Endurance performers and iron-deficiency

By Károly Pikó

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    Károly Pikó MD, is the Chief Physician at the Department of Emergency Medicine, Josa Andras County Hospital, President of the Hungarian Association Medicine and Head Physician of the Hungarian National Olympic and Track and Field Teams.



    Endurance performers are susceptible to iron-deficiency because the absorption of iron cannot balance the losses incurred through training. Therefore, a preventive daily dose of 195mg of ferrous sulphate is necessary, especially for young women. The symptoms of iron-deficiency often remain undiscovered. The haematological parameters of training iron-deficient and anaemic women improve when a daily 210mg ferrous sulphate dose is applied. In endurance performers effects of iron-deficiency on the synthesis of neurotransmitters, cognitive function, mitochondrial function and protein metabolism remain topics for future research studies.


    A large number of sports medicine studies have looked at iron-deficiency anaemia in athletes. Many of them have proved the role of iron in blood synthesis, in the activation of enzymes necessary for synthesis, the catabolism and function of neurotransmitters (dopamine, serotonin and noradrenalin); and in the regeneration of cells. Table 1 summarises the symptoms of iron-deficiency and it is important to emphasise that the symptoms are not due to anaemia.

    Some of the literature argues that performers - especially endurance athletes - are mildly iron-deficient, which places limits on their performance potential. In other research the contrary finding was put forward so the role of iron substitution and preventive iron therapy is often contested.
    The author has examined iron-deficient, iron-deficient anaemic and non-iron deficient endurance athletes and also reviewed the recent related literature and compared it with other findings.

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    Endurance performers from athletics and triathlon were examined. In the morning preprandial blood sample haematological parameters were examined (ferritin, haemoglobin, transferrin, red blood cell volume and iron levels). The participants were divided into three groups:

  1. the first group consisted of male and female athletes, who received no iron preparations.
  2. In the second group participants received 105mg of ferrous sulphate daily.
  3. In the third group known iron-deficient, anaemic female athletes were studied.

    In each group the mathematical average of every parameter was determined. After twelve weeks of training the laboratory studies were repeated.



    Figure 1 summarises the development of laboratory parameters in fifteen male athletes (mean age 18 years), who did not receive iron therapy. In these cases anaemia did not develop, in two cases latently deficient iron levels were noticed. In this group the author observed a tendency towards low iron levels.

    Figure 2 shows the parameters of fifteen female athletes (mean age 20.2 years), who did not receive iron therapy. In six cases iron-deficiency and, in two cases, iron-deficiency anaemia was observed.

    Figure 3 shows the parameters of 20 male competitors (mean age 21.2 years), who received 105mg ferrous sulphate daily during the period of training. After three months neither iron-deficiency, nor iron- deficiency anaemia developed.

    Figure 4 shows the parameters of long distance running and triathlon female athletes who received 105mg daily doses of iron sulphate.


    Figure 5 reviews the haematological parameters of 8 female competitors (mean age 20.5 years), known to have iron-deficiency anaemia, who received 210mg ferrous sulphate daily. Our results show that, in spite of training, the propensity for iron-deficiency and anaemia decreased.


    For decades many studies have looked at the role of iron-deficiency and its effects on performance. Iron absorption and loss should reflect a dynamic equilibrium (Fig. 6.). In the case of sports performers loss of iron is increased by many factors such as perspiration, gastrointestinal and urogenital bleeding during training, and inefficient iron intake. The so-called "runner anaemia" is the result of the increased fragility of the red blood cells, according to some experts. Other studies question that theory by illustrating the similar haematological levels found in swimmers.


    The factors above are especially important in endurance athletes. It is evident that, in the case of iron-deficiency, the organism tries to compensate by increasing the absorption of iron. It is not clear however, whether the organism can maintain the new equilibrium.
    The symptoms of iron-deficiency should be separated from those of anaemia, because they appear long before anaemia is evident and so remain un-recognised. (see Table I.); the symptoms of the patient are often regarded as a result of increased training.
    In spite of the fact that there is controversy over the relationship between iron-deficiency and diminished performance (in mild iron-deficiency no deterioration in performance was noticed), it is difficult to imagine that low iron induced neurotransmitter dysfunction would not negatively influence CNS function or even dysfunction of myogen cell metabolism, both leading to a reduced ability to perform.
    It seems that in the case of endurance sports preventive iron supplementation is necessary, because our organism cannot cope with the increased loss of iron. There is no need to fear an overdose of iron, because only the required amount of iron is absorbed, the rest is eliminated in faeces.



    The studies of iron metabolism in endurance athletes reveal the following:

  1. In endurance athletes iron-deficiency is common and anaemia is often observed.
  2. The haemostatus of these athletes should be monitored at least every three months.
  3. A preventive daily intake of 105mg ferrous sulphate seems to be necessary; over dosage was not observed.
  4. A therapeutic dosage (210mg/day) improved the haemostatic parameters in spite of training. There was no need for intravenous application.
  5. The effect of iron on cognitive functions, neurotransmitter synthesis, protein metabolism and the metabolism within the mitochondria needs future evaluation.


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