Thursday, March 26, 2009
Endurance Athletes - Anemia and iron deficiency
Anemia has been identified as the most common medical condition among athletes. It is more common in females than males and especially in female athletes.
Anemia and iron deficiency
The capacity of the body to transport oxygen is one of the factors which limits physical performance. Oxygen is transported in the blood by the pigment of the red blood cells (haemoglobin). If the concentration of haemoglobin is reduced, the oxygen-transporting capacity of the body is impaired, and therefore the capacity to perform drops.
Anemia is said to occur when the concentration of haemoglobin falls below that specified as normal for the individual's age and sex. Athletes who subject themselves to prolonged, strenuous exertion (for example, by daily endurance training) may develop a degree of anemia.
Iron deficiency is the most common form of true anemia among athletes. Stores of iron are depleted before clinical signs show. Iron occurs in small quantities in the body, totaling about 1.5-1.75 oz (4-5g) in the adult. It is required not only for the manufacture of haemoglobin, but also for that of the related compound, myoglobin, found in muscle tissue. Both these substances bind oxygen and play an important role in its transport. Iron is mainly stored in haemoglobin(64%) and bone marrow(27%). Iron deficiency anemia is most prevalent among menstruating women and males between the age of 11 and 14.
Three conditions occur during anemia: erythrocytes (red blood cells) are too small, haemoglobin is decreased, and ferritin concentration is low. Ferritin is an iron-phosphorous-protein complex that normally contains 23% iron. There are many ways that athletes can be iron deficient. Gastrointestinal (GI) losses are common in runners because of bowel ischemia. Aspirin or non-steroidal anti-inflammatory drugs (NSAIDS) may cause cause GI blood loss. Runners absorb 16% of iron from the GI tract as compared with 30% in non-athletes who are iron deficient. Menstrual losses account for most iron loss in female athletes. Average menstrual iron loss is 0.6 to 1.5 mg per day. Inadequate dietary intake of iron is the primary cause of iron deficiency. The recommended daily allowance (RDA) is 15 mg per day for females and 10 mg per day for males. The average diet contains 5 to 7 mg or iron per 100 kcal. Because female athletes often eat less than they need, they also fail to consume enough iron. If the athlete is a vegetarian they may run the risk of lacking in iron.
Anemia can be confirmed by measuring the hemoglobin levels of the body. An iron deficiency can be identified by blood cell analysis and by determining the serum ferritin level and , if necessary, the amount of haemoisderin in the bone marrow. Young people store only small amounts of iron, and low serum ferritin levels are therefore normal in individuals under the age twenty. The examining doctor needs expert knowledge in order to be able to decide whether or not an apparent iron deficiency is really significant. On the whole, it is not most common for adults on a well-balanced diet to suffer from iron deficiency.