ABSTRACT
Despite its meager contribution to total body composition, iron plays a critical role in optimizing endurance exercise performance: Iron is a) a necessary component of hemoglobin, defining oxygen transport to exercising muscles, b) essential for enzymatic function to provide aerobically based metabolism within the muscle cell, and c) important in establishing psychological attributes necessary for sports competition. Depletion of body stores of iron, either from inadequate dietary intake or excessive losses, is indicated by a fall in serum ferritin level. A level of iron loss sufficient to interfere with hemoglobin synthesis (iron deficiency anemia) impairs athletic performance and clearly needs to be treated with oral iron. Whether milder degrees of iron depletion, in which ferritin levels are low but hemoglobin concentration remains normal, also impairs performance in humans, and whether this nonanemic iron deficiency deserves treatment, is controversial. Findings in studies of animals would say “yes,” but the evidence for impaired performance from nonanemic iron deficiency in humans is far from compelling. The decision of how to view nonanemic iron deficiency in athletes in respect to screening and treatment approaches remains problematic.
