Sports anemia, iron supplements, and blood doping.

1) Athletes tend to have lower hemoglobin concentrations than sedentary counterparts. This has been called sports anemia, a misnomer. 2) Sports anemia is a false anemia and a beneficial adaptation to aerobic exercise, caused by an expanded plasma volume that dilutes red blood cells. 3) Athletes, however, can also develop true anemia, most commonly caused by iron deficiency. True anemia curbs athletic performance, but nonanemic iron deficiency does not. 4) Iron supplements are useful for women endurance athletes who repeatedly develop iron deficiency anemia despite dietary advice. 5) Some endurance athletes today are blood doping by abusing recombinant human erythropoietin (rEPO). They risk dying to win.