Athlete’s Anemia – Myth Or Fact

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Athletes’ anemia or sports anemia is well talked about in athletes involved in endurance sports. There are various articles and theories on the internet or similar circles which are leading to unnecessary anxiety as well as needless investigation and treatment. We will try and build a scientific background to understand the subject.

It seems paradoxical that when most of the physiological parameters show improved function, how hemoglobin level should fall with training. However, it has been noticed that endurance-trained athletes have hemoglobin levels about 0.5 g/100ml or lower than that of untrained people. Does this mean they are anemic?


Many studies concluded without much deliberation that endurance sports such as running leads to blood loss. The analysis of the bladder which moves during running showed traces of blood loss. Blood in urine was noticed however the same is not visible to the naked eye as it is in extremely minimal quantities. Foot strike was also considered a reason for blood loss which would increase in heel strike and running on hard surfaces. Hemolysis (rapture or destruction of red blood cells) occurs in plantar vessels causing loss of blood. Blood loss in the gut has also been described in runners. The blood loss is likely to increase by the use of anti-inflammatory and analgesic drugs. However, yet again the loss of blood in a 24-hour cycle is extremely minimum and not visible to the naked eye.

The above-mentioned reasons are related to low Hemoglobin values without further deliberation and this gives rise to the misconception of Sports Anemia. Runners also have a lower level of ferritin (Ferritin is a universal intracellular protein that stores iron and releases it in a controlled fashion). In normal cases ferritin is a good guide to iron stores, it is not reliable in runners. There are many ways to estimate iron stores however, the most reliable is from bone marrow sampling. This test being unpleasant does not resort for obvious reasons.


A detailed study of iron metabolism in middle and long-distance runners showed lower hemoglobin and ferritin levels. However, they all had iron present in their bone marrow stores indicating there was no actual iron deficiency. The medical explanation for the lower level of hemoglobin count and ferritin levels was due to altered red cell catabolism. Opposite to the non-runners, there is less iron in the ferritin compartment and more in the liver/ plasma iron and transferrin compartment. (Transferrin is a blood plasma glycoprotein that plays a vital role in iron metabolism. It is the most critical ferric pool in the body).

Another study further reasoned that endurance athletes have higher plasma volumes which is an acute reaction to strenuous exercise. The statistics show an increase in the plasma volume by 10%, however, red cell mass shows only a slight increase (about 2%). Hence the term ‘anemia’ is inappropriate because in actual red blood mass is increasing. ‘Dilution pseudo-anemia’ is a more accurate term. Hemoglobin and ferritin tests may not take into account the increase in plasma volume, however base test on reduced density thus showing anemia.


The dilution pseudo-anemia of the training state is only of concern if the hemoglobin level is low during the untrained state. The conclusion hence is that pseudo-anemia is not a physiological abnormality but part of an improved physiological state.

Article by: Capt Jitender Harjai Fitness Expert H2FCare

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