Reduced hemoglobin concentration and red cell hemoglobinization in Italian marathon and ultramarathon runners.

Red blood cell indices, serum iron, and serum ferritin concentration were determined in 45 marathon runners, 56 ultramarathon runners, and 32 healthy sedentary controls. A significant reduction of hemoglobin concentration, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, serum iron, and serum ferritin were found in marathon runners compared to control subjects. The same variables were also reduced, but to a lesser extent, in the less trained ultramarathon runners. The decreased hemoglobin concentration demonstrated in the runners examined is related to both a reduced mean corpuscular hemoglobin concentration and a reduced hematocrit and may depend on a reduction of the body iron stores.