAH in marathon runners and endurance athletes. One study found 26% of the athletes competing in the Triple Iron ultra-triathlon developed EAH.[19] A similar study measured the prevalence of EAH in open-water ultra-endurance swimmers and found 8% of males and 36% of females developed EAH.[20]