Iron is an essential component of hemoglobin, myoglobin, and several iron-bearing enzymes, all of which affect the delivery of oxygen and the production of energy. Iron deficiency is identified by a three stage scale:
Stage I--Iron depletion. Iron is absent or its stores are decreased. Ferritin levels of between 20 and 50 ng/ml indicate this stage.
Stage II--Iron-deficient erythropoie-sis. Iron is so low that red cell production is diminished. Serum iron levels are low although hemoglobin and hematocrit values would still be within normal range.
Stage III--Iron-deficient anemia. Hemoglobin and hematocrit fall below normal levels. Oxygen delivery to the muscles is reduced and performances decline.
If the amount of iron leaving the body exceeds the iron intake, the body will draw on stored iron to cover the imbalance.
Females are at higher risk for iron deficiency than males. Nearly 70% of females and 40% of males are in Stage I depletion when in hard training.
Iron supplementation should be considered under a physician's guidance. Most therapy is oral, consisting of 36 to 75 mg of Fe three times per day. It is taken prior to eating and often in combination with Vitamin C.
Implications. Iron deficiency is a possible cause of performance decline. When other analyses do not reveal problems and the swimmer is still highly motivated, it may be worthwhile to have iron analyses conducted to determine if a problem exists.
Iron supplementation is a necessary dietary alteration when training at altitude.
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