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By Jeff Rocco, MD

Iron is a critical mineral for performance in endurance athletes.  The abridged story of iron is that it is necessary to create hemoglobin, which is the protein used by red blood cells to deliver oxygen and remove carbon dioxide from and athlete’s exercising muscles.


More hemoglobin = More oxygen delivery.


(This probably explains why many top performing athletes have sought to improve hemoglobin levels, employing techniques outside of the rules of WADA and many sport governing bodies.) Previously we have presented and discussed some of the basics of iron metabolism.  For a review of that material please see Iron and Endurance Performance .  What follows is a discussion of iron deficiency anemia in the endurance athlete. Recently I have personally experienced the diagnosis of iron deficiency, and the benefits that occurred when the deficiency was corrected.  As it turns out, many endurance athletes are iron deficient.  In fact, about 90% of the patients I have evaluated for iron deficiency tested positive.  To make matters worse, it seems that the higher performing athletes are more severely affected.


Symptoms of iron deficiency may be mistaken for over-training syndrome (OTS).  Previously, we have discussed OTS here:  Cortisol and Overtraining  The athlete may simply feel generalized fatigue and find no improvement (or decreasing) performance despite vigilance and attention to recovery, nutrition, and training plans.  Assuming that bleeding such as from a colonic polyp or heavy menstruation have been ruled out, the mechanism for anemia in endurance athletes is not entirely clear.  Foot strike hemolysis can occur in runners when repeated foot falls cause mechanical breakdown of red blood cells.  Recent studies, however, have shown that this effect may be clinically insignificant.(1,2)  Foot strike hemolysis also fails to explain why cyclists exhibit iron deficiency anemia with alarming frequency.  Oxidative stress and inflammation caused by high volume and high intensity exercise have recently been proposed to cause alterations in the red blood cell membrane and subsequent hemolysis.(3,4) The cause of athletic induced anemia may just be the increased levels of oxidative metabolism seen in endurance athletes compared to sedentary individuals.


Iron deficiency anemia is diagnosed with blood tests.  The tests necessary to make the diagnosis include a complete blood count (CBC) with differential, and an iron panel which includes: serum iron, total iron binding capacity (TIBC), iron saturation, and Ferritin.  The range of normal is quite wide, and many times patients, and especially athletes, may be told their levels are normal, when in fact they are low.  Here’s why:  Normal values can vary between laboratories, and normal is a range of values clustered around a mean value for that particular lab.  In other words there are a lot of results that are considered “normal” simply because they occur commonly.  Many of the population tested have some sort of illness that may cause a low hematocrit.  While the results for these patients might be considered normal, they are far from normal for a high performance athlete.


For example consider hematocrit (the volume percentage of blood that is made up of red blood cells).  The normal range for hematocrit is 40-49% for men and 35-46% for women. Doctors are used to treating patients with medical conditions that cause their patients to have hematocrits in the anemic range.  So when a doctor sees a 45 year old age group athlete who lives at 5000’ above sea level with a hematocrit of 39%, that athlete might be told their hematocrit—and therefore their iron level – is within the normal range.  However, if the doctor digs a bit deeper and orders an iron panel, more information is uncovered.  Let’s consider that same athlete with the following lab results:


Test Value Normal
Hemoglobin 13.2 13.3-16.7 g/dL
Hematocrit 39.7 40.0-49.6 %
Iron 68 65-175 mcg/dL
%Saturation 21.7 20-50%
TIBC 314 250-450 mcg/dL
Ferritin 153 5-244 ng/ml



You might look at those results and conclude that this hematocrit is normal and the iron panel is normal too.  But it isn’t.  Not for an otherwise healthy athlete who lives at 5000’ above sea level.  Living and training at altitude should stimulate red blood cell production to the high end of the normal range.  The values for hemoglobin and hematocrit are at the low end of the range.  An Iron level of 68 is much closer to 65 than it is 175.  If this athlete had been female, this same lab might have reported the low end of the range as 37mcg.   Iron levels shouldn’t be lower in women, but they commonly are due to menstruation and child bearing.  A woman’s iron stores can drop by as much as 25% with every child she bears.  In the above example the low % saturation and the normal TIBC tell us that this athlete’s body has the capacity to deal more iron.


Ok, you say this athlete must just need a better diet and some iron supplements.  Come to find out that this athlete has already been on supplements for the past 3 years and is still low on iron.  The point here is that it takes years to improve total body iron stores with oral supplements, and may not even be possible at all.  The body has a difficult time absorbing enough iron to keep up with the depletion caused by high volumes of intense exercise.  Intravenous (IV) therapy is required to make any real, meaningful change.  After IV iron treatment, this particular athlete’s hematocrit increased from 39.7% to 45% in just 6 weeks.  That’s a 13.3% improvement, which translates into 13.3% more oxygen carrying capacity.


To treat iron deficiency anemia I generally recommend a total of 5 IV infusions of iron with one week between each infusion.  The week between infusions gives the body time to process the iron and bind it to proteins.  Too much iron, given too quickly, can be toxic and cause liver damage.  The infusions generally are given slowly over about half an hour.  During the 5 week period of the infusions, it is important for athletes to consume extra protein, up to 1 g per pound of body weight.  The body needs both iron and protein to manufacture the red blood cells.  Athletes can and should continue to train as usual during the infusion period.  Many patients (athletes included) start to feel like they have more energy after only one or two treatments.  Once IV therapy has been completed, additional IV therapy should not be needed for years.  At that point iron levels can be maintained with an oral supplement.  First Endurance MultiV has a good dose of iron (18mg of  elemental iron, chelated) for maintenance purposes.  In my own personal experience, this approach to iron deficiency has helped me to not only to perform better, but to feel better too.




1. Scand J Med Sci Sports. 2012 Jun 5. doi: 10.1111/j.1600-0838.2012.01481.x. [Epub

ahead of print]

Hemolysis induced by an extreme mountain ultra-marathon is not associated with a

decrease in total red blood cell volume.

Robach P, Boisson RC, Vincent L, Lundby C, Moutereau S, Gergelé L, Michel N,

Duthil E, Féasson L, Millet GY.

2. Blood Transfus. 2012 Jul;10(3):377-83. doi: 10.2450/2012.0167-11. Epub 2012 May17.

Foot-strike haemolysis after a 60-km ultramarathon.

Lippi G, Schena F, Salvagno GL, Aloe R, Banfi G, Guidi G

3.  Appl Physiol Nutr Metab. 2008 Dec;33(6):1223-31. doi: 10.1139/H08-125.

Structural alterations of erythrocyte membrane components induced by exhaustive

exercise.  Brzeszczynska J, Pieniazek A, Gwozdzinski L, Gwozdzinski K, Jegier A.

4 . Eur J Appl Physiol. 2008 Jul;103(4):381-91. doi: 10.1007/s00421-008-0726-6.

Athletic induced iron deficiency: new insights into the role of inflammation,

cytokines and hormones.  Peeling P, Dawson B, Goodman C, Landers G, Trinder D.