Her respirocytes, which kept her muscles flush with oxygen, even during their most demanding exertions, helped on all of these dimensions. In fact, erythropoietin, a hormone that stimulated red blood cell production, and thus increased oxygen-carrying capacity, was well known for its ability to confer dramatic increases in endurance. This hormone had long been used as a doping drug by athletes, most notably Lance Armstrong, but was only a tiny fraction as effective as Ella’s respirocytes.
