IRON DEFICIENCY DECREASES ENDURANCE WITHOUT ANEMIA
Report #7216
Not having enough iron in your body can tire you during exercise, even if you are not anemic.
Iron deficiency is rare in male athletes, but as many as 30% of female athletes who compete in intercollegiate sports have this condition. If they are tested only for anemia, they wouldn't find out that they are iron deficient. Less than 50% of the iron in your body is in your red blood cells, the rest is in your liver, spleen, bone marrow, lymph nodes, and muscles. You will not develop a low blood count from iron deficiency until you have used up all of your iron reserves. You can have low iron reserves, but not be anemic. During intense exercise, your muscles accumulate a product of metabolism called lactic acid, causing pain, tiredness and poor coordination.
Muscles contain an enzyme called alpha glycero phosphate oxidase, that helps to break down lactic acid. This enzyme contains iron. When your iron reserves are low, alpha glycero phosphate oxidase cannot do its job efficiently and lactic acid accumulates in your muscles and bloodstream and you tire earlier during exercise. All female athletes should be tested for iron deficiency by having blood drawn for a serum ferritin level. If it is low, they need to take iron supplements usually for a year.
By Gabe Mirkin, M.D., for CBS Radio News
YI Zhu, JD Haas. Iron depletion without anemia and physical performance in young women. American Journal of Clinical Nutrition 66: 2(AUG 1997):334-341. 2) Risser Med Sci Spts and Ex. 1988(April);20(2):116-121. 3) Matter: Clinical Science 1987;72:415-422.
Reported 9/1/97; Checked 9/5/05